| 1. |
|
|
| 2. |
- García, Maria C, et al.
(författare)
-
Mature-onset obesity in interleukin-1 receptor I knockout mice.
- 2006
-
Ingår i: Diabetes. - : American Diabetes Association. - 0012-1797 .- 1939-327X. ; 55:5, s. 1205-13
-
Tidskriftsartikel (refereegranskat)abstract
- Interleukin-1 (IL-1) is a major mediator of inflammation that exerts its biological activities through the IL-1 type I receptor (IL-1RI). The body weights of IL-1RI(-/-) mice of both sexes started to deviate from those of wild-type mice at 5-6 months of age and were 20% higher at 9 months of age. Visceral and subcutaneous fat mass, measured by dual-energy X-ray absorptiometry and magnetic resonance imaging, was markedly (1.5- to 2.5-fold) increased. Lean body mass and crown-rump length were also slightly (11 and 5%, respectively) increased, as was serum IGF-I. Obese IL-1RI(-/-) mice were insulin resistant, as evidenced by hyperinsulinemia, decreased glucose tolerance, and insulin sensitivity. To elucidate the mechanisms for the development of obesity, young pre-obese IL-1RI(-/-) mice were investigated. They showed decreased suppression of body weight and food intake in response to systemic leptin treatment. The decreased leptin responsiveness was even more pronounced in older obese animals. Moreover, spontaneous locomotor activity and fat utilization, as measured by respiratory quotient, were decreased in pre-obese IL-1RI(-/-) mice. In conclusion, lack of IL-1RI-mediated biological activity causes mature-onset obesity. This obese phenotype is preceded by decreased leptin sensitivity, fat utilization, and locomotor activity.
|
|
| 3. |
- Sjögren, Klara, 1970, et al.
(författare)
-
Liver-derived insulin-like growth factor I (IGF-I) is the principal source of IGF-I in blood but is not required for postnatal body growth in mice.
- 1999
-
Ingår i: Proceedings of the National Academy of Sciences of the United States of America. - 0027-8424. ; 96:12, s. 7088-92
-
Tidskriftsartikel (refereegranskat)abstract
- The body growth of animals is regulated by growth hormone and IGF-I. The classical theory of this regulation is that most IGF-I in the blood originates in the liver and that body growth is controlled by the concentration of IGF-I in the blood. We have abolished IGF-I production in the livers of mice by using the Cre/loxP recombination system. These mice demonstrated complete inactivation of the IGF-I gene in the hepatocytes. Although the liver accounts for less than 5% of body mass, the concentration of IGF-I in the serum was reduced by 75%. This finding confirms that the liver is the principal source of IGF-I in the blood. However, the reduction in serum IGF-I concentration had no discernible effect on postnatal body growth. We conclude that postnatal body growth is preserved despite complete absence of IGF-I production by the hepatocytes.
|
|
| 4. |
- Andersson, Niklas, 1970, et al.
(författare)
-
A variant near the interleukin-6 gene is associated with fat mass in Caucasian men
- 2010
-
Ingår i: International Journal of Obesity. - : Springer Science and Business Media LLC. - 0307-0565 .- 1476-5497. ; 34:6, s. 1011-9
-
Tidskriftsartikel (refereegranskat)abstract
- CONTEXT: Regulation of fat mass appears to be associated with immune functions. Studies of knockout mice show that endogenous interleukin (IL)-6 can suppress mature-onset obesity. OBJECTIVE: To systematically investigate associations of single nucleotide polymorphisms (SNPs) near the IL-6 (IL6) and IL-6 receptor (IL6R) genes with body fat mass, in support for our hypothesis that variants of these genes can be associated with obesity. DESIGN AND STUDY SUBJECTS: The Gothenburg Osteoporosis and Obesity Determinants (GOOD) study is a population-based cross-sectional study of 18- to 20-year-old men (n=1049), from the Gothenburg area (Sweden). Major findings were confirmed in two additional cohorts consisting of elderly men from the Osteoporotic Fractures in Men (MrOS) Sweden (n=2851) and MrOS US (n=5611) multicenter population-based studies. MAIN OUTCOME: The genotype distributions and their association with fat mass in different compartments, measured with dual-energy X-ray absorptiometry. RESULTS: Out of 18 evaluated tag SNPs near the IL6 and IL6R genes, a recently identified SNP rs10242595 G/A (minor allele frequency=29%) 3' of the IL6 gene was negatively associated with the primary outcome total body fat mass (effect size -0.11 standard deviation (s.d.) units per A allele, P=0.02). This negative association with fat mass was also confirmed in the combined MrOS Sweden and MrOS US cohorts (effect size -0.05 s.d. units per A allele, P=0.002). When all three cohorts were combined (n=8927, Caucasian subjects), rs10242595(*)A showed a negative association with total body fat mass (effect size -0.05 s.d. units per A allele, P<0.0002). Furthermore, the rs10242595(*)A was associated with low body mass index (effect size -0.03, P<0.001) and smaller regional fat masses. None of the other SNPs investigated in the GOOD study were reproducibly associated with body fat. CONCLUSIONS: The IL6 gene polymorphism rs10242595(*)A is associated with decreased fat mass in three combined cohorts of 8927 Caucasian men.
|
|
| 5. |
- Andersson, Niklas, 1970, et al.
(författare)
-
Investigation of central versus peripheral effects of estradiol in ovariectomized mice
- 2005
-
Ingår i: J Endocrinol. - : Bioscientifica. - 0022-0795 .- 1479-6805. ; 187:2, s. 303-9
-
Tidskriftsartikel (refereegranskat)abstract
- It is generally believed that estrogens exert their bone sparing effects directly on the cells within the bone compartment. The aim of the present study was to investigate if central mechanisms might be involved in the bone sparing effect of estrogens. The dose-response of central (i.c.v) 17beta-estradiol (E2) administration was compared with that of peripheral (s.c.) administration in ovariectomized (ovx) mice. The dose-response curves for central and peripheral E2 administration did not differ for any of the studied estrogen-responsive tissues, indicating that these effects were mainly peripheral. In addition, ovx mice were treated with E2 and/or the peripheral estrogen receptor antagonist ICI 182,780. ICI 182,780 attenuated most of the estrogenic response regarding uterus weight, retroperitoneal fat weight, cortical BMC and trabecular bone mineral content (P<0.05). These findings support the notion that the primary target tissue that mediates the effect of E2 on bone is peripheral and not central.
|
|
| 6. |
- Andersson, Niklas, 1970, et al.
(författare)
-
Variants of the interleukin-1 receptor antagonist gene are associated with fat mass in men
- 2009
-
Ingår i: International Journal of Obesity. - : Springer Science and Business Media LLC. - 0307-0565 .- 1476-5497. ; 33:5, s. 525-533
-
Tidskriftsartikel (refereegranskat)abstract
- Context: Immune functions seem to have connections to variations in body fat mass. Studies of knockout mice indicate that endogenous interleukin (IL)-1 can suppress mature-onset obesity. Objective: To systematically investigate our hypotheses that single- nucleotide polymorphisms (SNPs) and/or haplotypes variants in the IL-1 gene system are associated with fat mass. Subjects: The Gothenburg osteoporosis and obesity determinants (GOOD) study is a population-based cross-sectional study of 18-20 year-old men (n = 1068), from Gothenburg, Sweden. Major findings were confirmed in elderly men (n = 3014) from the Swedish part of the osteoporotic fractures in men (MrOS) multicenter population-based study. Main Outcome Measure: The genotype distributions and their association with body fat mass in different compartments, measured with dual-energy X-ray absorptiometry (DXA). Results: Out of 15 investigated SNPs in the IL-1 receptor antagonist (IL1RN) gene, a recently identified 30 untranslated region C4T (rs4252041, minor allele frequency 4%) SNP was associated with the primary outcome total fat mass (P = 0.003) and regional fat masses, but not with lean body mass or serum IL-1 receptor 1 (IL1RN) levels. This SNP was also associated with body fat when correcting the earlier reported IL1RN_2018 T4C (rs419598) SNP (in linkage disequilibrium with a well-studied variable number tandem repeat of 86 bp). The association between rs4252041 SNP and body fat was confirmed in the older MrOS population (P = 0.03). The rs4252041 SNP was part of three haplotypes consisting of five adjacent SNPs that were identified by a sliding window approach. These haplotypes had a highly significant global association with total body fat (P < 0.001). None of the other investigated members of the IL-1 gene family displayed any SNPs that have not been described previously to be significantly associated with body fat. Conclusions: The IL1RN gene, shown to enhance obesity by suppressing IL-1 effects in experimental animals, have no previously described gene polymorphisms and haplotypes that are associated with fat, but not lean mass in two populations of men. International Journal of Obesity (2009) 33, 525-533; doi: 10.1038/ijo.2009.47; published online 17 March 2009
|
|
| 7. |
- Colldén, Hannah, et al.
(författare)
-
The gut microbiota is a major regulator of androgen metabolism in intestinal contents.
- 2019
-
Ingår i: American journal of physiology. Endocrinology and metabolism. - 1522-1555. ; 317:6, s. E1182-E1192
-
Tidskriftsartikel (refereegranskat)abstract
- Androgens exert important effects both in androgen-responsive tissues and in the intestinal tract. To determine the impact of the gut microbiota (GM) on intestinal androgen metabolism, we measured unconjugated (free) and glucuronidated androgen levels in intestinal contents from the small intestine, with a low bacterial density, and from cecum and colon, with a high bacterial density. Using a specific, sensitive gas chromatography-tandem mass spectrometry method, we detected high levels of glucuronidated testosterone (T) and dihydrotestosterone (DHT) in small intestinal content of mice of both sexes, whereas in the distal intestine we observed remarkably high levels of free DHT, exceeding serum levels by >20-fold. Similarly, in young adult men high levels of unconjugated DHT, >70-fold higher than in serum, were detected in feces. In contrast to mice with a normal GM composition, germ-free mice had high levels of glucuronidated T and DHT, but very low free DHT levels, in the distal intestine. These findings demonstrate that the GM is involved in intestinal metabolism and deglucuronidation of DHT and T, resulting in extremely high free levels of the most potent androgen, DHT, in the colonic content of young and healthy mice and men.
|
|
| 8. |
- Eriksson, Anna-Lena, 1971, et al.
(författare)
-
SHBG gene promoter polymorphisms in men are associated with serum sex hormone-binding globulin, androgen and androgen metabolite levels, and hip bone mineral density.
- 2006
-
Ingår i: The Journal of clinical endocrinology and metabolism. - : The Endocrine Society. - 0021-972X .- 1945-7197. ; 91:12, s. 5029-37
-
Tidskriftsartikel (refereegranskat)abstract
- CONTEXT: SHBG regulates free sex steroid levels, which in turn regulate skeletal homeostasis. Twin studies have demonstrated that genetic factors largely account for interindividual variation in SHBG levels. Glucuronidated androgen metabolites have been proposed as markers of androgenic activity. OBJECTIVE: Our objective was to investigate whether polymorphisms in the SHBG gene promoter [(TAAAA)(n) microsatellite and rs1799941 single-nucleotide polymorphism] are associated with serum levels of SHBG, sex steroids, or bone mineral density (BMD) in men. DESIGN AND STUDY SUBJECTS: We conducted a population-based study of two cohorts of Swedish men: elderly men (MrOS Sweden; n congruent with 3000; average age, 75.4 yr) and young adult men (GOOD study; n = 1068; average age, 18.9 yr). MAIN OUTCOME MEASURES: We measured serum levels of SHBG, testosterone, estradiol, dihydrotestosterone, 5alpha-androstane-3alpha,17beta-diol glucuronides, androsterone glucuronide, and BMD determined by dual-energy x-ray absorptiometry. RESULTS: In both cohorts, (TAAAA)(n) and rs1799941 genotypes were associated with serum levels of SHBG (P < 0.001), dihydrotestosterone (P < 0.05), and 5alpha-androstane-3alpha,17beta-diol glucuronides (P < 0.05). In the elderly men, they were also associated with testosterone and BMD at all hip bone sites. The genotype associated with high levels of SHBG was also associated with high BMD. Interestingly, male mice overexpressing human SHBG had increased cortical bone mineral content in the femur, suggesting that elevated SHBG levels may cause increased bone mass. CONCLUSIONS: Our findings demonstrate that polymorphisms in the SHBG promoter predict serum levels of SHBG, androgens, and glucuronidated androgen metabolites, and hip BMD in men.
|
|
| 9. |
- Graff, M., et al.
(författare)
-
Genome-wide physical activity interactions in adiposity. A meta-analysis of 200,452 adults
- 2017
-
Ingår i: PLoS Genet. - : Public Library of Science (PLoS). - 1553-7404 .- 1553-7390. ; 13:4
-
Tidskriftsartikel (refereegranskat)abstract
- Physical activity (PA) may modify the genetic effects that give rise to increased risk of obesity. To identify adiposity loci whose effects are modified by PA, we performed genome-wide interaction meta-analyses of BMI and BMI-adjusted waist circumference and waist-hip ratio from up to 200,452 adults of European (n = 180,423) or other ancestry (n = 20,029). We standardized PA by categorizing it into a dichotomous variable where, on average, 23% of participants were categorized as inactive and 77% as physically active. While we replicate the interaction with PA for the strongest known obesity-risk locus in the FTO gene, of which the effect is attenuated by similar to 30% in physically active individuals compared to inactive individuals, we do not identify additional loci that are sensitive to PA. In additional genome-wide meta-analyses adjusting for PA and interaction with PA, we identify 11 novel adiposity loci, suggesting that accounting for PA or other environmental factors that contribute to variation in adiposity may facilitate gene discovery.
|
|
| 10. |
- Lorentzon, Mattias, 1970, et al.
(författare)
-
Free testosterone is a positive, whereas free estradiol is a negative, predictor of cortical bone size in young Swedish men: the GOOD study.
- 2005
-
Ingår i: Journal of bone and mineral research : the official journal of the American Society for Bone and Mineral Research. - 0884-0431. ; 20:8, s. 1334-41
-
Tidskriftsartikel (refereegranskat)abstract
- In this study, we evaluated the predictive roles of sex steroids for skeletal parameters in young men (n = 1068) at the age of peak bone mass. Serum free estradiol was a negative predictor, whereas free testosterone and SHBG were positive predictors of cortical bone size. INTRODUCTION: Previous studies have shown that free estradiol in serum is an independent predictor of areal BMD (aBMD) in elderly men. The aim of this study was to determine whether sex steroids are predictors of volumetric BMD (vBMD) and/or size of the trabecular and cortical bone compartments in young men at the age of peak bone mass. MATERIALS AND METHODS: The Gothenburg Osteoporosis and Obesity Determinants (GOOD) study consists of 1068 men, 18.9 +/- 0.6 years of age. Serum levels of testosterone, estradiol, and sex hormone binding globulin (SHBG) were measured, and free levels of testosterone and estradiol were calculated. The size of the cortical bone and the cortical and trabecular vBMDs were measured by pQCT. RESULTS: Regression models including age, height, weight, free estradiol, and free testosterone showed that free estradiol was an independent negative predictor of cortical cross-sectional area (tibia beta = -0.111, p < 0.001; radius beta = -0.125, p < 0.001), periosteal circumference, and endosteal circumference, whereas it was a positive independent predictor of cortical vBMD (tibia beta = 0.100, p < 0.003; radius beta = 0.115, p = 0.001) in both the tibia and radius. Free testosterone was an independent positive predictor of cortical cross-sectional area (tibia beta = 0.071, p = 0.013; radius beta = 0.064, p = 0.039), periosteal circumference, and endosteal circumference in both the tibia and radius. Neither cortical nor trabecular vBMD was associated with free testosterone. SHBG was an independent positive predictor of parameters reflecting the size of the cortical bone, including cross-sectional area (beta = 0.078, p = 0.009), periosteal circumference, and endosteal circumference. CONCLUSIONS: Free estradiol is a negative, whereas free testosterone is a positive, predictor of cortical bone size in young men at the age of peak bone mass. These findings support the notion that estrogens reduce, whereas androgens increase, cortical bone size, resulting in the well-known sexual dimorphism of cortical bone geometry.
|
|
