| 161. |
- Nylen, C, et al.
(författare)
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IL6 and LIF mRNA expression in skeletal muscle is regulated by AMPK and the transcription factors NFYC, ZBTB14, and SP1
- 2018
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Ingår i: American journal of physiology. Endocrinology and metabolism. - : American Physiological Society. - 1522-1555 .- 0193-1849. ; 315:5, s. E995-E1004
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Tidskriftsartikel (refereegranskat)abstract
- Adenosine monophosphate-activated protein kinase (AMPK) controls glucose and lipid metabolism and modulates inflammatory responses to maintain metabolic and inflammatory homeostasis during low cellular energy levels. The AMPK activator 5-aminoimidazole-4-carboxamide-1-β-4-ribofuranoside (AICAR) interferes with inflammatory pathways in skeletal muscle, but the mechanisms are undefined. We hypothesized that AMPK activation reduces cytokine mRNA levels by blocking transcription through one or several transcription factors. Three skeletal muscle models were used to study AMPK effects on cytokine mRNA: human skeletal muscle strips obtained from healthy men incubated in vitro, primary human muscle cells, and rat L6 cells. In all three skeletal muscle systems, AICAR acutely reduced cytokine mRNA levels. In L6 myotubes treated with the transcriptional blocker actinomycin D, AICAR addition did not further reduce Il6 or leukemia inhibitory factor ( Lif) mRNA, suggesting that AICAR modulates cytokine expression through regulating transcription rather than mRNA stability. A cross-species bioinformatic approach identified novel transcription factors that may regulate LIF and IL6 mRNA. The involvement of these transcription factors was studied after targeted gene-silencing by siRNA. siRNA silencing of the transcription factors nuclear transcription factor Y subunit c ( Nfyc), specificity protein 1 ( Sp1), and zinc finger and BTB domain containing 14 ( Zbtb14), or AMPK α1/α2 subunits, increased constitutive levels of Il6 and Lif. Our results identify novel candidates in the regulation of skeletal muscle cytokine expression and identify AMPK, Nfyc, Sp1, and Zbtb14 as novel regulators of immunometabolic signals from skeletal muscle.
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| 162. |
- Nylen, C, et al.
(författare)
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Short-term low-calorie diet remodels skeletal muscle lipid profile and metabolic gene expression in obese adults
- 2019
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Ingår i: American journal of physiology. Endocrinology and metabolism. - : American Physiological Society. - 1522-1555 .- 0193-1849. ; 316:2, s. E178-E185
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Tidskriftsartikel (refereegranskat)abstract
- Diet intervention in obese adults is the first strategy to induce weight loss and improve insulin sensitivity. We hypothesized that improvements in insulin sensitivity after weight loss from a short-term dietary intervention tracks with alterations in expression of metabolic genes and abundance of specific lipid species. Eight obese, insulin-resistant, nondiabetic adults were recruited to participate in a 3-wk low-calorie diet intervention cohort study (1,000 kcal/day). Fasting blood samples and vastus lateralis skeletal muscle biopsies were obtained before and after the dietary intervention. Clinical chemistry and measures of insulin sensitivity were determined. Unbiased microarray gene expression and targeted lipidomic analysis of skeletal muscle was performed. Body weight was reduced, insulin sensitivity [measured by homeostatic model assessment of insulin resistance, (HOMA-IR)] was enhanced, and serum insulin concentration and blood lipid (triglyceride, cholesterol, LDL, and HDL) levels were improved after dietary intervention. Gene set enrichment analysis of skeletal muscle revealed that biosynthesis of unsaturated fatty acid was among the most enriched pathways identified after dietary intervention. mRNA expression of PDK4 and MLYCD increased, while SCD1 decreased in skeletal muscle after dietary intervention. Dietary intervention altered the intramuscular lipid profile of skeletal muscle, with changes in content of phosphatidylcholine and triglyceride species among the pronounced. Short-term diet intervention and weight loss in obese adults alters metabolic gene expression and reduces specific phosphatidylcholine and triglyceride species in skeletal muscle, concomitant with improvements in clinical outcomes and enhanced insulin sensitivity.
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| 163. |
- Nystrom, T, et al.
(författare)
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Effects of glucagon-like peptide-1 on endothelial function in type 2 diabetes patients with stable coronary artery disease
- 2004
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Ingår i: American Journal of Physiology: Endocrinology and Metabolism. - : American Physiological Society. - 1522-1555 .- 0193-1849. ; 287:6, s. 1209-1215
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Tidskriftsartikel (refereegranskat)abstract
- GLP-1 stimulates insulin secretion, suppresses glucagon secretion, delays gastric emptying, and inhibits small bowel motility, all actions contributing to the anti-diabetogenic peptide effect. Endothelial dysfunction is strongly associated with insulin resistance and type 2 diabetes mellitus and may cause the angiopathy typifying this debilitating disease. Therefore, interventions affecting both endothelial dysfunction and insulin resistance may prove useful in improving survival in type 2 diabetes patients. We investigated GLP-1's effect on endothelial function and insulin sensitivity (S-I) in two groups: 1) 12 type 2 diabetes patients with stable coronary artery disease and 2) 10 healthy subjects with normal endothelial function and S-I. Subjects underwent infusion of recombinant GLP-1 or saline in a random crossover study. Endothelial function was measured by postischemic FMD of brachial artery, using ultrasonography. S-I [in (10(-4) dl.kg(-1).min(-1))/(muU/ml)] was measured by hyperinsulinemic isoglycemic clamp technique. In type 2 diabetic subjects, GLP-1 infusion significantly increased relative changes in brachial artery diameter from baseline FMD(%) (3.1 +/- 0.6 vs. 6.6 +/- 1.0%, P < 0.05), with no significant effects on S-I (4.5 &PLUSMN; 0.8 vs. 5.2 &PLUSMN; 0.9, P = NS). In healthy subjects, GLP-1 infusion affected neither FMD(%) (11.9 &PLUSMN; 0.9 vs. 10.3 &PLUSMN; 1.0%, P = NS) nor S-I (14.8 &PLUSMN; 1.8 vs. 11.6 &PLUSMN; 2.0, P = NS). We conclude that GLP-1 improves endothelial dysfunction but not insulin resistance in type 2 diabetic patients with coronary heart disease. This beneficial vascular effect of GLP-1 adds yet another salutary property of the peptide useful in diabetes treatment.
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| 164. |
- Nystrom, T, et al.
(författare)
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Tetrahydrobiopterin increases insulin sensitivity in patients with type 2 diabetes and coronary heart disease
- 2004
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Ingår i: American journal of physiology. Endocrinology and metabolism. - : American Physiological Society. - 0193-1849 .- 1522-1555. ; 287:5, s. E919-E925
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Tidskriftsartikel (refereegranskat)abstract
- Tetrahydrobiopterin (BH4) is an essential cofactor of nitric oxide synthase that improves endothelial function in diabetics, smokers, and patients with hypercholesterolemia. Insulin resistance has been suggested as a contributing factor in the development of endothelial dysfunction via an abnormal pteridine metabolism. We hypothesized that BH4 would restore flow-mediated vasodilation (FMD, endothelial-dependent vasodilation), which may affect insulin resistance in type 2 diabetic patients. Thirty-two subjects (12 type 2 diabetic subjects, 10 matched nondiabetic subjects, and 10 healthy unmatched subjects) underwent infusion of BH4 or saline in a random crossover study. Insulin sensitivity index (SI) was measured by hyperinsulinemic isoglycemic clamp. FMD was measured using ultrasonography. BH4 significantly increased SI in the type 2 diabetics [3.6 ± 0.6 vs. 4.9 ± 0.7 × 10−4 dl·kg−1·min−1/(μU/ml), P < 0.05], while having no effects in nondiabetics [8.9 ± 1.1 vs. 9.0 ± 0.9 × 10−4 dl·kg−1·min−1/(μU/ml), P = 0.92] or in healthy subjects [17.5 ± 1.6 vs. 18 ± 1.8 × 10−4 dl·kg−1·min−1/(μU/ml), P = 0.87]. BH4 did not affect the relative changes in brachial artery diameter from baseline FMD (%) in type 2 diabetic subjects (2.3 ± 0.8 vs. 1.8 ± 1.0%, P = 0.42), nondiabetic subjects (5.3 ± 1.1 vs. 6.6 ± 0.9%, P = 0.32), or healthy subjects (11.9 ± 0.6 vs. 11.0 ± 1.0%, P = 0.48). In conclusion, BH4 significantly increases insulin sensitivity in type 2 diabetic patients without any discernible improvement in endothelial function.
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| 165. |
- Ohlsson, Claes, 1965, et al.
(författare)
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Increased adipose tissue aromatase activity improves insulin sensitivity and reduces adipose tissue inflammation in male mice.
- 2017
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Ingår i: American journal of physiology. Endocrinology and metabolism. - : American Physiological Society. - 1522-1555 .- 0193-1849. ; 313:4
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Tidskriftsartikel (refereegranskat)abstract
- Females are in general more insulin sensitive than males. To investigate if this is a direct effect of sex-steroids (SS) in white adipose tissue (WAT), we developed a male mouse model over expressing the aromatase enzyme, converting testosterone (T) to estradiol (E2), specifically in WAT (Ap2-arom mice). Adipose tissue E2 levels were increased while circulating SS levels were unaffected in male Ap2-arom mice. Importantly, male Ap2-arom mice were more insulin sensitive compared with WT mice and exhibited increased serum adiponectin levels and upregulated expression of Glut4 and Irs1 in WAT. The expression of markers of macrophages and immune cell infiltration was markedly decreased in WAT of male Ap2-arom mice. The adipogenesis was enhanced in male Ap2-arom mice, supported by elevated Pparg expression in WAT and enhanced differentiation of pre-adipocyte into mature adipocytes. In summary, increased adipose tissue aromatase activity reduces adipose tissue inflammation and improves insulin sensitivity in male mice. We propose that estrogen increases insulin sensitivity via a local effect in WAT on adiponectin expression, adipose tissue inflammation, and adipogenesis.
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| 166. |
- Ohlsson, Claes, 1965, et al.
(författare)
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Mild stimulatory effect of a probiotic mix on bone mass when treatment is initiated 1.5 weeks after ovariectomy in mice
- 2021
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Ingår i: American Journal of Physiology-Endocrinology and Metabolism. - : American Physiological Society. - 0193-1849 .- 1522-1555. ; 320:3
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Tidskriftsartikel (refereegranskat)abstract
- Studies in humans and rodents show that probiotic bacteria can protect from bone loss caused by sex steroid deficiency. We showed earlier that a mixture of three probiotic bacteria, Lacticaseibacillus paracasei DSM13434, Lactiplantibacillus plantarum DSM 15312, and DSM 15313 (L. mix), protects mice from ovariectomy (ovx)-induced bone loss when treatment was started 2 wk before sham and ovx surgery. In addition, the same probiotic treatment protected against lumbar spine bone loss in early postmenopausal women. In the present study, we wanted to evaluate the therapeutic potential of L. mix by starting treatment 1.5 wk after ovx when most of the rapid bone loss as a result of estrogen deficiency has already occurred. Treatment with L. mix for 5.5 wk increased the trabecular thickness but not the trabecular number in the proximal metaphyseal region of tibia compared with vehicle treatment. Cortical thickness and cortical area of the middiaphyseal part of the tibia were significantly decreased in ovx mice but not in L. mix-treated ovx mice. The bone-protective effects of L. mix in ovx mice were associated with a protection against ovx-induced reduction of the frequency of regulatory T-cells and of the expression of Tgfb in the bone marrow. In conclusion, the probiotic L. mix exerted a mild stimulatory effect on trabecular and cortical bone width when treatment is initiated 1.5 wk after ovariectomy in mice. This effect was associated with effects on bone-protecting regulatory T-cells. The results suggest that L. mix may exert beneficial effects on bone mass when treatment is started after ovariectomy. NEW & NOTEWORTHY The probiotic L. mix exerted a mild stimulatory effect on trabecular and cortical bone width when treatment is initiated 1.5 wk after ovariectomy in mice. This effect was associated with effects on bone-protecting regulatory T-cells. The results suggest that L. mix may exert beneficial effects on bone mass when treatment is started after ovariectomy.
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| 167. |
- Ohlsson, Claes, 1965, et al.
(författare)
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The effects of estradiol are modulated in a tissue-specific manner in mice with inducible inactivation of ERα after sexual maturation.
- 2020
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Ingår i: American journal of physiology. Endocrinology and metabolism. - : American Physiological Society. - 1522-1555 .- 0193-1849. ; 318:5, s. 646-654
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Tidskriftsartikel (refereegranskat)abstract
- Mouse models with lifelong inactivation of estrogen receptor α (ERα) show that ERα is the main mediator of estrogenic effects in bone, thymus, uterus, and fat. However, ERα inactivation early in life may cause developmental effects that confound the adult phenotypes. To address the specific role of adult ERα expression for estrogenic effects in bone and other non-skeletal tissues, we established a tamoxifen-inducible ERα-inactivated model by crossing CAG-Cre-ER and ERαflox/flox mice. Tamoxifen-induced ERα-inactivation after sexual maturation substantially reduced ERα mRNA levels in cortical bone, trabecular bone, thymus, uterus, gonadal fat, and hypothalamus, in CAG-Cre-ERαflox/flox (inducible ERαKO) compared to ERαflox/flox (control) mice. 17β-estradiol (E2) treatment increased trabecular bone volume fraction (BV/TV), cortical bone area and uterine weight, while it reduced thymus weight and fat mass in ovariectomized control mice. The estrogenic responses were substantially reduced in inducible ERαKO mice compared to control mice on BV/TV (-67%), uterine weight (-94%), thymus weight (-70%), and gonadal fat mass (-94%). In contrast, the estrogenic response on cortical bone area was unaffected in inducible ERαKO compared to control mice. In conclusion, using an inducible ERαKO model, not confounded by lack of ERa during development, we demonstrate that ERα expression in sexually mature female mice is required for normal E2 responses in most, but not all tissues. The finding that cortical, but not trabecular bone, responds normally to E2 treatment in inducible ERαKO mice strengthens the idea of cortical and trabecular bone being regulated by estrogen via different mechanisms.
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| 168. |
- Ohlsson, Claes, 1965, et al.
(författare)
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WNT16 overexpression partly protects against glucocorticoid-induced bone loss
- 2018
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Ingår i: American Journal of Physiology-Endocrinology and Metabolism. - : American Physiological Society. - 0193-1849 .- 1522-1555. ; 314:6
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Tidskriftsartikel (refereegranskat)abstract
- Therapeutic use of glucocorticoids (GCs) is a major cause of secondary osteoporosis, but the molecular mechanisms responsible for the deleterious effects of GCs in bone are only partially understood. WNT16 is a crucial physiological regulator of bone mass and fracture susceptibility, and we hypothesize that disturbed WNT16 activity might be involved in the deleterious effects of GC in bone. Twelve-week-old female Obl-Wnt16 mice (WNT16 expression driven by the rat procollagen type I alpha 1 promoter) and wild-type (WT) littermates were treated with prednisolone (7.6 mg.kg(-1).day(-1)) or vehicle for 4 wk. We first observed that GC treatment decreased the Wnt16 mRNA levels in bone of female mice (-56.4 +/- 6.1% compared with vehicle, P < 0.001). We next evaluated if WNT16 overexpression protects against GC-induced bone loss. Dual-energy X-ray absorptiometry analyses revealed that GC treatment decreased total body bone mineral density in WT mice (-3.9 +/- 1.2%, P = 0.028) but not in Obl-Wnt16 mice (+1.3 +/- 1.4%, nonsignificant). Microcomputed tomography analyses showed that GC treatment decreased trabecular bone volume fraction (BV/TV) of the femur in WT mice (P = 0.019) but not in Obl-Wnt16 mice. Serum levels of the bone formation marker procollagen type I N-terminal propeptide were substantially reduced by GC treatment in WT mice (-50.3 +/- 7.0%, P = 0.008) but not in Obl-Wnt16 mice (-3.8 +/- 21.2%, nonsignificant). However, the cortical bone thickness in femur was reduced by GC treatment in both WT mice and Obl-Wnt16 mice. In conclusion. GC treatment decreases Wnt16 mRNA levels in bone and WNT16 overexpression partly protects against GC-induced bone loss.
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| 169. |
- Olausson, Hanna, et al.
(författare)
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Postnatal oxytocin alleviates adverse effects in adult rat offspring caused by maternal malnutrition
- 2003
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Ingår i: American Journal of Physiology. Endocrinology and Metabolism. - : American Physiological Society. - 0193-1849 .- 1522-1555. ; 284:3, s. E475-E480
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Tidskriftsartikel (refereegranskat)abstract
- Repeated oxytocin administration to adult rats causes a long-term decrease of plasma levels of corticosterone and blood pressure and stimulates growth and fat retention. Maternal undernutrition increases blood pressure and plasma corticosterone in adult offspring. We hypothesized that oxytocin treatment early in life would alleviate adverse effects of intrauterine food restriction. Male pups from ad libitum-fed and food-restricted (fed 60% of ad libitum intake) dams were injected with oxytocin or saline in days 1–14 after birth. At 4 mo, blood pressure, plasma levels of corticosterone, and adiposity were assessed. Oxytocin treatment decreased blood pressure independently of nutrition, whereas the increased plasma levels of corticosterone were lowered to normal levels in food-restricted offspring. Blood pressure and adiposity were not affected by in utero food restriction, whereas birth and adult weight were. In conclusion, postnatal events may alleviate adverse effects caused by in utero food restriction. In contrast to more severe food restriction, a moderate general food restriction during gestation had no effect on blood pressure in the offspring.
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| 170. |
- Olsson, B, et al.
(författare)
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Bovine growth hormone-transgenic mice have major alterations in hepatic expression of metabolic genes
- 2003
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Ingår i: American Journal of Physiology: Endocrinology and Metabolism. - : American Physiological Society. - 1522-1555 .- 0193-1849. ; 285:3, s. 504-511
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Tidskriftsartikel (refereegranskat)abstract
- Transgenic mice overexpressing growth hormone (GH) have been extensively used to study the chronic effects of elevated serum levels of GH. GH is known to have many acute effects in the liver, but little is known about the chronic effects of GH overexpression on hepatic gene expression. Therefore, we used DNA microarray to compare gene expression in livers from bovine GH (bGH)-transgenic mice and littermates. Hepatic expression of peroxisome proliferator-activated receptor-alpha (PPARalpha) and genes involved in fatty acid activation, peroxisomal and mitochondrial beta-oxidation, and production of ketone bodies was decreased. In line with this expression profile, bGH-transgenic mice had a reduced ability to form ketone bodies in both the fed and fasted states. Although the bGH mice were hyperinsulinemic, the expression of sterol regulatory element-binding protein (SREBP)-1 and most lipogenic enzymes regulated by SREBP-1 was reduced, indicating that these mice are different from other insulin-resistant models with respect to expression of SREBP-1 and its downstream genes. This study also provides several candidate genes for the well-known association between elevated GH levels and cardiovascular disease, e.g., decreased expression of scavenger receptor class B type I, hepatic lipase, and serum paraoxonase and increased expression of serum amyloid A-3 protein. We conclude that bGH-transgenic mice display marked changes in hepatic genes coding for metabolic enzymes and suggest that GH directly or indirectly regulates many of these hepatic genes via decreased expression of PPARalpha and SREBP-1.
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