| 1. |
- Hägg, Daniel, 1974, et al.
(författare)
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Osteoblast-lineage cells regulate metabolism and fat mass
- 2023
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Ingår i: Current Opinion in Endocrine and Metabolic Research. - 2451-9650. ; 31
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Forskningsöversikt (refereegranskat)abstract
- As energy depots in many circumstances have been limited during evolution, it is necessary to prioritize how to manage energy resources. In this review we summarize data from the last 15 years indicating that osteoblast-lineage cells are regulators of whole-body energy metabolism and fat mass. We focus mainly on three factors, osteocalcin, lipocalin-2 and sclerostin, that are released by osteoblast-lineage cells and proposed to exert endocrine effects on metabolism. In addition, we present a hypothesis on why osteoblast-lineage cells during evolution have developed a function to regulate metabolism and fat mass. We propose that osteoblast-lineage cells through the osteocyte network in bone are sensors of gravitational forces induced by body mass and gravity on land-living species. By sensing the body weight, the osteoblastlineage cells may then feed-back this information on the whole-body nutritional status via osteoblast-derived endocrine factors or via the nervous system to regulate energy metabolism and fat mass.
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| 2. |
- Jansson, John-Olov, 1954, et al.
(författare)
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The dual hypothesis of homeostatic body weight regulation, including gravity-dependent and leptin-dependent actions.
- 2023
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Ingår i: Philosophical transactions of the Royal Society of London. Series B, Biological sciences. - 1471-2970. ; 378:1888
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Forskningsöversikt (refereegranskat)abstract
- Body weight is tightly regulated when outside the normal range. It has been proposed that there are individual-specific lower and upper intervention points for when the homeostatic regulation of body weight is initiated. The nature of the homeostatic mechanisms regulating body weight at the lower and upper ends of the body weight spectrum might differ. Previous studies demonstrate that leptin is the main regulator of body weight at the lower end of the body weight spectrum. We have proposed that land-living animals use gravity to regulate their body weight. We named this homeostatic system the gravitostat and proposed that there are two components of the gravitostat. First, an obvious mechanism involves increased energy consumption in relation to body weight when working against gravity on land. In addition, we propose that there exists a component, involving sensing of the body weight by osteocytes in the weight-bearing bones, resulting in a feedback regulation of energy metabolism and body weight. The gravity-dependent homeostatic regulation is mainly active in obese mice. We, herein, propose the dual hypothesis of body weight regulation, including gravity-dependent actions (= gravitostat) at the upper end and leptin-dependent actions at the lower end of the body weight spectrum. This article is part of a discussion meeting issue 'Causes of obesity: theories, conjectures and evidence (Part II)'.
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| 3. |
- Ohlsson, Claes, 1965, et al.
(författare)
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Increased weight loading reduces body weight and body fat in obese subjects – A proof of concept randomized clinical trial
- 2020
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Ingår i: EClinicalMedicine. - : Elsevier BV. - 2589-5370. ; 22
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Tidskriftsartikel (refereegranskat)abstract
- Background: Recently we provided evidence for a leptin-independent homeostatic regulation, the gravitostat, of body weight in rodents. The aim of the present translational proof of concept study was to test the gravitostat hypothesis in humans. Methods: We conducted a randomized controlled single center trial (ClinicalTrial.gov number, NCT03672903), to evaluate the efficacy of artificially increased weight loading on body weight in subjects with mild obesity (BMI 30–35 kg/m2). Subjects were either treated with a heavy (=high load; 11% of body weight) or light (=low load; 1% of body weight) weight vest for eight hours per day for three weeks. The primary outcome was change in body weight. Secondary outcomes included change in body fat mass and fat-free mass as measured using bioelectrical impedance analysis. Findings: In total 72 participants underwent randomization and 69 (36 high load and 33 low load) completed the study for the primary outcome. High load treatment resulted in a more pronounced relative body weight loss compared to low load treatment (mean difference -1.37%, 95% confidence interval (CI), -1.96 to -0.79; p = 1.5 × 10−5). High load treatment reduced fat mass (-4.04%, 95% CI, -6,53 to -1.55; p = 1.9 × 10−3) but not fat free mass (0.43%, 95% CI, -1.47 to 2.34; p = 0.65) compared to low load treatment. Interpretation: Increased weight loading reduces body weight and fat mass in obese subjects in a similar way as previously shown in obese rodents. These findings demonstrate that there is weight loading dependent homeostatic regulation of body weight, the gravitostat, also in humans. Funding: Funded by Jane and Dan Olsson (JADO) Foundation, the Torsten Söderberg Foundation, The Knut and Alice Wallenberg's Foundation and the Novo Nordisk Foundation. © 2020 The Author(s)
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| 4. |
- Bake, Tina, et al.
(författare)
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The gravitostat protects diet-induced obese rats against fat accumulation and weight gain
- 2021
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Ingår i: Journal of Neuroendocrinology. - : Wiley. - 0953-8194 .- 1365-2826. ; 33:8
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Tidskriftsartikel (refereegranskat)abstract
- The gravitostat is a novel homeostatic body weight-regulating mechanism, mostly studied in mice, and recently confirmed in obese humans. In the present study, we explored the effect of weight loading on metabolic outcomes, meal patterns and parameters linked to energy expenditure in both obese and lean rats. Diet-induced obese (DIO) and lean rats were implanted with capsules weighing either 15% of biological body weight (load) or empty capsules (1.3% of body weight; controls). Loading protected against fat accumulation more markedly in the DIO group. In line with this, the obesity-related impairment in insulin sensitivity was notably ameliorated in DIO rats upon loading, as revealed by the reduction in serum insulin levels and homeostatic model assessment for insulin resistance index scores. Although 24-hour caloric intake was reduced in both groups, this effect was greater in loaded DIO rats than in loaded lean peers. During days 10-16, after recovery from surgery, loading: (i) decreased meal size in both groups (only during the light phase in DIO rats) but this was compensated in lean rats by an increase in meal frequency; (ii) reduced dark phase locomotor activity only in lean rats; and (iii) reduced mean caloric efficiency in DIO rats. Muscle weight was unaffected by loading in either group. Dietary-obese rats are therefore more responsive than lean rats to loading.
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| 5. |
- Bygdell, Maria, et al.
(författare)
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Revisiting the critical weight hypothesis for regulation of pubertal timing in boys.
- 2021
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Ingår i: The American journal of clinical nutrition. - : Elsevier BV. - 1938-3207 .- 0002-9165. ; 113:1
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Tidskriftsartikel (refereegranskat)abstract
- Recent findings indicate that there is a body weight-sensing homeostatic regulation of body weight in postpubertal rodents and humans. It is possible that body weight sensing also might be involved in the regulation of pubertal timing. Although an early small study suggested that there is a critical body weight for pubertal timing in girls, most studies have focused on BMI and reported an inverse association between BMI and pubertal timing.In the present longitudinal well-powered cohort study, we revisited the critical weight hypothesis and tested if prepubertal body weight is a more robust inverse predictor of pubertal timing than prepubertal BMI in boys.We included men born during 1945-1961 (old cohort; n = 31,971) and men born during 1981-1996 (recent cohort; n = 1465) in the large BMI Epidemiology Study (BEST) Gothenburg (combined BEST cohort n = 33,436). Men with information on prepubertal body weight and BMI at 8 y of age and age at peak height velocity (PHV; an objective measure of pubertal timing) were included.Body weight explained more of the variance in age at PHV than BMI in both the old cohort and the recent cohort (combined cohort, body weight 6.3%, BMI 3.6%). Both body weight (β: -0.24 SD/SD increase in weight; 95% CI: -0.25, -0.23) and BMI (β: -0.18 SD/SD increase in BMI, 95% CI: -0.19, -0.17) were inversely associated with age at PHV but the association for body weight was significantly more pronounced than the association for BMI (P < 0.001).In conclusion, prepubertal body weight is a more robust inverse predictor of pubertal timing than prepubertal BMI in boys. We propose that body weight sensing constitutes a feedback mechanism to regulate pubertal timing.
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| 6. |
- Jansson, John-Olov, 1954, et al.
(författare)
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A Body Weight Sensor Regulates Prepubertal Growth via the Somatotropic Axis in Male Rats
- 2021
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Ingår i: Endocrinology. - : The Endocrine Society. - 0013-7227 .- 1945-7170. ; 162:6
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Tidskriftsartikel (refereegranskat)abstract
- In healthy conditions, prepubertal growth follows an individual specific growth channel. Growth hormone (GH) is undoubtedly the major regulator of growth. However, the homeostatic regulation to maintain the individual specific growth channel during growth is unclear. We recently hypothesized a body weight sensing homeostatic regulation of body weight during adulthood, the gravitostat. We now investigated if sensing of body weight also contributes to the strict homeostatic regulation to maintain the individual specific growth channel during prepubertal growth. To evaluate the effect of increased artificial loading on prepubertal growth, we implanted heavy (20% of body weight) or light (2% of the body weight) capsules into the abdomen of 26-day-old male rats. The body growth, as determined by change in biological body weight and growth of the long bones and the axial skeleton, was reduced in rats bearing a heavy load compared with light load. Removal of the increased load resulted in a catch-up growth and a normalization of body weight. Loading decreased hypothalamic growth hormone releasing hormone mRNA, liver insulin-like growth factor (IGF)-1 mRNA, and serum IGF-1, suggesting that the reduced body growth was caused by a negative feedback regulation on the somatotropic axis and this notion was supported by the fact that increased loading did not reduce body growth in GH-treated rats. Based on these data, we propose the gravitostat hypothesis for the regulation of prepubertal growth. This states that there is a homeostatic regulation to maintain the individual specific growth channel via body weight sensing, regulating the somatotropic axis and explaining catch-up growth.
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| 7. |
- Lantero Rodriguez, Marta, et al.
(författare)
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Testosterone reduces metabolic brown fat activity in male mice
- 2021
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Ingår i: Journal of Endocrinology. - : Bioscientifica. - 0022-0795 .- 1479-6805. ; 251:1, s. 83-96
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Tidskriftsartikel (refereegranskat)abstract
- Brown adipose tissue (BAT) burns substantial amounts of mainly lipids to produce heat. Some studies indicate that BAT activity and core body temperature are lower in males than females. Here we investigated the role of testosterone and its receptor (the androgen receptor; AR) in metabolic BAT activity in male mice. Castration, which renders mice testosterone deficient, slightly promoted the expression of thermogenic markers in BAT, decreased BAT lipid content, and increased basal lipolysis in isolated brown adipocytes. Further, castration increased the core body temperature. Triglyceride-derived fatty acid uptake, a proxy for metabolic BAT activity in vivo, was strongly increased in BAT from castrated mice ( 4.5-fold increase vs sham-castrated mice) and testosterone replacement reversed the castration-induced increase in metabolic BAT activity. BAT-specific AR deficiency did not mimic the castration effects in vivo and AR agonist treatment did not diminish the activity of cultured brown adipocytes in vitro, suggesting that androgens do not modulate BAT activity via a direct, AR-mediated pathway. In conclusion, testosterone is a negative regulator of metabolic BAT activity in male mice. Our findings provide new insight into the metabolic actions of testosterone.
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| 8. |
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| 9. |
- Svahn, Sara L, et al.
(författare)
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Spleen proteomics data from high fat diet fed mice
- 2020
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Ingår i: Data in Brief. - : Elsevier BV. - 2352-3409. ; 32
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Tidskriftsartikel (refereegranskat)abstract
- The composition of the diet affects many processes in the body, including body weight and endocrine system. We have previously shown that dietary fat also affects the immune system. Mice fed high fat diet rich in polyunsaturated fatty acids survive S. aureus infection to a much greater extent than mice fed high fat diet rich in saturated fatty acids. Here we present data regarding the dietary effects on protein expression in spleen from mice fed three different diets, I) low fat/chow diet (LFD, n = 4), II) high fat diet rich in saturated fatty acids (HFD-S, n = 4) and III) high fat diet rich in polyunsaturated fatty acids (HFD-P, n = 4). We performed mass spectrophotometry based quantitative proteomics analysis of isolated spleen by implementing the isobaric tags for relative and absolute quantification (iTRAQ) approach. Mass spectrometry data were analyzed using Proteome Discoverer 2.4 software using the search engine mascot against Mus musculus in SwissProt. 924 proteins are identified in all sets (n = 4) for different dietary effects taken for statistical analysis using Qlucore Omics Explorer software. Only 20 proteins were found to be differentially expressed with a cut-off value of false discovery rate < 0.1 (q-value) when comparing HFD-S and HFD-P but no differentially expressed proteins were found when LFD was compared with HFD-P or HFD-S. The identified proteins and statistical analysis comparing HFD-S and HFD-P diets are available as a supplementary file S1. We identified a subset of proteins that showed an inverse expression pattern between two high fat diets. These differentially expressed proteins were further classified by gene ontology for their role in biological processes and molecular functions. Mass spectrometry raw data are also available via ProteomeXchange with identifier PXD020365.
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| 10. |
- Zlatkovic, Jovana, et al.
(författare)
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Reduction of body weight by increased loading is associated with activation of norepinephrine neurones in the medial nucleus of the solitary tract.
- 2023
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Ingår i: Journal of neuroendocrinology. - 1365-2826. ; 35:12
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Tidskriftsartikel (refereegranskat)abstract
- We previously provided evidence supporting the existence of a novel leptin-independent body weight homeostat ("the gravitostat") that senses body weight and then initiates a homeostatic feed-back regulation of body weight. We, herein, hypothesize that this feed-back regulation involves a CNS mechanism. To identify populations of neurones of importance for the putative feed-back signal induced by increased loading, high-fat diet-fed rats or mice were implanted intraperitoneally or subcutaneously with capsules weighing ∼15% (Load) or ∼2.5% (Control) of body weight. At 3-5 days after implantation, neuronal activation was assessed in different parts of the brain/brainstem by immunohistochemical detection of FosB. Implantation of weighted capsules, both subcutaneous and intraperitoneal, induced FosB in specific neurones in the medial nucleus of the solitary tract (mNTS), known to integrate information about the metabolic status of the body. These neurones also expressed tyrosine hydroxylase (TH) and dopamine-beta-hydroxylase (DbH), a pattern typical of norepinephrine neurones. In functional studies, we specifically ablated norepinephrine neurones in mNTS, which attenuated the feed-back regulation of increased load on body weight and food intake. In conclusion, increased load appears to reduce body weight and food intake via activation of norepinephrine neurones in the mNTS.
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