| 1. |
- Adriani, O., et al.
(författare)
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Design of an Antimatter Large Acceptance Detector In Orbit (ALADInO)
- 2022
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Ingår i: Instruments. - : MDPI AG. - 2410-390X. ; 6:2
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Tidskriftsartikel (refereegranskat)abstract
- A new generation magnetic spectrometer in space will open the opportunity to inves-tigate the frontiers in direct high-energy cosmic ray measurements and to precisely measure the amount of the rare antimatter component in cosmic rays beyond the reach of current missions. We propose the concept for an Antimatter Large Acceptance Detector In Orbit (ALADInO), designed to take over the legacy of direct measurements of cosmic rays in space performed by PAMELA and AMS-02. ALADInO features technological solutions conceived to overcome the current limi-tations of magnetic spectrometers in space with a layout that provides an acceptance larger than 10 m2 sr. A superconducting magnet coupled to precision tracking and time-of-flight systems can provide the required matter–antimatter separation capabilities and rigidity measurement resolution with a Maximum Detectable Rigidity better than 20 TV. The inner 3D-imaging deep calorimeter, designed to maximize the isotropic acceptance of particles, allows for the measurement of cosmic rays up to PeV energies with accurate energy resolution to precisely measure features in the cosmic ray spectra. The operations of ALADInO in the Sun–Earth L2 Lagrangian point for at least 5 years would enable unique revolutionary observations with groundbreaking discovery poten-tials in the field of astroparticle physics by precision measurements of electrons, positrons, and antiprotons up to 10 TeV and of nuclear cosmic rays up to PeV energies, and by the possible unam-biguous detection and measurement of low-energy antideuteron and antihelium components in cosmic rays.
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| 2. |
- Ahlkvist, Linda, et al.
(författare)
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Evidence for neural contribution to islet effects of DPP-4 inhibition in mice
- 2016
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Ingår i: European Journal of Pharmacology. - : Elsevier BV. - 1879-0712 .- 0014-2999. ; 780, s. 46-52
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Tidskriftsartikel (refereegranskat)abstract
- It has been suggested that neural mechanisms may contribute to effects of the incretin hormones, and, therefore, also to the effects of dipeptidyl peptidase (DPP-4) inhibition. We therefore examined whether muscarinic mechanisms are involved in the stimulation of insulin secretion by DPP-4 inhibition. Fasted, anesthetized mice were given intraperitoneal saline or the muscarinic antagonist atropine (5mg/kg) before duodenal glucose (75mg/mouse), with or without the DPP-4 inhibitor NVPDPP728 (0.095mg/mouse), or before intravenous glucose (0.35g/kg) with or without co-administration with GLP-1 or glucose-dependent insulinotropic polypeptide (GIP) (both 3nmol/kg). Furthermore, isolated islets were incubated (1h) in 2.8 and 11.1mM glucose, with or without GIP or GLP-1 (both 100nM), in the presence or absence of atropine (100µM). Duodenal glucose increased circulating insulin and this effect was potentiated by DPP-4 inhibition. The increase in insulin achieved by DPP-4 inhibition was reduced by atropine by approximately 35%. Duodenal glucose also elicited an increase in circulating intact GLP-1 and GIP and this was augmented by DPP-4 inhibition, but these effects were not affected by atropine. Atropine did also not affect the augmentation by GLP-1 and GIP on glucose-stimulated insulin secretion from isolated islets. Based on these findings, we suggest that muscarinic mechanisms contribute to the stimulation of insulin secretion by DPP-4 inhibition through neural effects induced by GLP-1 and GIP whereas neural effects do not affect the levels of GLP-1 or GIP or the islet effects of the two incretin hormones.
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| 3. |
- Ahrén, Bo, et al.
(författare)
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Glucose effectiveness : Lessons from studies on insulin-independent glucose clearance in mice
- 2021
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Ingår i: Journal of Diabetes Investigation. - : Wiley. - 2040-1116 .- 2040-1124. ; 12:5, s. 675-685
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Forskningsöversikt (refereegranskat)abstract
- Besides insulin-mediated transport of glucose into the cells, an important role is also played by the non-insulin-mediated transport. This latter process is called glucose effectiveness (acronym SG), which is estimated by modeling of glucose and insulin data after an intravenous glucose administration, and accounts for ≈70% of glucose disposal. This review summarizes studies on SG, mainly in humans and rodents with focus on results achieved in model experiments in mice. In humans, SG is reduced in type 2 diabetes, in obesity, in liver cirrhosis and in some elderly populations. In model experiments in mice, SG is independent from glucose levels, but increases when insulin secretion is stimulated, such as after administration of the incretin hormones, glucagon-like peptide-1 and glucose-dependent insulinotropic polypeptide. SG is reduced in insulin resistance induced by high-fat feeding and by exogenous administration of glucagon. Glucose-dependent (insulin-independent) glucose disposal is therefore important for glucose elimination, and it is also well regulated. It might be of pathophysiological relevance for the development of type 2 diabetes, in particular during insulin resistance, and might also be a target for glucose-reducing therapy. Measuring SG is essentially important when carrying out metabolic studies to understand glucose homeostasis.
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| 4. |
- Ahrén, Bo, et al.
(författare)
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Importance of quantifying insulin secretion in relation to insulin sensitivity to accurately assess beta cell function in clinical studies.
- 2004
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Ingår i: European Journal of Endocrinology. - : Oxford University Press (OUP). - 1479-683X .- 0804-4643. ; 150:2, s. 97-104
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Forskningsöversikt (refereegranskat)abstract
- Insulin sensitivity and insulin secretion are mutually related such that insulin resistance is compensated by increased insulin secretion. A correct judgement of insulin secretion therefore requires validation in relation to the insulin sensitivity in the same subject. Mathematical analyses of the relationship between insulin sensitivity and insulin secretion has revealed a hyperbolic function, such that the product of the two variables is constant. This product is usually called the disposition index. Several techniques may be used for its estimation such as data derived from the frequently sampled i.v. glucose tolerance test, the oral glucose tolerance test or the glucose-dependent arginine stimulation test or the euglycemic hyperinsulinemic clamp technique in combination with a test on insulin secretion. Using these techniques the compensatory increase in beta cell function in insulin resistance has been verified in obesity, in pregnancy and after glucocorticoid administration as has the defective beta cell function as the underlying cause of impaired glucose tolerance and type 2 diabetes. Similarly, combined analysis of insulin sensitivity and insulin secretion has shown a down-regulation of beta cell function in increased insulin sensitivity accompanying weight reduction in obesity and following exercise. Acknowledging this inverse relationship between insulin secretion and insulin sensitivity therefore requires estimation of both variables for correct assessment in any individual.
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| 5. |
- Ahrén, Bo, et al.
(författare)
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Improved meal-related beta-cell function and insulin sensitivity by the dipeptidyl peptidase-IV inhibitor vildagliptin in metformin-treated patients with type 2 diabetes over 1 year.
- 2005
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Ingår i: Diabetes Care. - : American Diabetes Association. - 1935-5548 .- 0149-5992. ; 28:8, s. 1936-1940
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Tidskriftsartikel (refereegranskat)abstract
- OBJECTIVE—To examine the effects of dipeptidyl peptidase-IV (DPP-4) inhibition on meal-related β-cell function and insulin sensitivity over 52 weeks in type 2 diabetes. RESEARCH DESIGN AND METHODS—In a 12-week core study, placebo (n = 51) or vildagliptin (n = 56; 50 mg OD) was added to metformin treatment (1.5–3.0 mg/day). A 40-week extension followed in 71 patients. Meal tests were performed at 0, 12, 24, and 52 weeks; glucose, insulin, and C-peptide were evaluated. RESULTS—In subjects completing 52 weeks with participation in all meal tests (n = 57), HbA1c (A1C) decreased in the vildagliptin/metformin group (VM group, n = 31) but increased in the placebo/metformin group (PM group, n = 26; between-group difference −1.0 ± 0.2%; P < 0.001; baseline of all subjects combined 7.7 ± 0.1%). Also, fasting glucose decreased in the VM group but increased in the PM group (difference −0.9 ± 0.3 mmol/l, P = 0.016; baseline 9.8 ± 0.3 mmol/l). Insulin secretion (postmeal suprabasal area under the 0- to 30-min C-peptide curve divided by the 30-min increase in glucose) was increased in the VM group but was reduced in the PM group (difference +0.011 ± 0.03 pmol/l 30 min/mmol/l, P = 0.018; baseline 0.036 ± 0.02). Insulin sensitivity during meal ingestion (oral glucose insulin sensitivity) increased in the VM group but was not altered in the PM group (difference +27 ± 4 ml · min−1 · m−2, P = 0.036; baseline 246 ± 6). Insulin secretion related to insulin sensitivity (adaptation index) increased in the VM group but decreased in the PM group (difference +3.2 ± 1.0, P = 0.040; baseline 9.1 ± 0.5). The change in adaptation index correlated to the change in A1C (r = −0.39, P = 0.004). CONCLUSIONS—This study presents evidence that DPP-4 inhibition by vildagliptin when added to metformin in type 2 diabetes over 52 weeks improves β-cell function along with improved postmeal insulin sensitivity.
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| 6. |
- Ahrén, Bo, et al.
(författare)
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The augmenting effect on insulin secretion by oral versus intravenous glucose is exaggerated by high-fat diet in mice.
- 2008
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Ingår i: Journal of Endocrinology. - 1479-6805. ; 197:1, s. 181-187
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Tidskriftsartikel (refereegranskat)abstract
- To study whether the incretin effect is involved in adaptively increased insulin secretion in insulin resistance, glucose was infused at a variable rate to match glucose levels after oral glucose (25 mg) in normal anesthetized C57BL/6J female mice or in mice rendered insulin resistant by 8 weeks of high-fat feeding. Insulin response was markedly higher after oral than i.v. glucose in both groups, and this augmentation was even higher in high-fat fed than normal mice. In normal mice, the area under the curve (AUC(insulin)) was augmented from 4.0+/-0.8 to 8.0+/-1.8 nmol/lx60 min by the oral glucose, i.e. by a factor of 2 (P=0.023), whereas in the high-fat fed mice, AUC(insulin) was augmented from 0.70+/-0.4 to 12.4+/-2.5 nmol/lx60 min, i.e. by a factor of 17 (P<0.001). To examine whether the incretin hormone glucagon-like peptide-1 (GLP-1) is responsible for this difference, the effect of i.v. GLP-1 was compared in normal and high-fat fed mice. The sensitivity to i.v. GLP-1 in stimulating insulin secretion was increased in the high-fat diet fed mice: the lowest effective dose of GLP-1 was 650 pmol/kg in normal mice and 13 pmol/kg in the high-fat diet fed mice. We conclude that 1) the incretin effect contributes by approximately 50% to insulin secretion by the oral glucose in normal mice, 2) this effect is markedly exaggerated in insulin-resistant mice fed a high-fat diet, and 3) this augmented incretin contribution in the high-fat fed mice may partially be explained by GLP-1.
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| 7. |
- Alsalim, Wathik, et al.
(författare)
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Effect of single-dose DPP-4 inhibitor sitagliptin on β-cell function and incretin hormone secretion after meal ingestion in healthy volunteers and drug-naïve, well-controlled type 2 diabetes subjects
- 2018
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Ingår i: Diabetes, Obesity and Metabolism. - : Wiley. - 1462-8902. ; 20:4, s. 1080-1085
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Tidskriftsartikel (refereegranskat)abstract
- To explore the effects of a single dose of the DPP-4 inhibitor sitagliptin on glucose-standardized insulin secretion and β-cell glucose sensitivity after meal ingestion, 12 healthy and 12 drug-naïve, well-controlled type 2 diabetes (T2D) subjects (mean HbA1c 43mmol/mol, 6.2%) received sitagliptin (100mg) or placebo before a meal (525kcal). β-cell function was measured as the insulin secretory rate at a standardized glucose concentration and the β-cell glucose sensitivity (the slope between glucose and insulin secretory rate). Incretin levels were also monitored. Sitagliptin increased standardized insulin secretion, in both healthy and T2D subjects, compared to placebo, but without increasing β-cell glucose sensitivity. Sitagliptin also increased active glucose-dependent insulinotropic polypeptide (GIP) and glucagon-like peptide-1 (GLP-1) and reduced total (reflecting the secretion) GIP, but not total GLP-1 levels. We conclude that a single dose of DPP-4 inhibition induces dissociated effects on different aspects of β-cell function and incretin hormones after meal ingestion in both healthy and well-controlled T2D subjects.
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| 8. |
- Alsalim, Wathik, et al.
(författare)
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Incretin and islet hormone responses to meals of increasing size in healthy subjects.
- 2015
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Ingår i: Journal of Clinical Endocrinology and Metabolism. - : The Endocrine Society. - 1945-7197 .- 0021-972X. ; 100:2, s. 561-568
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Tidskriftsartikel (refereegranskat)abstract
- Context: Postprandial glucose homeostasis is regulated through the secretion of glucagon-like peptide 1 (GLP-1) through stimulation of insulin secretion and inhibition of glucagon secretion. However, how these processes dynamically adapt to demands created by caloric challenges achieved during daily life is not known. Objective: To explore adaptation of incretin and islet hormones after mixed meals of increasing size in healthy subjects. Design: Twenty-four healthy lean subjects ingested a standard breakfast after an overnight fast followed, after four hours, by a lunch of different size (511, 743 and 1034 kcal) but with identical nutrient composition together with 1.5g paracetamol. Glucose, insulin, C-peptide, glucagon, intact glucagon-like peptide-1 (GLP-1) and glucose-dependent insulinotropic polypeptide (GIP) and paracetamol were measured after the meals. Main outcome measure: Area under the 180 min curve (AUC) for insulin, C-peptide, glucagon, GLP-1 and GIP and model- derived ß-cell function and paracetamol appearance. Results: Glucose profiles were similar after the two larger meals whereas after the smaller meal, there was a post-peak reduction below baseline to nadir of 3.8±0.1mmol/l after 75min (p<0.001). AUC for GLP-1, GIP, insulin and C-peptide were significantly higher by increasing the caloric load as was β-cells sensitivity to glucose. In contrast, AUC glucagon was the same for all three meals, although there was an increase in glucagon after the postpeak glucose reduction in the smaller meal. The 0-20 min paracetamol appearance was increased by increasing meal size. Conclusion: Mixed lunch meals of increasing size elicit a caloric dependent insulin response due to increased β-cell secretion achieved by increased GIP and GLP-1 levels. The adaptation at larger meals results in identical glucose excursions, whereas after a lower caloric lunch the insulin response is high resulting in postpeak suppression of glucose below baseline.
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| 9. |
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| 10. |
- Alsalim, Wathik, et al.
(författare)
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Persistent whole day meal effects of three dipeptidyl peptidase-4 inhibitors on glycaemia and hormonal responses in metformin-treated type 2 diabetes
- 2020
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Ingår i: Diabetes, Obesity and Metabolism. - : Wiley. - 1462-8902 .- 1463-1326. ; 22:4, s. 590-598
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Tidskriftsartikel (refereegranskat)abstract
- Aim: Dipeptidyl peptidase-4 (DPP-4) inhibition has effects on both fasting and postprandial glucose. However, the extent of this effect over the whole day and whether different DPP-4 inhibitors have the same effects have not been established. We therefore explored the whole day effects of three different DPP-4 inhibitors versus placebo on glucose, islet and incretin hormones after ingestion of breakfast, lunch and dinner in subjects with metformin-treated and well-controlled type 2 diabetes. Methods: The study was single-centre and crossover designed, involving 24 subjects [12 men, 12 women, mean age 63 years, body mass index 31.0 kg/m2, glycated haemoglobin 44.7 mmol/mol (6.2%)], who underwent four test days in random order. Each whole day test included ingestion of standardized breakfast (525 kcal), lunch (780 kcal) and dinner (560 kcal) after intake of sitagliptin (100 mg) or vildagliptin (50 mg twice), or saxagliptin (5 mg) or placebo. Results: Compared with placebo, DPP-4 inhibition reduced glucose levels, increased beta-cell function (insulin secretory rate in relation to glucose), suppressed glucagon, increased intact glucagon-like-peptide-1 (GLP-1) and glucose-dependent insulinotropic polypeptide (GIP) but suppressed total GLP-1 and GIP after all three meals. The effects were sustained throughout the daytime period with similar changes after each meal and did not differ between the DPP-4 inhibitors. Conclusions: DPP-4 inhibition has persistent daytime effects on glucose, islet and incretin hormones with no difference between three different DPP-4 inhibitors.
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| 11. |
- Chan, Hui Min, et al.
(författare)
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Effects of increasing doses of glucagon-like peptide-1 on insulin-releasing phases during intravenous glucose administration in mice
- 2011
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Ingår i: American Journal of Physiology: Regulatory, Integrative and Comparative Physiology. - : American Physiological Society. - 0363-6119 .- 1522-1490. ; 300:5, s. 1126-1133
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Tidskriftsartikel (refereegranskat)abstract
- Chan HM, Jain R, Ahren B, Pacini G, D'Argenio DZ. Effects of increasing doses of glucagon-like peptide-1 on insulin-releasing phases during intravenous glucose administration in mice. Am J Physiol Regul Integr Comp Physiol 300: R1126-R1133, 2011. First published February 9, 2010; doi:10.1152/ajpregu.00687.2010.-The increase in insulin secretion caused by glucagon-like peptide-1 (GLP-1) and GLP-1 mimetics observed during an intravenous glucose test (IVGTT) has been reported in both normal and disease animal models, as well as in humans. In this study, a hierarchical population modeling approach is used, together with a previously reported model relating glucose to insulin appearance, to determine quantitative in vivo dose-response relationships between GLP-1 dose level and both first-and second-phase insulin release. Parameters of the insulin kinetic model were estimated from the complete set of glucose and insulin data collected in 219 anesthetized nonfasted NMR-imaged mice after intravenous injection of glucose (1 g/kg) alone or with GLP-1 (0.03-100 nmol/kg). The resulting dose-response curves indicate a difference in GLP-1 effect on the two release phases, as is also evident from the different ED50 parameter values (0.107 vs. 6.65 nmol/kg for phase 1 vs. phase 2 insulin release parameters). The first phase of insulin release is gradually augmented with increasing GLP-1 dose, reaching saturation at a dose of similar to 1 nmol/kg, while the second-phase release changes more abruptly at GLP-1 doses between 3 and 10 nmol/kg and shows a more pronounced 100-fold increase between control and the high GLP-1 dose of 100 nmol/kg Moreover, separate disposition indices calculated for phase 1 and 2 insulin release, show a different pattern of increase with increasing GLP-1 dose.
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| 12. |
- Færch, Kristine, et al.
(författare)
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Insulin resistance is accompanied by increased fasting glucagon and delayed glucagon suppression in individuals with normal and impaired glucose regulation
- 2016
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Ingår i: Diabetes. - : American Diabetes Association. - 0012-1797 .- 1939-327X. ; 65:11, s. 3473-3481
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Tidskriftsartikel (refereegranskat)abstract
- Hyperinsulinemia is an adaptive mechanism that enables the maintenance of normoglycemia in the presence of insulin resistance. We assessed whether glucagon is also involved in the adaptation to insulin resistance. A total of 1,437 individuals underwent an oral glucose tolerance test with measurements of circulating glucose, insulin, and glucagon concentrations at 0, 30 and 120 min. Early glucagon suppression was defined as suppression in the period from 0 to 30 min, and late glucagon suppression as 30 to 120 min after glucose intake. Insulin sensitivity was estimated by the validated insulin sensitivity index. Individuals with screen-detected diabetes had 30% higher fasting glucagon levels and diminished early glucagon suppression, but greater late glucagon suppression when compared with individuals with normal glucose tolerance (P 0.014). Higher insulin resistance was associated with higher fasting glucagon levels, less early glucagon suppression, and greater late glucagon suppression (P < 0.001). The relationship between insulin sensitivity and fasting glucagon concentrations was nonlinear (P < 0.001). In conclusion, increased fasting glucagon levels and delayed glucagon suppression, together with increased circulating insulin levels, develop in parallel with insulin resistance. Therefore, glucose maintenance during insulin resistance may depend not only on hyperinsulinemia but also on the ability to suppress glucagon early after glucose intake.
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| 13. |
- Frid, Anders, et al.
(författare)
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Effect of oral pre-meal administration of betaglucans on glycaemic control and variability in subjects with type 1 diabetes
- 2017
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Ingår i: Nutrients. - : MDPI AG. - 2072-6643. ; 9:9
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Tidskriftsartikel (refereegranskat)abstract
- We conducted a double-blind placebo-controlled crossover pilot study to investigate the effect of oat betaglucans (β-glucan) on glycaemic control and variability in adults with type 1 diabetes (T1D; n = 14). Stomacol® tablets (1.53 g of β-glucan) or placebo (Plac) were administered three times daily before meals for two weeks. Glucose levels were monitored during the second week by continuous glucose monitoring (CGM). There was an increase in basic measures of glycaemic control (maximal glucose value 341 ± 15 vs. 378 ± 13 mg/dL for Plac and β-glucan, p = 0.004), and average daily risk range (62 ± 5 vs. 79 ± 4 mg/dL for Plac and β-glucan, p = 0.003) favouring Plac over β-glucan, but no increase in the M-value (the weighted average of the glucose values) or other more complex measures. Basic measures of glucose variability were also slightly increased during β-glucan treatment, with no difference in more complex measures. However, glycaemic variability increased between the first and last two CGM days on Plac, but remained unchanged on β-glucan. In conclusion, in this pilot study we were unable to demonstrate a general positive effect of β-glucan before meals on glucose control or variability in T1D.
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| 14. |
- Jönsson, Tommy, et al.
(författare)
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A Paleolithic diet confers higher insulin sensitivity, lower C-reactive protein and lower blood pressure than a cereal-based diet in domestic pigs.
- 2006
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Ingår i: Nutrition & Metabolism. - : Springer Science and Business Media LLC. - 1743-7075. ; 3:Article nr. 39
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Tidskriftsartikel (refereegranskat)abstract
- A Paleolithic diet has been suggested to be more in concordance with human evolutionary legacy than a cereal based diet. This might explain the lower incidence among hunter-gatherers of diseases of affluence such as type 2 diabetes, obesity and cardiovascular disease. The aim of this study was to experimentally study the long-term effect of a Paleolithic diet on risk factors for these diseases in domestic pigs. We examined glucose tolerance, post-challenge insulin response, plasma C-reactive protein and blood pressure after 15 months on Paleolithic diet in comparison with a cereal based swine feed.
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| 15. |
- Kacerovsky-Bielesz, Gertrud, et al.
(författare)
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A Single Nucleotide Polymorphism Associates With the Response of Muscle ATP Synthesis to Long-Term Exercise Training in Relatives of Type 2 Diabetic Humans
- 2012
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Ingår i: Diabetes Care. - : American Diabetes Association. - 1935-5548 .- 0149-5992. ; 35:2, s. 350-357
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Tidskriftsartikel (refereegranskat)abstract
- OBJECTIVE-Myocellular ATP synthesis (fATP) associates with insulin sensitivity in first-degree relatives of subjects with type 2 diabetes. Short-term endurance training can modify their fATP and insulin sensitivity. This study examines the effects of moderate long-term exercise using endurance or resistance training in this cohort. RESEARCH DESIGN AND METHODS-A randomized, parallel-group trial tested 16 glucose-tolerant nonobese relatives (8 subjects in the endurance training group and 8 subjects in the resistance training group) before and after 26 weeks of endurance or resistance training. Exercise performance was assessed from power output and oxygen uptake (VO2) during incremental tests and from maximal torque of knee flexors (MaxT(flex)) and extensors (MaxT(ext)) using isokinetic dynamometry. fATP and ectopic lipids were measured with H-1/P-31 magnetic resonance spectroscopy. RESULTS Endurance training increased power output and VO2 by 44 and 30%, respectively (both P < 0.001), whereas resistance training increased MaxT(ext) and MaxT(flex) by 23 and 40%, respectively (both P < 0.001). Across all groups, insulin sensitivity (382 +/- 90 vs. 389 +/- 40 mL.min.m(-2)) and ectopic lipid contents were comparable after exercise training. However, 8 of 16 relatives had 26% greater fATP, increasing from 9.5 +/- 2.3 to 11.9 +/- 2.4 mu mol.mL(-1).m(-1) (P < 0.05). Six of eight responders were carriers of the G/G single nucleotide polymorphism rs540467 of the NDUFB6 gene (P = 0.019), which encodes a subunit of mitochondrial complex I. CONCLUSIONS-Moderate exercise training for 6 months does not necessarily improve insulin sensitivity but may increase ATP synthase flux. Genetic predisposition can modify the individual response of the ATP synthase flux independently of insulin sensitivity.
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| 16. |
- Kacerovsky-Bielesz, Gertrud, et al.
(författare)
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Short-Term Exercise Training Does Not Stimulate Skeletal Muscle ATP Synthesis in Relatives of Humans With Type 2 Diabetes
- 2009
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Ingår i: Diabetes. - : American Diabetes Association. - 1939-327X .- 0012-1797. ; 58:6, s. 1333-1341
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Tidskriftsartikel (refereegranskat)abstract
- OBJECTIVE-We tested the hypothesis that short-term exercise training improves hereditary insulin resistance by stimulating ATP synthesis and investigated associations With gene polymorphisms. RESEARCH DESIGN AND METHODS-We studied 24 nono-bese first-degree relatives of type 2 diabetic patients and 12 control subjects at rest, and 48 h after three bouts of exercise. In addition to measurements of oxygen uptake and insulin sensitivity (oral glucose tolerance test), ectopic lipids and mitochondrial ATP synthesis were assessed using H-1 and P-31 magnetic resonance spectroscopy, respectively. They were genotyped for polymorphisms in genes regulating mitochondrial function, PPARGC1A (rs8192678) and NDUFB6 (rs540467). RESULTS-Relatives had slightly lower (P = 0.012) insulin sensitivity than control subjects. In control subjects, ATP synthase flux rose by 18% (P = 0.0001), being 23% higher (P = 0.002) than that in relatives after exercise training. Relatives responding to exercise training with increased ATP synthesis (+19%, P = 0.009) showed improved insulin sensitivity (P = 0.009) compared with those whose insulin sensitivity did not improve. A polymorphism in the NDUFB6 gene from respiratory chain complex I related to ATP synthesis (P = 0.02) and insulin Sensitivity response to exercise training (P = 0.05). ATP synthase flux correlated with O-2 uptake and insulin sensitivity. CONCLUSIONS-The ability of short-term exercise to stimulate ATP production distinguished individuals with improved insulin sensitivity from those whose insulin sensitivity did not improve. lit addition, the NDUFB6 gene polymorphism appeared to modulate this adaptation. This finding suggests that genes involved in mitochondrial function contribute to the response of ATP synthesis to exercise training. Diabetes 58:1333-1341, 2009
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| 17. |
- Kvist Reimer, Martina, et al.
(författare)
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Dose-dependent inhibition by ghrelin of insulin secretion in the mouse.
- 2003
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Ingår i: Endocrinology. - : The Endocrine Society. - 0013-7227 .- 1945-7170. ; 144:3, s. 916-921
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Tidskriftsartikel (refereegranskat)abstract
- Ghrelin is produced by stomach oxyntic cells and thought to be involved in the regulation of body weight and food intake. We demonstrate here that the peptide inhibits insulin secretion from overnight-incubated mouse islets in the presence of 8.3, 11.1, and 22.2 mmol/liter glucose. Ghrelin was most efficient at 1 nmol/liter and its effect disappeared by raising the dose more than 25 nmol/liter. Also, insulin secretion in the presence of high K+ concentrations (20 mmol/liter) was inhibited by ghrelin. Furthermore, when administered iv to mice together with glucose (1 g/kg), ghrelin (50 nmol/kg) inhibited both the rapid 1-min insulin response (364 ± 90 vs. 985 ± 114 pmol/liter in controls, P < 0.001) and the area under the 50 min curve of insulin concentration (12.6 ± 1.2 vs. 15.6 ± 1.2 nmol/liter × 50 min; P = 0.046) without affecting the glucose disposal rate, insulin sensitivity or glucose effectiveness, i.e. glucose disposal independent from any dynamic change in insulin. The insulinostatic effect of ghrelin was inversely related to insulin sensitivity. In contrast, ghrelin had no influence at the lower dose of 5 nmol/kg and only slightly inhibited insulin secretion at the higher dose of 150 nmol/kg. These findings therefore show that ghrelin inhibits glucose-stimulated insulin secretion in the mouse. The effect is dependent on the dose and elicited on distal signaling steps in islet cells. The results suggest that the islet β-cells are targets for ghrelin.
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| 18. |
- Lindgren, Ola, et al.
(författare)
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Incretin Effect after Oral Amino Acid Ingestion in Humans.
- 2015
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Ingår i: Journal of Clinical Endocrinology and Metabolism. - : The Endocrine Society. - 1945-7197 .- 0021-972X. ; 100:3, s. 1172-1176
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Tidskriftsartikel (refereegranskat)abstract
- Context: The incretin effect is the augmented insulin secretion by oral versus intravenous glucose at matching glucose levels. We previously demonstrated an augmented insulin secretion when fat is given orally rather than intravenously, suggesting an incretin effect also after fat. However, whether there is an incretin effect is also present after amino acid ingestion is not known. Objective: To explore insulin secretion and islet hormones after oral and intravenous amino acid administration at matched total amino acid concentrations in healthy subjects. Design: Amino acid mixture (Vaminolac(R)) was administered orally or intravenously at a rate resulting in matching total amino acid concentrations to twelve male volunteers with age 22.5±1.4 yr and BMI 22.4±1.4 kg/m(2), who had no history of diabetes. Main outcome measures: Area under the 120 min curve (AUC) for insulin, C-peptide, glucagon, intact and total glucagon like peptide-1 (GLP-1) and glucose-dependent insulinotropic polypeptide (GIP) and insulin secretory rate and insulin clearance. Results: Insulin, C-peptide and glucagon levels increased after both oral and intravenous administration, but insulin secretion was 25% higher after oral than after intravenous amino acid challenges (P=0.006), whereas there was no significant difference in the glucagon response. Intact and total GIP rose after oral but not after intravenous amino acid administration, whereas intact and total GLP-1 levels did not change significantly in either test. Conclusion: Oral amino acid mixture ingestion elicits a stronger insulin secretory response than intravenous amino acid at matching amino acid levels and that this is associated with increased GIP level, suggesting that an incretin effect exists also after oral amino acids, possibly mediated by GIP.
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| 19. |
- Lindgren, Ola, et al.
(författare)
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Incretin Hormone and Insulin Responses to Oral Versus Intravenous Lipid Administration in Humans.
- 2011
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Ingår i: The Journal of clinical endocrinology and metabolism. - : The Endocrine Society. - 1945-7197 .- 0021-972X. ; 96, s. 2519-2524
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Tidskriftsartikel (refereegranskat)abstract
- Context: The incretin effect is responsible for the higher insulin response to oral glucose than to iv glucose at matching glucose levels. It is not known whether this effect is restricted to glucose only. Objective: The aim of the study was to examine whether insulin and incretin hormone responses are higher after oral vs. iv challenge of a lipid emulsion with matching triglyceride levels in humans. Design, Settings, and Participants: A lipid emulsion (Intralipid) was administered orally (3 ml/kg) or iv (variable infusion rates to match triglyceride levels after oral ingestion) in healthy lean males (n = 12) at a University Clinical Research Unit. Samples were collected during 300 min. Main Outcome Measures: We measured the suprabasal area under the curve for insulin, glucagon-like peptide-1 (GLP-1), glucose-dependent insulinotropic polypeptide (GIP), and the insulin secretory rate based on C-peptide levels by deconvolution. Results: Triglyceride levels increased similarly after oral and iv lipid; also, glucose and free fatty acid levels were similar in the two tests. Oral lipid elicited a clear insulin and C-peptide response, whereas no insulin or C-peptide responses were observed during iv lipid. Total and intact GIP and GLP-1 levels both increased after oral lipid administration but were not significantly altered after iv lipid. Conclusions: At matching triglyceride levels and with no difference in glucose and free fatty acid levels, oral lipid ingestion but not iv lipid infusion elicits a clear insulin response in association with increased GIP and GLP-1 concentrations. This may suggest that the incretin hormones also contribute to the islet response to noncarbohydrate nutrients.
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| 20. |
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| 21. |
- Morettini, Micaela, et al.
(författare)
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Hepatic and extrahepatic insulin clearance in mice with double deletion of glucagon-like peptide-1 and glucose-dependent insulinotropic polypeptide receptors
- 2021
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Ingår i: Biomedicines. - : MDPI AG. - 2227-9059. ; 9:8
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Tidskriftsartikel (refereegranskat)abstract
- The aim of this study was to investigate whether incretins, at physiological levels, affect hepatic and/or extrahepatic insulin clearance. Hepatic and extrahepatic insulin clearance was studied in 31 double incretin receptor knockout (DIRKO) and 45 wild-type (WT) mice, which underwent an Intravenous Glucose Tolerance Test (IVGTT). A novel methodology based on mathematical modeling was designed to provide two sets of values (FEL-P1, CLP-P1; FEL-P2, CLP-P2 ) accounting for hepatic and extrahepatic clearance in the IVGTT first and second phases, respectively, plus the respective total clearances, CLT-P1 and CLT-P2 . A statistically significant difference between DIRKO and WT was found in CLT-P1 (0.61 [0.48–0.82] vs. 0.51 [0.46–0.65] (median [interquartile range]); p = 0.02), which was reflected in the peripheral component, CLP-P1 (0.18 [0.13–0.27] vs. 0.15 [0.11–0.22]; p = 0.04), but not in the hepatic component, FEL-P1 (29.7 [26.7–34.9] vs. 28.9 [25.7–32.0]; p = 0.18). No difference was detected between DIRKO and WT in CLT-P2 (1.38 [1.13–1.75] vs. 1.69 [1.48–1.87]; p = 0.10), neither in CLP-P2 (0.72 [0.64–0.81] vs. 0.79 [0.69–0.87]; p = 0.27) nor in FEL-P2 (37.8 [35.1–43.1] vs. 39.8 [35.8–44.2]; p = 0.46). In conclusion, our findings suggest that the higher insulin clearance observed in DIRKO compared with WT during the IVGTT first phase may be due to its extrahepatic component.
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| 22. |
- Morettini, Micaela, et al.
(författare)
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Mathematical Model of Glucagon Kinetics for the Assessment of Insulin-Mediated Glucagon Inhibition During an Oral Glucose Tolerance Test
- 2021
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Ingår i: Frontiers in Endocrinology. - : Frontiers Media SA. - 1664-2392. ; 12
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Tidskriftsartikel (refereegranskat)abstract
- Glucagon is secreted from the pancreatic alpha cells and plays an important role in the maintenance of glucose homeostasis, by interacting with insulin. The plasma glucose levels determine whether glucagon secretion or insulin secretion is activated or inhibited. Despite its relevance, some aspects of glucagon secretion and kinetics remain unclear. To gain insight into this, we aimed to develop a mathematical model of the glucagon kinetics during an oral glucose tolerance test, which is sufficiently simple to be used in the clinical practice. The proposed model included two first-order differential equations -one describing glucagon and the other describing C-peptide in a compartment remote from plasma - and yielded a parameter of possible clinical relevance (i.e., SGLUCA(t), glucagon-inhibition sensitivity to glucose-induced insulin secretion). Model was validated on mean glucagon data derived from the scientific literature, yielding values for SGLUCA(t) ranging from -15.03 to 2.75 (ng of glucagon·nmol of C-peptide-1). A further validation on a total of 100 virtual subjects provided reliable results (mean residuals between -1.5 and 1.5 ng·L-1) and a negative significant linear correlation (r = -0.74, p < 0.0001, 95% CI: -0.82 – -0.64) between SGLUCA(t) and the ratio between the areas under the curve of suprabasal remote C-peptide and glucagon. Model reliability was also proven by the ability to capture different patterns in glucagon kinetics. In conclusion, the proposed model reliably reproduces glucagon kinetics and is characterized by sufficient simplicity to be possibly used in the clinical practice, for the estimation in the single individual of some glucagon-related parameters.
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| 23. |
- Ohlsson, Lena, et al.
(författare)
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Glucose-lowering effect of the DPP-4 inhibitor sitagliptin after glucose and non-glucose macronutrient ingestion in non-diabetic subjects.
- 2013
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Ingår i: Diabetes, Obesity and Metabolism. - : Wiley. - 1462-8902. ; 15:6, s. 531-537
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Tidskriftsartikel (refereegranskat)abstract
- AIM: Recent studies suggest that the incretin concept is not restricted to glucose ingestion but relevant also after non-glucose macronutrient administration. We therefore hypothesized that raising incretin hormones reduces circulating glucose after both glucose and non-glucose macronutrient ingestion in healthy subjects. MATERIAL AND METHODS: Twelve healthy subjects received the dipeptidyl peptidase-4 inhibitor sitagliptin (100mg) or placebo before ingestion of glucose, fat (olive oil) or protein mix in equicaloric amounts (8 kcal/kg) plus paracetamol (1g). The 120-min AUC of intact GLP-1, glucose, insulin, C-peptide, glucagon and paracetamol, and model-derived insulin secretion (ISR), insulin sensitivity, insulin clearance and glucose absorption were measured. RESULTS: The increased plasma intact GLP-1 levels after each macronutrient was augmented by sitagliptin. This was associated with a robust lowering of glucose: glucose excursion after oral glucose was diminished, and glucose fell below baseline after oral fat and protein. In spite of lower glucose, AUC(C) (-peptide) and ISR did not differ significantly between sitagliptin and placebo after any macronutrient. AUC(glucagon) , insulin sensitivity and insulin clearance were also not different between sitagliptin and placebo. Glucose absorption after oral glucose was reduced by sitagliptin, whereas AUC(paracetamol) was not statistically different between sitagliptin and placebo. CONCLUSIONS: Physiological elevation of intact GLP-1 levels after ingestion of glucose and non-glucose macronutrients is robustly glucose-lowering in healthy subjects. Hence, the incretin concept is not restricted to glucose ingestion in normal physiology. The glucose-lowering action of sitagliptin at these low glucose levels in healthy subjects may have complex mechanisms, involving both islet-dependent and islet-independent mechanisms.
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| 24. |
- Omar, Bilal, et al.
(författare)
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Differential Development of Glucose Intolerance and Pancreatic Islet Adaptation in Multiple Diet Induced Obesity Models
- 2012
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Ingår i: Nutrients. - : MDPI AG. - 2072-6643. ; 4:10, s. 1367-1381
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Tidskriftsartikel (refereegranskat)abstract
- Background: The C57BL/6 mouse fed a high fat diet is a common and valuable model in experimental studies of obesity and type 2 diabetes (T2D). Different high fat diets are used and in order to determine which diet produces a model most accurately resembling human T2D, they need to be compared head-to-head. Methods: Four different diets, the 60% high fat diet (HFD) and the 58% high fat-high sucrose Surwit diet (HFHS) and their respective controls, were compared in C57BL/6J mice using glucose tolerance tests (IVGTT) and the euglycemic clamp. Results: Mice fed a HFD gained more weight than HFHS fed mice despite having similar energy intake. Both high fat diet models were glucose intolerant after eight weeks. Mice fed the HFD had elevated basal insulin, which was not seen in the HFHS group. The acute insulin response (AIR) was unchanged in the HFD group, but slightly increased in the HFHS diet group. The HFHS diet group had a threefold greater total insulin secretion during the IVGTT compared to its control, while no differences were seen in the HFD group. Insulin sensitivity was decreased fourfold in the HFD group, but not in the HFHS diet group. Conclusion: The HFD and HFHS diet models show differential effects on the development of insulin resistance and beta cell adaptation. These discrepancies are important to acknowledge in order to select the appropriate diet for specific studies.
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| 25. |
- Omar, Bilal, et al.
(författare)
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Impact of glucose dosing regimens on modeling of glucose tolerance and β-cell function by intravenous glucose tolerance test in diet-induced obese mice.
- 2014
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Ingår i: Physiological Reports. - : Wiley. - 2051-817X. ; 2:5
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Tidskriftsartikel (refereegranskat)abstract
- Insulin sensitivity declines in overweight and obese individuals and, under normal conditions, insulin secretion adaptively increases which in healthy non-diabetic subjects maintains normal glycemia. This adaptation is best described by the disposition index derived from modeling of insulin and glucose data from an intravenous glucose tolerance testing (IVGTT). One caveat of the IVGTT is that basing the glucose dose on the individual total body weight can result in large differences in the amount of glucose given to lean and obese individuals. The effect this has on determination of insulin sensitivity and β-cell function is unknown. In this study, we therefore evaluated alternative glucose dosing regimens for determination of the impact of glucose dosing on measures of β-cell function in normal and diet-induced obese (DIO) mice. The glucose dosing regimens used for the IVGTT were 0.35 mg per kg total body weight (BW) or per kg lean BW or a fixed glucose dose based on the average BW for all experimental mice. Each regimen detected a similar decrease in insulin sensitivity in DIO mice. The different glucose dosing regimens gave, however, diverging results in regard to glucose elimination and the acute insulin response. Thus, the fixed-dose regimen was the only that revealed impairment of glucose elimination, whereas dosing according to total BW was the only regimen which showed significant increases in acute insulin response in DIO mice. The fixed-dose glucose dosing regimen was the only that revealed a significant decline in the disposition index value in DIO mice, which is characteristic of type 2 diabetes in humans. Our results therefore show that using different glucose dosing regimens during IVGTT in DIO mice one can model different aspects of physiology which are similar to prediabetes and type 2 diabetes in humans, with the fixed-dose regimen producing a phenotype that most closely resembles human type 2 diabetes.
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| 26. |
- Ovlund, Tina, et al.
(författare)
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Impact of Incretin Hormone Receptors on Insulin-Independent Glucose Disposal in Model Experiments in Mice
- 2021
-
Ingår i: Frontiers in Endocrinology. - : Frontiers Media SA. - 1664-2392. ; 12
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Tidskriftsartikel (refereegranskat)abstract
- A large contribution to glucose elimination from the circulation is achieved by insulin-independent processes. We have previously shown that the two incretin hormones, glucose-dependent insulinotropic polypeptide (GIP) and glucagon-like peptide-1 (GLP-1) increase this process and, therefore, seem to contribute to glucose disposal both through this effect and through the classical incretin effect resulting in enhanced insulin levels. We have now explored in more detail the potential contribution by incretin hormone receptors to insulin-independent processes for glucose elimination. To that end, we have performed intravenous glucose tests (0.35g/kg) in C57BL/6J mice and analyzed glucose elimination rate and glucose effectiveness (i.e., insulin-independent glucose disposal, SG) in wildtype mice and in mice with genetic deletion of GIP receptors or GLP-1 receptors. We performed studies with or without complete blockade of insulin secretion by the drug diazoxide (25 mg/kg). The mice were anesthetized with a novel fentanyl citrate/fluanisone formulation, called Fluafent, together with midazolam. Initially we demonstrated that glucose and insulin data after intravenous and oral glucose were not different using this anesthesia compared to the previously commonly used combination of HypnormR and midazolam. The results show that SG was reduced in GLP-1 receptor knockout mice, whereas there was no difference between GIP receptor knockout mice and wildtype mice, and this was evident both under normal conditions and after complete inhibition of insulin secretion. The study therefore indicates that insulin-independent glucose elimination requires active GLP-1 receptors and thus that the two incretin hormone receptor types show dissociated relevance for this process.
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| 27. |
- Pacini, Giovanni, et al.
(författare)
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Assessing the Effect of Incretin Hormones and Other Insulin Secretagogues on Pancreatic Beta-Cell Function : Review on Mathematical Modelling Approaches
- 2022
-
Ingår i: Biomedicines. - : MDPI AG. - 2227-9059. ; 10:5
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Forskningsöversikt (refereegranskat)abstract
- Mathematical modelling in glucose metabolism has proven very useful for different reasons. Several models have allowed deeper understanding of the relevant physiological and pathophysiological aspects and promoted new experimental activity to reach increased knowledge of the biological and physiological systems of interest. Glucose metabolism modelling has also proven useful to identify the parameters with specific physiological meaning in single individuals, this being relevant for clinical applications in terms of precision diagnostics or therapy. Among those model-based physiological parameters, an important role resides in those for the assessment of different functional aspects of the pancreatic beta cell. This study focuses on the mathematical models of incretin hormones and other endogenous substances with known effects on insulin secretion and beta-cell function, mainly amino acids, non-esterified fatty acids, and glucagon. We found that there is a relatively large number of mathematical models for the effects on the beta cells of incretin hormones, both at the cellular/organ level or at the higher, whole-body level. In contrast, very few models were identified for the assessment of the effect of other insulin secretagogues. Given the opportunities offered by mathematical modelling, we believe that novel models in the investigated field are certainly advisable.
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| 28. |
- Pacini, Giovanni, et al.
(författare)
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Dissociated effects of glucose-dependent insulinotropic polypeptide vs glucagon-like peptide-1 on beta-cell secretion and insulin clearance in mice
- 2010
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Ingår i: Metabolism, Clinical and Experimental. - : Elsevier BV. - 1532-8600. ; 59:7, s. 988-992
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Tidskriftsartikel (refereegranskat)abstract
- Glucagon-like peptide-1 (GLP-1) and glucose-dependent insulinotropic polypeptide (GIP) potently augment insulin response to glucose. It is less known what their effects are insulin clearance, which also contributes to peripheral hyperinsulinemia observed after administration of incretins together with glucose. The aims of this study were the quantification of C-peptide secretion and the evaluation of insulin clearance after administration of GIP with glucose. This allows the assessment of GIP's effects on hyperinsulinemia. In addition, GIP's effects were compared with those of GLP-1. Anesthetized female NMRI mice were injected intravenously with glucose alone (1 g/kg, n = 35) or glucose together with GIP (50 mu g/kg, n = 12). Samples were taken through the following 50 minutes, and C-peptide and insulin concentrations were used to reconstruct C-peptide secretion rate and insulin clearance. In a previous study, GLP-1 (10 mu g/kg) was used in 12 mice; and we used those GLP-1 results to compare GIP effects with those of GLP-1. C-peptide secretion rate peaked at 1 minute after glucose injection, and the immediate part of the insulin-releasing process was markedly augmented by both incretin hormones (1-minute suprabasal increment secretory rate was 20 +/- 2 pmol/min for GIP and 28 +/- 2 pmol/min for GLP-1, vs only 9 +/- 1 pmol/min for glucose alone; P < .001). Until 10 minutes after administration, C-peptide secretion remained higher with incretins (P < .0001), whereas starting from 20 minutes, the 3 patterns were undistinguishable (P > .2). Insulin clearance, previously shown to be abridged by 46% with GLP-1, was reduced only by a nonsignificant (P = .27) 21% with GIP. This study thus shows that the 2 incretins markedly augment glucose-stimulated insulin secretion in mice by a preferential action on the immediate response to glucose of insulin secretion. However, the action of GIP is less effective than that of GLP-1. Insulin clearance with GIP is not significantly reduced. We conclude that GIP is less potent than GLP-1 in inducing glucose-stimulated hyperinsulinemia in the mouse. (C) 2010 Elsevier Inc. All rights reserved.
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| 29. |
- Pacini, Giovanni, et al.
(författare)
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Glucagon and GLP-1 exhibit no synergistic enhancement of glucose-stimulated insulin secretion in mice.
- 2015
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Ingår i: Peptides. - : Elsevier BV. - 1873-5169 .- 0196-9781. ; 71:Jun 26, s. 66-71
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Tidskriftsartikel (refereegranskat)abstract
- The combination of glucagon and glucagon-like peptide-1 (GLP-1) has been suggested as an approach to target obesity, since the two hormones have complementary action on body weight. We examined whether complementary action of the two hormones also exist on insulin secretion. Female C57BL/6 mice were injected intravenously with glucose with or without GLP-1, glucagon or the combination of GLP-1 and glucagon at three different dose levels. Furthermore, freshly isolated mouse islets were incubated for 30min in with the presence of 2.8, 11.1 or 16.7mmol/l glucose or with 11.1mmol/l glucose in the presence of 100 nmol/l glucagon and/or GLP-1. It was found that at 1min after glucose injection alone, insulin rose to a peak level and this peak, as well as the 50min area under the insulin curve (AUC insulin) were dose-dependently augmented by GLP-1 and glucagon. However, peak insulin with the two hormones together (with glucose) was not higher than after either single administration at any of the tested doses, i.e., no additive of synergistic action was observed by the combination on glucose-stimulated insulin secretion. Similar results were observed when calculating insulin for the whole test period. Also in vitro, both glucagon and GLP-1 augmented insulin secretion; however, there was no difference between the combined stimulation of insulin secretion by GLP-1 and glucagon together compared with either hormone alone. Insulin sensitivity did not exhibit significant changes from the glucose only condition. We conclude that the acute combined administration of the strongly insulinotropic GLP-1 and glucagon, both in vivo and in vitro, did not induce any additive or synergistic action on glucose-stimulated insulin secretion. This shows that the risk of a marked insulinotropic action when the two compounds are given together most likely does not result in increased risk of hypoglycemia.
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| 30. |
- Pacini, Giovanni, et al.
(författare)
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Glucagon-like peptide-1 and glucose-dependent insulinotropic peptide : effects alone and in combination on insulin secretion and glucose disappearance in mice
- 2017
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Ingår i: Physiological Reports. - : Wiley. - 2051-817X. ; 5:11
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Tidskriftsartikel (refereegranskat)abstract
- Glucagon-like peptide-1 (GLP-1) and glucose-dependent insulinotropic peptide (GIP) stimulate insulin secretion. They are both released after meal ingestion, and therefore they might cooperate in their actions. However, whether there is a cooperative action of the two incretins is not known. This study therefore investigated the effects on insulin secretion and glucose disappearance of GLP-1 and GIP when given together with intravenous glucose both alone and in combination in mice. Four different doses were used (0.003, 0.03, 0.3 and 3.0 nmol/kg), which ranged from subthreshold to maximal doses to stimulate first-phase insulin secretion as evident from initial dose–response studies. It was found that at 0.03 nmol/kg and higher doses, glucose-stimulated insulin secretion was augmented by both incretins. When they were given in combination, no further increase was observed, indicating no synergistic effect. Also, glucose disappearance rate was increased by 0.03 and 3.0 nmol/kg of the two incretins, both when they were given alone and in combination with, again, no synergy. Finally, glucose effectiveness (an index of noninsulin-mediated processes) was enhanced by the two incretins, in particular GIP. We also found that insulin-dependent and insulin-independent mechanisms contributed 38% and 62%, respectively, to glucose tolerance after glucose alone; with GIP, the contribution by noninsulin-dependent processes was remarkably dominant and with GLP-1, insulin-dependent processes were prevailing. In conclusion, GIP and GLP-1 stimulate insulin secretion and glucose effectiveness in mice with no synergistic action, but with a dissociated contributory effector on glucose disposal: with GLP-1 being more active on insulin-dependent processes and GIP more active on noninsulin-dependent processes.
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| 31. |
- Pacini, Giovanni, et al.
(författare)
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Reappraisal of the intravenous glucose tolerance index for a simple assessment of insulin sensitivity in mice
- 2009
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Ingår i: American Journal of Physiology: Regulatory, Integrative and Comparative Physiology. - : American Physiological Society. - 0363-6119 .- 1522-1490. ; 296:5, s. 1316-1324
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Tidskriftsartikel (refereegranskat)abstract
- Pacini G, Ahren M, Ahren B. Reappraisal of the intravenous glucose tolerance index for a simple assessment of insulin sensitivity in mice. Am J Physiol Regul Integr Comp Physiol 296: R1316-R1324, 2009. First published February 11, 2009; doi: 10.1152/ajpregu.90575.2008.- Mice are increasingly used in studies where measuring insulin sensitivity (IS) is a common procedure. The glucose clamp is labor intensive, cannot be used in large numbers of animals, cannot be repeated in the same mouse, and has been questioned as a valid tool for IS in mice; thus, the minimal model with 50-min intravenous glucose tolerance test (IVGTT) data was adapted for studies in mice. However, specific software and particular ability was needed. The aim of this study was to establish a simple procedure for evaluating IS during IVGTT in mice (CSI). IVGTTs (n = 520) were performed in NMRI and C57BL/6J mice (20-25g). After glucose injection (1 g/kg), seven samples were collected for 50 min for glucose and insulin measurements, analyzed with a minimal model that provided the validated reference IS (S-perpendicular to). By using the regression CS perpendicular to = alpha(1) + alpha(2) x K-G/AUC(D), where K-G is intravenous glucose tolerance index and AUC(D) is the dynamic area under the curve, IS was calculated in 134 control animals randomly selected (regression CSI vs. S-I: r = 0.66, P < 0.0001) and yielded alpha(1) = 1.93 and alpha(2) = 0.24. KG is the slope of log (glucose(5-20)) and AUCD is the mean dynamic area under insulin curve in the IVGTT. By keeping fixed alpha(1) and alpha(2), CSI was validated in 143 control mice (4.7 +/- 0.2 min . mu U- . ml(-1), virtually identical to S-I: 4.7 +/- 0.3, r = 0.89, P < 0.0001); and in 123 mice in different conditions: transgenic, addition of neuropeptides, incretins, and insulin (CSI: 6.0 +/- 0.4 vs. SI: 6.1 +/- 0.4, r = 0.94, P < 0.0001). In the other 120 animals, CSI revealed its ability to segregate different categories, as does S-I. This easily usable formula for calculating CSI overcomes many experimental obstacles and may be a simple alternative to more complex procedures when large numbers of mice or repeated experiments in the same animals are required.
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| 32. |
- Pacini, Giovanni, et al.
(författare)
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The dual incretin co-agonist tirzepatide increases both insulin secretion and glucose effectiveness in model experiments in mice
- 2024
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Ingår i: Peptides. - 0196-9781. ; 171
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Tidskriftsartikel (refereegranskat)abstract
- Tirzepatide is a dual GIP and GLP-1 receptor co-agonist which is approved for glucose-lowering therapy in type 2 diabetes. Here, we explored its effects on beta cell function, insulin sensitivity and insulin-independent glucose elimination (glucose effectiveness) in normal mice. Anesthetized female C57/BL/6 J mice were injected intravenously with saline or glucose (0.125, 0.35 or 0.75 g/kg) with or without simultaneous administration of synthetic tirzepatide (3 nmol/kg). Samples were taken at 0, 1, 5, 10, 20 and 50 min. Glucose elimination rate was estimated by the percentage reduction in glucose from min 5 to min 20 (KG). The 50 min areas under the curve (AUC) for insulin and glucose were determined. Beta cell function was assessed as AUCinsulin divided by AUCglucose. Insulin sensitivity (SI) and glucose effectiveness (SG) were determined by minimal model analysis of the insulin and glucose data. Tirzepatide glucose-dependently reduced glucose levels and increased insulin levels. The slope for the regression of AUCinsulin versus AUCglucose was increased 7-fold by tirzepatide from 0.014 ± 0.004 with glucose only to 0.099 ± 0.016 (P < 0.001). SI was not affected by tirzepatide, whereas SG was increased by 78% (P < 0.001). The increase in SG contributed to an increase in KG by 74 ± 4% after glucose alone and by 67 ± 8% after glucose+ tirzepatide, whereas contribution by SI times AUCinsulin insulin (i.e., disposition index) was 26 ± 4% and 33 ± 8%, respectively. In conclusion, tirzepatide stimulates both insulin secretion and glucose effectiveness, with stimulation of glucose effectiveness being the prominent process to reduce glucose.
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| 33. |
- Persson, Kristin, et al.
(författare)
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Islet function phenotype in gastrin-releasing Peptide receptor gene-deficient mice.
- 2002
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Ingår i: Endocrinology. - : The Endocrine Society. - 0013-7227 .- 1945-7170. ; 143:10, s. 3717-3726
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Tidskriftsartikel (refereegranskat)abstract
- Gastrin-releasing peptide (GRP) is an islet neuropeptide that stimulates insulin secretion. To explore whether islet GRP contributes to neurally mediated insulin secretion, we studied GRP receptor (GRPR)-deleted mice. By using RT-PCR we showed that GRPR mRNA is expressed in islets of wild-type mice, but is lost in GRPR-deleted mice. Functional studies revealed that GRP potentiates glucose-stimulated insulin secretion in wild-type animals, but not in GRPR-deleted mice. This shows that GRPR is the receptor subtype mediating GRP-induced insulin secretion and that GRPR-deleted mice are tools for studying the physiological role of islet GRP. We found that GRPR-deleted mice display 1) augmentation of the insulin response to glucose by a mechanism inhibited by ganglionic blockade; 2) increased insulin responsiveness also to the cholinergic agonist carbachol, but not to arginine; 3) impaired insulin and glucagon responses to autonomic nerve activation by 2-deoxyglucose; 4) normal islet adaptation to high fat-induced insulin resistance and fasting; and 5) normal islet cytoarchitecture, as revealed by immunocytochemistry of insulin and glucagon. In conclusion, 1) GRPR is the receptor subtype mediating the islet effects of GRP; 2) GRP contributes to insulin secretion induced by activation of the autonomic nerves; and 3) deletion of GRPR is compensated by increased cholinergic sensitivity.
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| 34. |
- Song, Gina, et al.
(författare)
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Glucagon increases insulin levels by stimulating insulin secretion without effect on insulin clearance in mice
- 2017
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Ingår i: Peptides. - : Elsevier BV. - 0196-9781. ; 88, s. 74-79
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Tidskriftsartikel (refereegranskat)abstract
- Circulating insulin is dependent on a balance between insulin appearance through secretion and insulin clearance. However, to what extent changes in insulin clearance contribute to the increased insulin levels after glucagon administration is not known. This study therefore assessed and quantified any potential effect of glucagon on insulin kinetics in mice. Prehepatic insulin secretion in mice was first estimated following glucose (0.35 g/kg i.v.) and following glucose plus glucagon (10 μg/kg i.v.) using deconvolution of plasma C-peptide concentrations. Plasma concentrations of glucose, insulin, and glucagon were then measured simultaneously in individual mice following glucose alone or glucose plus glucagon (pre dose and at 1, 5, 10, 20 min post). Using the previously determined insulin secretion profiles and the insulin concentration-time measurements, a population modeling analysis was applied to estimate the one-compartment kinetics of insulin disposition with and without glucagon. Glucagon with glucose significantly enhanced prehepatic insulin secretion (Cmax and AUC0-20) compared to that with glucose alone (p < 0.0001). From the modeling analysis, the population mean and between-animal SD of insulin clearance was 6.4 ± 0.34 mL/min for glucose alone and 5.8 ± 1.5 mL/min for glucagon plus glucose, with no significant effect of glucagon on mean insulin clearance. Therefore, we conclude that the enhancement of circulating insulin after glucagon administration is solely due to stimulated insulin secretion.
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| 35. |
- Stadler, Marietta, et al.
(författare)
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Effects of smoking cessation on beta cell function, insulin sensitivity, body weight and appetite.
- 2014
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Ingår i: European journal of endocrinology / European Federation of Endocrine Societies. - 1479-683X. ; 170, s. 219-227
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Tidskriftsartikel (refereegranskat)abstract
- Objective To stop smoking is commonly associated with significant weight gain, but the mechanisms for this are poorly understood. We assessed the effects of smoking cessation on body weight, insulin sensitivity, β-cell function, and appetite. Subjects and methods Twenty-seven long-term smokers (n=27; nine females/18 males, 28±1 years, 22.9±0.6kg/m2) attending an ambulatory smoking cessation program in a community hospital in Vienna, Austria were examined at baseline (Visit A; still smoking) and after a minimum of 3 months of smoking abstinence (Visit B; n=14); relapsed smokers were not followed up. Participants underwent 3-h oral glucose tolerance tests and body composition measurements at each study visit. Fasting (QUICKI) and dynamic (oral glucose insulin sensitivity (OGIS)) insulin sensitivity and β-cell secretion (insulinogenic index 140 (IGI40)) were calculated. Food intake was quantified with a free choice buffet. Fasting plasma concentrations of neuropeptide-Y (NPY), peptide-YY (PYY), glucagon-like peptide 1 (GLP1), leptin, ghrelin, and visfatin were measured. Results After >3 months' smoking abstinence, body weight, and fat mass were increased (+4 and +22% respectively, P<0.05) and fasting insulin sensitivity deteriorated (QUICKI: post, 0.37±0.02 vs baseline, 0.41±0.2; P<0.05), while OGIS remained unchanged throughout. IGI40 increased by 31% after >3 months' smoking abstinence (P<0.01). Carbohydrate ingestion increased after stopping smoking (P<0.05). NPY fasting levels were increased after >3 months (P<0.05), PYY, GLP1, leptin, ghrelin, and visfatin were unchanged. Conclusion Smoking cessation is associated with transient metabolic changes including increased β-cell secretion in response to glucose and fasting insulin resistance. These alterations may be associated with or contribute to the body weight gain after smoking cessation.
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| 36. |
- Sörhede Winzell, Maria, et al.
(författare)
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Beta-Cell-Targeted Expression of a Dominant-Negative Mutant of Hepatocyte Nuclear Factor-1{alpha} in Mice: Diabetes Model with {beta}-Cell Dysfunction Partially Rescued by Nonglucose Secretagogues.
- 2004
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Ingår i: Diabetes. - 1939-327X. ; 53:suppl_3, s. 92-96
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Tidskriftsartikel (refereegranskat)abstract
- We studied islet function in mice with beta-cell-targeted expression of a dominant-negative mutant of hepatocyte nuclear factor (HNF)-1alpha. At age 2-3 months, anesthetized transgenic and wild-type male mice underwent an intravenous glucose (1 g/kg) tolerance test (IVGTT). It was found that transgenic mice had an abolished insulin response in association with severe glucose intolerance. In other tests, the 5-min insulin response to intravenous arginine was impaired by 79% (P=0.032) and the 15-min insulin response to gastric glucose was suppressed by 97% (P=0.006). In islets incubated for 60 min, the insulin response to glucose (3.3-22.2 mmol/l) was impaired by >80% in transgenic mice. In contrast, insulin responses to nonglucose secretagogues were only partially suppressed (to GLP-1 [100 nmol/l] by 40%, to carbachol [1 micromol/l] by 20%, and to palmitate [0.5 mmol/l] by 15%), whereas the response to depolarization by KCl (50 mmol/l) was not reduced. Finally, the IVGTT data insulin sensitivity in transgenic mice was not significantly different from that of wild-type mice. Thus, mice with targeted suppression of beta-cell HNF-1alpha represent a good diabetes model exhibiting severely impaired insulin secretion after glucose with marked glucose intolerance. In contrast, the insulin responses to nonglucose stimuli are not suppressed when the islet insulin content is taken into account.
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| 37. |
- Sörhede Winzell, Maria, et al.
(författare)
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Insulin secretion after dietary supplementation with conjugated linoleic acids and n-3 polyunsaturated fatty acids in normal and insulin-resistant mice.
- 2006
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Ingår i: American Journal of Physiology: Endocrinology and Metabolism. - : American Physiological Society. - 1522-1555 .- 0193-1849. ; 290:2, s. 347-354
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Tidskriftsartikel (refereegranskat)abstract
- Insulin secretion after dietary supplementation with conjugated linoleic acids and n-3 polyunsaturated fatty acids in normal and insulin-resistance mice. Am J Physiol Endocrinol Metab 290: E347-E354, 2006. First published September 27, 2005; doi:10.1152/ajpendo.00163.2005.-Conjugated linoleic acids (CLAs) and n-3 polyunsaturated fatty acids (PUFAs) improve insulin sensitivity in insulin-resistant rodents. However, the effects of these fatty acids on insulin secretion are not known but are of importance to completely understand their influence on glucose homeostasis. We therefore examined islet function after dietary supplementation consisting of 1% CLAs in combination with 1% n-3 enriched PUFAs for 12 wk to mice on a normal diet and to insulin-resistant mice fed a high-fat diet (58% fat). In the mice fed a normal diet, CLA/PUFA supplementation resulted in insulin resistance associated with low plasma adiponectin levels and low body fat content. Intravenous and oral glucose tolerance tests revealed a marked increase in insulin secretion, which nevertheless was insufficient to counteract the insulin resistance, resulting in glucose intolerance. In freshly isolated islets from mice fed the normal diet, both basal and glucose-stimulated insulin secretion were adaptively augmented by CLA/PUFA, and at a high glucose concentration this was accompanied by elevated glucose oxidation. In contrast, in high-fat-fed mice, CLA/PUFA did not significantly affect insulin secretion, insulin resistance, or glucose tolerance. It is concluded that dietary supplementation of CLA/PUFA in mice fed the normal diet augments insulin secretion, partly because of increased islet glucose oxidation, but that this augmentation is insufficient to counterbalance the induction of insulin resistance, resulting in glucose intolerance. Furthermore, the high-fat diet partly prevents the deleterious effects of CLA/PUFA, but this dietary supplementation was not able to counteract high-fat-diet-induced insulin resistance.
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| 38. |
- Tura, Andrea, et al.
(författare)
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Four-Point Preprandial Self-Monitoring of Blood Glucose for the Assessment of Glycemic Control and Variability in Patients with Type 2 Diabetes Treated with Insulin and Vildagliptin.
- 2015
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Ingår i: International Journal of Endocrinology. - : Hindawi Limited. - 1687-8337 .- 1687-8345. ; 2015
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Tidskriftsartikel (refereegranskat)abstract
- The study explored the utility of four-point preprandial glucose self-monitoring to calculate several indices of glycemic control and variability in a study adding the DPP-4 inhibitor vildagliptin to ongoing insulin therapy. This analysis utilized data from a double-blind, randomized, placebo-controlled crossover study in 29 patients with type 2 diabetes treated with vildagliptin or placebo on top of stable insulin dose. During two 4-week treatment periods, self-monitoring of plasma glucose was undertaken at 4 occasions every day. Glucose values were used to assess several indices of glycemic control quality, such as glucose mean, GRADE, M-VALUE, hypoglycemia and hyperglycemia index, and indices of glycemic variability, such as standard deviation, CONGA, J-INDEX, and MAGE. We found that vildagliptin improved the glycemic condition compared to placebo: mean glycemic levels, and both GRADE and M-VALUE, were reduced by vildagliptin (P < 0.01). Indices also showed that vildagliptin reduced glycemia without increasing the risk for hypoglycemia. Almost all indices of glycemic variability showed an improvement of the glycemic condition with vildagliptin (P < 0.02), though more marked differences were shown by the more complex indices. In conclusion, the study shows that four-sample preprandial glucose self-monitoring is sufficient to yield information on the vildagliptin effects on glycemic control and variability.
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| 39. |
- Tura, Andrea, et al.
(författare)
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Glucagon and insulin secretion, insulin clearance, and fasting glucose in GIP receptor and GLP-1 receptor knockout mice
- 2019
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Ingår i: American Journal of Physiology: Regulatory, Integrative and Comparative Physiology. - : American Physiological Society. - 0363-6119 .- 1522-1490. ; 316:1, s. 27-37
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Tidskriftsartikel (refereegranskat)abstract
- It is not known whether GIP receptor and GLP-1 receptor knockout (KO) mice have perturbations in glucagon secretion or insulin clearance, and studies on impact on fasting glycemia have previously been inconsistent in these mice. We therefore studied glucagon secretion after oral whey protein (60 mg) and intravenous arginine (6.25 mg), insulin clearance after intravenous glucose (0.35 g/kg) and fasting glucose, insulin, and glucagon levels after standardized 5-h fasting in female GIP receptor and GLP-1 receptor KO mice and their wild-type (WT) littermates. Compared with WT controls, GIP receptor KO mice had normal glucagon responses to oral protein and intravenous arginine, except for an enhanced 1-min response to arginine, whereas glucagon levels after oral protein and intravenous arginine were enhanced in GLP-1 receptor KO mice. Furthermore, the intravenous glucose test revealed normal insulin clearance in both GIP receptor and GLP-1 receptor KO mice, whereas β-cell glucose sensitivity was enhanced in GIP receptor KO mice and reduced in GLP-1 receptor KO mice. Finally, GIP receptor KO mice had reduced fasting glucose (6.7 ± 0.1, n = 56, vs. 7.4 ± 0.1 mmol/l, n = 59, P = 0.001), whereas GLP-1 receptor KO mice had increased fasting glucose (9.1 ± 0.2, n = 44, vs. 7.7 ± 0.1 mmol/l, n = 41, P < 0.001). We therefore suggest that GIP has a limited role for glucagon secretion in mice, whereas GLP-1 is of importance for glucagon regulation, that GIP and GLP-1 are of importance for the regulation of β-cell function beyond their role as incretin hormones, and that they are both of importance for fasting glucose.
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| 40. |
- Tura, Andrea, et al.
(författare)
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Increased insulin clearance in mice with double deletion of glucagon-like peptide-1 and glucose-dependent insulinotropic polypeptide receptors
- 2018
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Ingår i: American Journal of Physiology - Regulatory Integrative and Comparative Physiology. - : American Physiological Society. - 0363-6119 .- 1522-1490. ; 314:5, s. 639-646
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Tidskriftsartikel (refereegranskat)abstract
- To establish whether incretin hormones affect insulin clearance, the aim of this study was to assess insulin clearance in mice with genetic deletion of receptors for both glucagon-like peptide-1 (GLP-1) and glucose-dependent insulinotropic polypeptide (GIP), so called double incretin receptor knockout mice (DIRKO). DIRKO (n = 31) and wild-type (WT) C57BL6J mice (n = 45) were intravenously injected with D-glucose (0.35 g/kg). Blood was sampled for 50 min and assayed for glucose, insulin, and C-peptide. Data were modeled to calculate insulin clearance; C-peptide kinetics was established after human C-peptide injection. Assessment of C-peptide kinetics revealed that C-peptide clearance was 1.66 ± 0.10 10–31/min. After intravenous glucose administration, insulin clearance during first phase insulin secretion was markedly higher in DIRKO than in WT mice (0.68 ± 0.06 10–3l/min in DIRKO mice vs. 0.54 ± 0.03 10–31/min in WT mice, P = 0.02). In contrast, there was no difference between the two groups in insulin clearance during second phase insulin secretion (P = 0.18). In conclusion, this study evaluated C-peptide kinetics in the mouse and exploited a mathematical model to estimate insulin clearance. Results showed that DIRKO mice have higher insulin clearance than WT mice, following intravenous injection of glucose. This suggests that incretin hormones reduce insulin clearance at physiological, nonstimulated levels.
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| 41. |
- Zhou, Alyssa, et al.
(författare)
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Glucagon clearance is regulated by nutritional state : Evidence from experimental studies in mice
- 2014
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Ingår i: Diabetologia. - : Springer Science and Business Media LLC. - 0012-186X .- 1432-0428. ; 57:4, s. 801-808
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Tidskriftsartikel (refereegranskat)abstract
- Aims/hypothesis: Given the importance of glucagon in the development of type 2 diabetes and as a potential therapeutic agent, the aim of this study was to characterise glucagon kinetics in mice and its regulation by the nutritional state. Methods: Anaesthetised C57BL/6 mice fed normal or high-fat diets, or fasted, were injected intravenously with glucagon (0.1, 0.3, 1.0, 10.0 or 20 μg/kg); blood samples were withdrawn before injection and 1, 3, 5, 10, 20 min thereafter for glucagon assay by RIA. Glucagon kinetics were described by two-compartment models using a population analysis. Results: The population mean and between-animal SD of glucagon clearance in the fed mice was 6.03±2.58 ml/min, with a rapid elimination half-life of 2.92±1.21 min. Fasted mice showed a slower glucagon clearance. The kinetics of glucagon in the fed and fasted group was linear across this large dose range. The mice fed a high-fat diet, however, showed non-linear kinetics with a faster terminal clearance of 20.4±5.45 ml/min (p<0.001) and a shorter elimination half-life of 1.59±0.606 (p<0.001) min relative to normal mice. Conclusions/interpretation: This first systematic dose-ranging study of glucagon kinetics produced several findings: (1) a linear two-compartment model describes glucagon in normal C57BL/6 mice; (2) fasting reduces the clearance of glucagon and (3) high-fat diet enhances the clearance of glucagon. These results may direct future studies on glucagon physiology and indicate that there are other mechanisms, not included in the current model, needed to fully explain glucagon's kinetics.
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