Direct effects of sex steroid hormones on adipose tissues and obesity

Sex hormones differentially influence voluntary running activity, food intake and body weight in aging female and male rats

The aim of this study was to examine the longer-term effects of reduced gonadal hormones on food intake, food efficiency, voluntary running activity and body weight in mature male and female rats, compared to age-matched controls. We hypothesized that hormonal effects would differ for rats that were not rapidly growing and our results are consistent with this hypothesis. 6-8 month male and female rats were divided into four groups: Female and male control groups and a female and male experimental group. Control groups were intact for 46 weeks. Experimental groups were intact during Phase I (16 weeks), ovariectomized or orchidectomized during Phase II (20 weeks), and received estrogen or testosterone hormone replacement therapy (HRT) during the final Phase III (10 weeks). Food intake and running distance were monitored daily and body weight was recorded weekly for 46 weeks. Contrary to findings for young and growing animals, we did not observe a (1) stabilization of food intake in female rats following OVX, (2) loss of body weight with ORX in males, or (3) complete restoration of running activity in ORX males given testosterone, compared to females given estrogen. Feeding efficiency was not affected by aging in females or males. Loss of estrogen increased energy intake whereas reduced testosterone in males resulted in a negative energy balance. Findings suggest variable hormonal effects for aging male/female rats.

Oral dehydroepiandrosterone replacement in older adults: effects on central adiposity, glucose metabolism and blood lipids

OBJECTIVE

To determine the effects of dehydroepiandrosterone (DHEA) therapy on changes in central adiposity, insulin action and blood lipids. Many of the actions of DHEA in humans are thought to be mediated through its conversion to sex hormones, which are modulators of adiposity, muscularity and insulin sensitivity. The effects of DHEA replacement on regional tissue composition, glucose metabolism and blood lipid profile in older adults have been inconsistent.

DESIGN

A randomized, double-blinded, placebo-controlled trial. The intervention was oral DHEA 50 mg/day or placebo for 12 months.

PARTICIPANTS

Fifty-eighty women and 61 men, aged 60-88 years, with low serum DHEA sulphate (DHEAS) levels at study entry.

MEASUREMENTS

Computed tomography measures of abdominal fat areas, thigh muscle and fat areas, DXA-derived trunk fat mass, serum glucose and insulin responses to an oral glucose challenge, and fasted serum total cholesterol, HDL-cholesterol, LDL-cholesterol and triglycerides were assessed before and after the intervention.

RESULTS

There were no significant (P > 0·05) differences between the DHEA and placebo groups in the changes in regional tissue composition or glucose metabolism. HDL-cholesterol (P = 0·01) and fasted triglycerides (P = 0·02) decreased in women and men taking DHEA.

CONCLUSION

Restoring serum DHEAS levels in older adults to young adult levels for 1 year does not appear to reduce central adiposity or improve insulin action. The benefit of DHEA on decreasing serum triglycerides must be weighed against the HDL-lowering effect.

The in utero programming effect of increased maternal androgens and a direct fetal intervention on liver and metabolic function in adult sheep

Epigenetic changes in response to external stimuli are fast emerging as common underlying causes for the pre-disposition to adult disease. Prenatal androgenization is one such model that results in reproductive and metabolic features that are present in conditions such as polycystic ovary syndrome (PCOS). We examined the effect of prenatal androgens on liver function and metabolism of adult sheep. As non-alcoholic fatty liver disease is increased in PCOS we hypothesized that this, and other important liver pathways including metabolic function, insulin–like growth factor (IGF) and steroid receptivity, would be affected. Pregnant ewes received vehicle control (C; n = 5) or testosterone propionate (TP; n = 9) twice weekly (100 mg; i.m) from d62–102 (gestation 147 days). In a novel treatment paradigm, a second cohort received a direct C (n = 4) or TP (20 mg; n = 7) fetal injection at d62 and d82. In adults, maternal TP exposure resulted in increased insulin secretion to glucose load (P<0.05) and the histological presence of fatty liver (P<0.05) independent of central obesity. Additionally, hepatic androgen receptor (AR; P<0.05), glucocorticoid receptor (GR; P<0.05), UDP- glucose ceramide glucosyltransferase (UGCG; P<0.05) and IGF1 (P<0.01) expression were upregulated. The direct fetal intervention (C and TP) led to early fatty liver changes in all animals without differential changes in insulin secretion. Furthermore, hepatic phosphoenolpyruvate carboxykinase (PEPCK) was up-regulated in the fetal controls (P<0.05) and this was opposed by fetal TP (P<0.05). Hepatic estrogen receptor (ERα; P<0.05) and mitogen activated protein kinase kinase 4 (MAP2K4; P<0.05) were increased following fetal TP exposure. Adult liver metabolism and signaling can be altered by early exposure to sex steroids implicating epigenetic regulation of metabolic disturbances that are common in PCOS.

NAFLD, Estrogens, and Physical Exercise: The Animal Model

One segment of the population that is particularly inclined to liver fat accumulation is postmenopausal women. Although nonalcoholic hepatic steatosis is more common in men than in women, after menopause there is a reversal in gender distribution. At the present time, weight loss and exercise are regarded as first line treatments for NAFLD in postmenopausal women, as it is the case for the management of metabolic syndrome. In recent years, there has been substantial evidence coming mostly from the use of the animal model, that indeed estrogens withdrawal is associated with modifications of molecular markers favouring the activity of metabolic pathways ultimately leading to liver fat accumulation. In addition, the use of the animal model has provided physiological and molecular evidence that exercise training provides estrogens-like protective effects on liver fat accumulation and its consequences. The purpose of the present paper is to present information relative to the development of a state of NAFLD resulting from the absence of estrogens and the role of exercise training, emphasizing on the contribution of the animal model on these issues.

NAFLD, Estrogens, and Physical Exercise: The Animal Model

One segment of the population that is particularly inclined to liver fat accumulation is postmenopausal women. Although nonalcoholic hepatic steatosis is more common in men than in women, after menopause there is a reversal in gender distribution. At the present time, weight loss and exercise are regarded as first line treatments for NAFLD in postmenopausal women, as it is the case for the management of metabolic syndrome. In recent years, there has been substantial evidence coming mostly from the use of the animal model, that indeed estrogens withdrawal is associated with modifications of molecular markers favouring the activity of metabolic pathways ultimately leading to liver fat accumulation. In addition, the use of the animal model has provided physiological and molecular evidence that exercise training provides estrogens-like protective effects on liver fat accumulation and its consequences. The purpose of the present paper is to present information relative to the development of a state of NAFLD resulting from the absence of estrogens and the role of exercise training, emphasizing on the contribution of the animal model on these issues.

The evolutionary origin and significance of menopause

Contemporary women have long life expectancy (81 y, United States), especially relative to the age at menopause (51 y, United States). Menopause is a consequence of reproductive aging and follicular depletion (ovarian failure), yielding very low circulating estrogen serum concentrations and biologically disadvantageous metabolic alterations. Stated in terms of antagonistic pleiotropy, the ongoing hypoestrogenic endocrine environment, beneficial during lactation, results in acceleration of several age-related illnesses after menopause (ie, late postmenopausal osteoporosis, cardiovascular disease, and cognitive decline). Specifically, the similar hypoestrogenic hormonal milieu present during postpartum lactation provides biologic advantages (fitness) to both mother and newborn. These precepts of evolutionary medicine encourage a reassessment of hormone therapy, and on the basis of data presented the authors propose additional opportunities for disease prevention and morbidity reduction in postmenopausal women.

PPARγ: a molecular link between systemic metabolic disease and benign prostate hyperplasia

The emergent epidemic of metabolic syndrome and its complex list of sequelae mandate a more thorough understanding of benign prostatic hyperplasia and lower urinary tract symptoms (BPH/LUTS) in the context of systemic metabolic disease. Here we discuss the nature and origins of BPH, examine its role as a component of LUTS and review retrospective clinical studies that have drawn associations between BPH/LUTS and type II diabetes, inflammation and dyslipidemia. PPARγ signaling, which sits at the nexus of systemic metabolic disease and BPH/LUTS through its regulation of inflammation and insulin resistance, is proposed as a candidate for molecular manipulation in regard to BPH/LUTS. Finally, we introduce new cell and animal models that are being used to study the consequences of obesity, diabetes and inflammation on benign prostatic growth.

Sex differences in energy metabolism need to be considered with lifestyle modifications in humans

Women have a higher proportion of body fat compared to men. However, women consume fewer kilojoules per kilogram lean mass and burn fat more preferentially during exercise compared with men. During gestation, women store even greater amounts of fat that cannot be solely attributed to increased energy intake. These observations suggest that the relationship between kilojoules consumed and kilojoules utilised is different in men and women. The reason for these sex differences in energy metabolism is not known; however, it may relate to sex steroids, differences in insulin resistance, or metabolic effects of other hormones such as leptin. When considering lifestyle modifications, sex differences in energy metabolism should be considered. Moreover, elucidating the regulatory role of hormones in energy homeostasis is important for understanding the pathogenesis of obesity and perhaps in the future may lead to ways to reduce body fat with less energy restriction.

Acylation stimulating protein: a female lipogenic factor?

Acylation stimulating protein (ASP) is a potent lipogenic factor produced from adipocytes. Plasma ASP levels were shown to increase in obesity, diabetes mellitus type II and dyslipidemia, and decrease after weight loss and fasting. Growing evidence suggests that ASP may significantly contribute to subcutaneous fat storage in females. In vitro, ASP stimulated triglyceride synthesis to a larger extent in subcutaneous compared with omental adipocytes. The ASP receptor binding affinity to plasma membranes prepared from adipose tissue showed higher binding affinity to plasma membranes from female adipose tissue compared with male adipose tissue, and was more pronounced to subcutaneous compared with omental plasma membranes. Human studies demonstrated that postprandial triglyceride clearance predicted by ASP levels was more efficient in women than in men. In mice, postprandial triglyceride clearance, with intraperitoneal ASP administration, was faster in females compared with males. The ASP deficient mice were resistant to weight gain and had reduced fat mass that was more pronounced in females. Recent findings in humans and mice point to a significant association between progesterone and ASP variations in females. In this review, we highlight findings, to date, linking ASP to physiological and hormonal alterations that may contribute to subcutaneous fat distribution typical to females.

The glucocorticoid contribution to obesity

Obesity is fast becoming the scourge of our time. It is one of the biggest causes of death and disease in the industrialized world, and affects as many as 32% of adults and 17% of children in the USA, considered one of the world's fattest nations. It can also cost countries billions of dollars per annum in direct and indirect care, latest estimates putting the USA bill for obesity-related costs at $147 billion in 2008. It is becoming clear that the pathophysiology of obesity is vastly more complicated than the simple equation of energy in minus energy out. A combination of genetics, sex, perinatal environment and life-style factors can influence diet and energy metabolism. In this regard, psychological stress can have significant long-term impact upon the propensity to gain and maintain weight. In this review, we will discuss the ability of psychological stress and ultimately glucocorticoids (GCs) to alter appetite regulation and metabolism. We will specifically focus on (i) GC regulation of appetite and adiposity, (ii) the apparent sexual dimorphism in stress effects on obesity and (iii) the ability of early life stress to programme obesity in the long term.

Impact of sex hormone metabolism on the vascular effects of menopausal hormone therapy in cardiovascular disease

Epidemiological studies have shown that cardiovascular disease (CVD) is less common in pre-menopausal women (Pre-MW) compared to men of the same age or post-menopausal women (Post-MW), suggesting cardiovascular benefits of estrogen. Estrogen receptors (ERs) have been identified in the vasculature, and experimental studies have demonstrated vasodilator effects of estrogen/ER on the endothelium, vascular smooth muscle (VSM) and extracellular matrix. Several natural and synthetic estrogenic preparations have been developed for relief of menopausal vasomotor symptoms. However, whether menopausal hormone therapy (MHT) is beneficial in postmenopausal CVD remains controversial. Despite reports of vascular benefits of MHT from observational and experimental studies, randomized clinical trials (RCTs), such as the Heart and Estrogen/progestin Replacement Study (HERS) and the Women's Health Initiative (WHI), have suggested that, contrary to expectations, MHT may increase the risk of CVD. These discrepancies could be due to agerelated changes in sex hormone synthesis and metabolism, which would influence the effective dose of MHT and the sex hormone environment in Post-MW. Age-related changes in the vascular ER subtype, structure, expression, distribution, and post-ER signaling pathways in the endothelium and VSM, along with factors related to the design of RCTs, preexisting CVD condition, and structural changes in the blood vessels architecture have also been suggested as possible causes of MHT failure in CVD. Careful examination of these factors should help in identifying the causes of the changes in the vascular effects of estrogen with age. The sex hormone metabolic pathways, the active versus inactive estrogen metabolites, and their effects on vascular function, the mitochondria, the inflammatory process and angiogenesis should be further examined. Also, the genomic and non-genomic effects of estrogenic compounds should be viewed as integrated rather than discrete responses. The complex interactions between these factors highlight the importance of careful design of MHT RCTs, and the need of a more customized approach for each individual patient in order to enhance the vascular benefits of MHT in postmenopausal CVD.

Diet-induced obesity in rats leads to a decrease in sperm motility

BACKGROUND

Obesity is rapidly becoming a worldwide epidemic that affects children and adults. Some studies have shown a relationship between obesity and infertility, but until now it remains controversial. Thus, the aim of the present study was to investigate the effect of high-fat diet-induced obesity on male reproductive parameters.

METHODS

In a first experiment, male Wistar rats were fed a high-fat diet (HFD) or standard chow (SD) for 15, 30 or 45 weeks, after which they were evaluated by adiposity index, serum leptin levels, reproductive organ weights and sperm counts. In a second experiment, rats received HFD or SD only for 15 weeks, long enough to cause obesity. Sexual hormones and sexual behavior were evaluated in these animals, as well as fertility after natural mating. Another group of rats was submitted to motility analysis and fertility evaluation after in utero insemination.

RESULTS

After 15, 30 or 45 weeks, HFD-fed animals presented significant increases in obesity index and serum leptin levels. Reproductive organ weights and sperm counts in the testis and epididymis were similar between the two groups at all timepoints studied. Sexual behavior was not altered by the diet regimen, and HFD fertility after natural mating was also similar to SD-fed animals. Intergroup testosterone levels were also comparable, but estradiol levels were increased in HFD rats. Furthermore, sperm quality was reduced in HFD animals as evidenced by their decreased percentage of sperm with progressive movement. This altered motility parameter was followed by a trend toward reduction in fertility potential after artificial in utero insemination.

CONCLUSIONS

The results reported herein showed that obesity can affect sperm quality, by reducing sperm motility, without affecting other sperm parameters. The low sperm quality caused a slight reduction in fertility potential, showing that obesity may lead to impairment in male fertility.

Sex steroids influence glucose oxidation through modulation of insulin receptor expression and IRS-1 serine phosphorylation in target tissues of adult male rat

Skeletal muscle, liver, and adipose tissue are major insulin responsive target organs that also express androgen receptor. Testosterone (T) plays a role in maintaining normal insulin sensitivity in men but its effects on insulin target tissues are not fully understood. Our previous study showed that orchidectomy impairs glucose oxidation through decreased insulin receptor (IR) mRNA expression in skeletal muscles, liver, and adipose tissue of male rat. Furthermore, T replacement restored IR mRNA expression in skeletal muscles and liver, but did not have any effect in adipose tissue. In the present study, orchidectomy decreased IR mRNA and protein levels in muscle, liver, and adipose tissue. Treatment with a combination of T plus estradiol (E) was necessary to restore the IR mRNA and protein to control levels in adipose tissue. T or E treatment alone had no effect on IR mRNA levels in adipose tissue. T alone also had no effect on the IR protein, whereas E alone had a stimulatory effect. In comparison, in muscle and liver, T or T plus E restored the IR mRNA and protein to control levels. In muscle and liver, E alone had no effect on IR mRNA expression but restored the IR protein. In addition, orchidectomy was seen to have a stimulatory effect on IRS-1 Serine(636/639) phosphorylation in the three tissues studied. Following T, E or combined supplementation to castrated rats, the pattern of IRS-1 serine phosphorylation was restored to normal control levels. Furthermore, orchidectomy decreased serum insulin and glucose oxidation in all three tissues, and this was restored by T and its combination with E replacement, whereas E alone had no effect. It is concluded from the present study that sex steroid deficiency induces impaired glucose oxidation in insulin responsive tissues, which is mediated through reduced IR expression, and increased IRS-1 serine phosphorylation.

Polycystic ovary syndrome in the pediatric population

Polycystic ovary syndrome (PCOS) is a common disorder characterized by hyperandrogenism and disordered gonadotropin secretion, often associated with insulin resistance. The syndrome, which modulates both hormonal and metabolic processes, is the most common endocrinopathy in reproductive-age women and increases a woman's risk of infertility, endometrial pathology, and cardiometabolic disease. As it is currently defined, PCOS most likely encompasses several distinct diseases with similar clinical phenotypes but different underlying pathophysiological processes. However, hyperandrogenism remains the syndrome's clinical hallmark. The clinical manifestations of PCOS often emerge during childhood or in the peripubertal years, suggesting that the syndrome is influenced by fetal programming and/or early postnatal events. However, given that the full clinical spectrum of PCOS does not typically appear until puberty, a "two-hit" hypothesis has been proposed: (1) a girl develops hyperandrogenism via one or more of many different potential mechanisms; (2) the preexisting hyperandrogenism subsequently disturbs the hypothalamic–pituitary–ovarian axis, resulting in ovulatory dysfunction and sustained hyperandrogenism. No consensus guidelines exist regarding the diagnosis and management of PCOS in the pediatric population; however, because the syndrome is a diagnosis of exclusion, the clinical evaluation of girls suspected of having PCOS is aimed at excluding other causes of androgen excess and menstrual dysfunction. For the syndrome's management, emphasis is placed on lifestyle and symptom-directed treatment.

Quantitative trait loci for fatness at growing and reproductive stages in Iberian × Meishan F(2) sows

A considerable number of fatness QTL have been identified in growing pigs, but there is a lack of knowledge about the genetic architecture of this trait in gilts and sows. We have performed a genome scan, in 255 Iberian × Meishan F(2) sows, for backfat thickness (BF) at 150 (BF(150) ) and 210 (BF(210)) days of age, 30 days after conception (BF(30)) and 7-10 days before farrowing (BF(bf)). We have found one BF150 QTL in SSC6 (120 cM) that was highly significant (P < 0.001) at the chromosome-wide level and suggestive at the genome-wide level (P < 0.1). Ten additional chromosome-wide significant QTL were found for sow BF(150) (SSC1, SSC13), BF(210) (SSC6, SSC8, SSC15), BF(30) (SSC5, SSC6) and BF(bf) (SSC1, SSC6, SSC13). The location of several of the BF QTL varied depending on the growing and reproductive status of the sow, suggesting that part of these genetic effects may have a temporal pattern of phenotypic expression.

The role of testosterone in the etiology and treatment of obesity, the metabolic syndrome, and diabetes mellitus type 2

Obesity has become a major health problem. Testosterone plays a significant role in obesity, glucose homeostasis, and lipid metabolism. The metabolic syndrome is a clustering of risk factors predisposing to diabetes mellitus type 2, atherosclerosis, and cardiovascular morbidity and mortality. The main components of the syndrome are visceral obesity, insulin resistance, glucose intolerance, raised blood pressure and dyslipidemia (elevated triglycerides, low levels of high-density lipoprotein cholesterol), and a proinflammatory and thrombogenic state. Cross-sectional epidemiological studies have reported a direct correlation between plasma testosterone and insulin sensitivity, and low testosterone levels are associated with an increased risk of type 2 diabetes mellitus, dramatically illustrated by androgen deprivation in men with prostate carcinoma. Lower total testosterone and sex hormone-binding globulin (SHBG) predict a higher incidence of the metabolic syndrome. Administration of testosterone to hypogonadal men reverses part of the unfavorable risk profile for the development of diabetes and atherosclerosis.

Effect of light intensity on broiler production, processing characteristics, and welfare

Manipulation of light intensity is an important management tool affecting broiler production and well being. Despite considerable research on light intensity, there is still a debate on the optimum level to be used for intensively housed broilers. Two trials were conducted with the objective of investigating the effect of light intensity, within the practical levels at confinement barns (1, 10, 20, and 40 lx), on production, processing characteristics, and welfare of broilers raised to 35 d of age. Each light intensity treatment was replicated in 2 environmentally controlled rooms in each trial with 950 Ross × Ross 308 chicks per room. Data were analyzed as a randomized complete block design with trial serving as a block. All chicks were exposed to 40 lx of light intensity and 23 h of light for the first 7 d followed by treatment light intensity and 17 h of day length thereafter. Body weight and feed consumption were determined at 7, 14, and 35 d of age. At the end of each trial, 60 birds per treatment were processed to determine the detailed meat yield. Skeletal and footpad and ocular health were monitored at 31 and 32 d of age, respectively. Body weight, feed consumption, feed:gain ratio, and mortality were unaffected by light intensity. Carcass, thigh, and drum yield as a percentage of live weight decreased linearly with increasing light intensity. The 1 lx treatment resulted in heavier wings as a percentage of live weight. Light intensity had no effect on skeletal health, but ulcerative footpad lesions decreased linearly with increasing light intensity. Birds exposed to the 1 lx treatment had heavier and larger eyes. In conclusion, light intensity did not affect broiler production and mortality but did affect carcass characteristics. The 1 lx light intensity treatment had a negative effect on broiler welfare as demonstrated by increased ulcerative footpad lesions and eye size.

Body weight decreases induced by estradiol in female rhesus monkeys are dependent upon social status

Gonadal steroids regulate appetite and thus body weight. In addition, continuous exposure to stressors negatively influences appetite through circuits likely distinct from those of gonadal steroids. The occurrence of adverse metabolic consequences due to chronic exposure to psychosocial stressors is twice as frequent in women as men, implicating a role for ovarian hormones, estradiol (E2) and progesterone (P4), in modulating stress-induced changes in appetite. Using social subordination in female macaques as a model of social stress, the current study tested the hypothesis that subordinate females would lose more weight during E2 treatment and gain less weight during P4 administration than dominant females. Because polymorphisms in the gene encoding the serotonin transporter (5HTT; SCL6A4) are known to alter responsivity to stress, we hypothesized that weight loss during E2 administration would be greatest in females with the short variant (s-variant) allele of 5HTT. Dominant females were significantly heavier than subordinate animals throughout the study, a result consistent with previous accounts of food intake when animals are fed a low-fat, high-fiber diet. Females with the s-variant 5HTT genotype weighed significantly less than l/l animals. Dominant animals lost significantly more weight than subordinate animals during E2 treatment. Administration of P4 blocked the weight-reducing effects of E2 in all females, regardless of social status. These data provide evidence that social subordination modulates the influence of ovarian steroid hormones on body weight in female rhesus monkeys independent of 5HTT genotype. Given the prosocial effects of these steroids, future studies are necessary to determine whether status differences in E2-induced weight loss are due to diminished food intake and or increases in energy expenditure and how the change in energy availability during E2 treatments relates to a female's motivation to interact with conspecifics.

High-fat diet-induced obesity in animal models

Epidemiological studies have shown a positive relationship between dietary fat intake and obesity. Since rats and mice show a similar relationship, they are considered an appropriate model for studying dietary obesity. The present paper describes the history of using high-fat diets to induce obesity in animals, aims to clarify the consequences of changing the amount and type of dietary fats on weight gain, body composition and adipose tissue cellularity, and explores the contribution of genetics and sex, as well as the biochemical basis and the roles of hormones such as leptin, insulin and ghrelin in animal models of dietary obesity. The major factors that contribute to dietary obesity - hyperphagia, energy density and post-ingestive effects of the dietary fat - are discussed. Other factors that affect dietary obesity including feeding rhythmicity, social factors and stress are highlighted. Finally, we comment on the reversibility of high-fat diet-induced obesity.

Gene expression profiling of murine hepatic steatosis induced by tamoxifen

Tamoxifen is an antiestrogenic agent used widely in the treatment of estrogen receptor-positive breast cancer. However, hepatic steatosis has been reported during clinical trials of tamoxifen. To explore the mechanism responsible for this tamoxifen-induced hepatic steatosis, we used microarray analysis to profile the gene expression pattern of mouse liver after tamoxifen treatment. Tamoxifen was administered orally as a single dose of 10mg/kg (low dose), 50mg/kg (medium dose), or 100mg/kg (high dose) to C57BL/6 mice, and the livers were removed 2h, 4h, 8h, and 24h later. From microarray data obtained from the liver samples, 414 genes were selected as tamoxifen-responsive genes (P<0.05, two-way ANOVA; cutoff ≥ 1.5-fold response). These genes were classified into three groups: 308 of the 414 genes showed a time-dependent response, nine genes showed a dose-dependent response, and 97 genes showed a time- and dose-dependent response. Most of the 308 time-dependent-responsive genes were associated predominantly with the biological processes involved in lipid metabolism. Overrepresented transcription factor binding site analysis showed that the following nuclear receptors that are important in lipid and carbohydrate metabolism were overrepresented: the androgen receptor (AR), nuclear receptor subfamily 2 group F member 1 (NR2F1), hepatocyte nuclear factor 4α (HNF4α), and retinoic acid receptor-related orphan receptor alpha 1 (RORα1). Reporter gene analysis further revealed that tamoxifen repressed the 5α-dihydrotestosterone-induced activation of the AR and the intrinsic transactivation function of RORα1, HNF4α, and NR2F1. Taken together, these data provide a better understanding of the molecular mechanism underlying tamoxifen-induced steatogenic hepatotoxicity and useful information for predicting steatogenic hepatotoxicity.

Sex- and depot-dependent differences in adipogenesis in normal-weight humans

To elucidate cellular mechanisms of sex-related differences in fat distribution, we determined body fat distribution (dual-energy X-ray absorptiometry and single-slice abdominal computed tomography (CT)), adipocyte size, adipocyte number, and proportion of early-differentiated adipocytes (aP2(+)CD68(-)) in the stromovascular fraction (SVF) in the upper and lower body of normal-weight healthy men (n = 12) and premenopausal women (n = 20) (age: 18-49 years, BMI: 18-26 kg/m(2)). Women had more subcutaneous and less visceral fat than men. The proportion of early differentiated adipocytes in the subcutaneous adipose tissue SVF of women was greater than in men (P = 0.01), especially in the femoral depot, although in vitro adipogenesis, as assessed by peroxisome proliferator activated receptor-γ (PPARγ) expression, was not increased in femoral preadipocytes cultured from women compared with men. In women, differentiation of femoral preadipocytes was less than that of abdominal subcutaneous preadipocytes (P = 0.04), and femoral subcutaneous preadipocytes tended to be more resistant to tumor necrosis factor-α (TNFα)-induced apoptosis (P = 0.06). Thus, turnover and utilization of the preadipocyte pool may be reduced in lower vs. the upper-body fat in women. Collectively, these data indicate that the microenvironment, rather than differences in inherent properties of preadipocytes between genders, may explain the gynoid obesity phenotype and higher percent body fat in women compared to men.

Metabolic disorders in newly diagnosed young adult female patients with simple virilizing 21-hydroxylase deficiency

Classical congenital adrenal hyperplasia (CAH) is characterized by the defects in cortisol and aldosterone secretion, and accompanied with adrenal hyperandrogenism. It is likely that the impaired adrenocortical function and intermittent treatment-related hypercortisolism may predispose patients to the development of metabolic syndrome in adulthood. Our aim was to assess the impact of hyperandrogenism on metabolic profiles in CAH women without glucocorticosteroid treatment. We evaluated the clinical characteristics and metabolic profiles in 30 untreated Chinese female adults with simple virilizing congenital adrenal hyperplasia (SV-CAH). Mutation analysis was performed by sequencing the entire 21-hydroxylase gene (CYP21A2). As compared with the controls, CAH patients had higher BMI (BMI, 21.5±2.1 vs. 20.0±1.8 kg/m2, P<0.05), higher 2 h post-load plasma glucose levels (6. 35±1.74 vs. 5. 35±1.17 mmol/l, P<0.05), higher serum triglycerides (TG) (1.12±0.64 vs. 0.63±0.15 mmol/l, P<0.01), and lower high-density lipoprotein cholesterol (HDL-c) (1.30±0.39 vs. 1.67±0.29 mmol/l, P<0.01). Moreover, CAH patients had higher fasting insulin and homeostasis model assessment of insulin resistance (HOMA-IR) (1.81±0.99 vs. 1.24±0.50, P<0.05), while ΔIns30/ΔGlu30 showed no statistically significant difference in two groups. In addition, a marked reduction of serum adiponectin levels were observed in CAH patients (7.0±3.3 vs. 13.2±4.8 μg/ml, P<0.001), however, serum CRP levels were not different between patients and the controls. Further regression analysis showed that higher serum testosterone concentrations were associated with metabolic disorder indexes and reduction of serum adiponectin. Our study demonstrates that untreated CAH patients are prone to have metabolic disorders in association with elevated serum testosterone levels and reduced insulin insensitivity.

Estrogen sulfotransferase regulates body fat and glucose homeostasis in female mice

Estrogen regulates fat mass and distribution and glucose metabolism. We have previously found that estrogen sulfotransferase (EST), which inactivates estrogen through sulfoconjugation, was highly expressed in adipose tissue of male mice and induced by testosterone in female mice. To determine whether inhibition of estrogen in female adipose tissue affects adipose mass and metabolism, we generated transgenic mice expressing EST via the aP2 promoter. As expected, EST expression was increased in adipose tissue as well as macrophages. Parametrial and subcutaneous inguinal adipose mass and adipocyte size were significantly reduced in EST transgenic mice, but there was no change in retroperitoneal or brown adipose tissue. EST overexpression decreased the differentiation of primary adipocytes, and this was associated with reductions in the expression of peroxisome proliferator-activated receptor-γ, fatty acid synthase, hormone-sensitive lipase, lipoprotein lipase, and leptin. Serum leptin levels were significantly lower in EST transgenic mice, whereas total and high-molecular-weight adiponectin levels were not different in transgenic and wild-type mice. Glucose uptake was blunted in parametrial adipose tissue during hyperinsulinemic-euglycemic clamp in EST transgenic mice. In contrast, hepatic insulin sensitivity was improved but muscle insulin sensitivity did not change in EST transgenic mice. These results reveal novel effects of EST on adipose tissue and glucose homeostasis in female mice.

Body composition as determinant of thrombin generation in plasma: the Hoorn study

OBJECTIVE

The association between obesity and cardiovascular disease and venous thromboembolism might, at least partially, be explained by a hypercoagulable state. The extent to which body fat mass and its distribution contribute to a hypercoagulable state is unknown. In this study, we investigated the association between body composition and thrombin generation and evaluated the potential mediating role of low-grade inflammation.

METHODS AND RESULTS

We studied 586 individuals from the Hoorn Study (mean age, 69.7 ± 6.5 years, 298 women) in whom body composition was assessed by whole body dual-energy absorptiometry. Thrombin generation was measured using the calibrated automated thrombogram. Multiple regression analyses showed a positive association between total body fat and thrombin generation in women but not in men. In addition, detailed analyses of regional body composition showed that central but not peripheral fat mass was associated with greater thrombin generation and that there was a trend toward an inverse association with peripheral lean mass. The reported positive associations were partially attenuated by low-grade inflammation, however.

CONCLUSIONS

Body fat mass, in particular a central pattern of fat distribution, is associated with higher levels of thrombin generation in elderly women but not in men. This association may partially be explained by adiposity-related low-grade inflammation, but this hypothesis needs to be further investigated in mechanistic/prospective studies.

Hormone and pharmaceutical regulation of ASP production in 3T3-L1 adipocytes

Several studies have demonstrated increases in acylation stimulating protein (ASP), and precursor protein C3 in obesity, diabetes and dyslipidemia, however the nature of the regulation is unknown. To evaluate chronic hormonal and pharmaceutical mediated changes in ASP and potential mechanisms, 3T3-L1 adipocytes were treated with physiological concentrations of relevant hormones and drugs currently used in treatment of metabolic diseases for 48 h. Medium ASP production and C3 secretion were evaluated in relation to changes in adipocyte lipid metabolism (cellular triglyceride (TG) mass, non-esterified fatty acid (NEFA) release and real-time FA uptake). Chylomicrons increased ASP production (up to 411 +/- 133% P < 0.05), while leptin, triiodothyronine, and beta-blockers atenolol and propranolol had no effect. Dexamethasone, lovastatin, rosiglitazone and rimonabant decreased ASP production (-53 to -85%, P < 0.05), associated with a decrease in the precursor protein C3 (-37% to -65%, P < 0.01). By contrast, epinephrine, progesterone, testosterone, angiotensin II and metformin also decreased ASP (-54% to -100%, P < 0.05), but without change in precursor protein C3, suggesting a direct effect on convertase activity, possibly mediated by interference (except metformin) due to marked increases in NEFA (5.6-31-fold, increased P < 0.05). Both lovastatin and metformin induced decreases in ASP were also associated with decreased TG mass (maximal -60%, P < 0.05) and real-time FA uptake (maximum -75%, P < 0.05), suggesting a change in adipocyte differentiation status. These in vitro results are consistent with in vivo ASP profiles in subjects, and suggest that ASP may be regulated through precursor C3 availability, convertase activity and differentiation status.

Novel anti-adipogenic activity produced by human fibroblasts

Fatty tissue is generally found in distinct "depots" distributed throughout the human body. Adipocytes from each of the various depots differ in their metabolic capacities and their responses to environmental stimuli. Although a general understanding of the factors responsible for adipogenic transformation has been achieved, much is not understood about the mechanisms of adipose tissue deposition and the phenotypes of the adipocytes found within each depot. A clue to the factors regulating fat deposition may come from studies of adipogenesis using primary human orbital fibroblasts from patients with thyroid eye disease, a condition in which intense inflammation leads to expansion of orbital adipose tissue via differentiation of fibroblasts to adipocytes. We have previously demonstrated that adipogenesis of orbital fibroblasts is negatively correlated with cellular expression of the Thy-1 surface marker. In this study, we developed a novel imaging flow cytometric approach for the assessment of adipogenesis to test the hypothetical dependence of adipogenic potential on lack of Thy-1 expression. Using this technique, we learned that Thy-1-positive fibroblasts are, in fact, capable of differentiating into adipocytes but are less likely to do so because they secrete a paracrine anti-adipogenic factor. It is possible that such a factor plays an important role in the prevention of excess fat deposition in the normal orbit and may even be exploited as a therapy for the treatment of obesity, a major worldwide health concern.

Obesity in women

Obesity carries a unique disease burden on women and is influenced by a variety of biological, hormonal, environmental, and cultural factors. Reproductive transitions, such as pregnancy and menopause, increase the risk for obesity. Psychologically, obese women experience greater weight-related stigma and discrimination and are at increased risk for depression than obese men. Women are also particularly susceptible to psychological stress, sleep debt, and lack of physical activity, all of which are risk factors for the development of excess weight. Obesity risk is increased among women with psychiatric disorders and those who use certain psychotropic medications. Obesity treatment should take into consideration degree of obesity, health risks, past weight loss attempts, and individual differences in motivation and readiness for treatment.

Estrogen receptor mediates the effects of pseudoprotodiocsin on adipogenesis in 3T3-L1 cells

Estrogen receptors (ERs) play a pivotal role in adipogenesis; therefore, compounds targeting ERs may also affect fat formation. Recent studies have shown that the Dioscorea plant (commonly called yam) exhibits an antiobesity effect on rodents. However, the active compounds and underlying mechanisms responsible for this effect are not yet fully understood. We evaluated the effects of pseudoprotodiocsin (PPD), a steroid saponin from Dioscorea nipponica Makino (a type of Dioscorea), on adipogenesis and the mechanisms underlying this effect. Treatment with PPD at the onset of adipogenic differentiation resulted in significantly decreased adipogenesis in both in vitro and in vivo experimental systems. An increased amount of ERalpha mRNA, protein, and the accumulation of ERalpha in the nucleus were also observed. However, the expression pattern of ERbeta was not altered. Furthermore, the antiadipogenic effect of PPD was found to be ER dependent. It was also accompanied by the decreased expression of several genes involved in adipogenesis, including lipoprotein lipase (LPL), leptin, CCAAT/enhancer-binding-protein-alpha (C/EBPalpha), and peroxisome proliferator-activated receptor-gamma (PPARgamma), as well as the increased expression of some negative factors of adipogenesis, including preadipocyte factor 1 (Pre-1), GATA-binding protein 2 (GATA-2), GC-induced leucine-zipper protein (GILZ), and C/EBP homologous protein (CHOP-10). In addition to its estrogenic action, PPD also abolished the p38 mitogen-activated protein kinase (p38 MAPK) activation. Our results suggest that PPD inhibits adipogenesis in an ER-dependent manner and induces the expression of ERalpha. These findings may provide a lead toward a novel agent that can be used to treat obesity.

The weight gain response to stress during adulthood is conditioned by both sex and prenatal stress exposure

Food intake and weight gain are known to be affected by stress. However, the type and duration of the stress may have variable effects, with males and females responding differently. We report the short-term and long-term effects of prenatal and adult immobilization stress, as well as the combination of these two stresses, on weight gain and food intake in male and female rats and the role of post-pubertal gonadal hormones in this process. No long-term effect of prenatal stress on food intake or weight gain was found in either sex. However, during the period of adult stress [at postnatal day (P) 90; 10 days duration] stressed male rats gained significantly less weight than controls and previous exposure to prenatal stress attenuated this effect (control: 31.2+/-2.1g; prenatal stress: 24.6+/-3.8g; adult stress: 8.1+/-3.4g; prenatal and adult stress: 18.2+/-3.3g; p<0.0001). There was no change in food intake in response to either prenatal or adult stress. Adult stress increased circulating corticosterone levels during the initial part of the stress period, in both male and female rats with this rise being greater in male rats. No effect on corticosterone levels was observed on the last day of stress in either sex. No effect on weight gain or food intake was observed in female rats. Following adult stress, male rats increased their weight gain, with no change in food intake, such that 1 month later they reached control levels. At the time of sacrifice (P180), there were no differences in weight or circulating metabolic hormone levels between any of the male groups. Although castration alone modulated body weight in both male and female rats, it did not affect their weight gain response to adult stress. These results indicate that the weight gain response to adult stress is sexually dimorphic and that this is not dependent on post-pubertal gonadal steroids. Furthermore, the outcome of this response closely depends on the time at which the change in weight is analyzed, which could help to explain different results reported in the literature. Indeed, weight and metabolic hormone levels were normalized by the end of the study.

Transplantation of adipose tissue and stem cells: role in metabolism and disease

Humans and other mammals have three main adipose tissue depots: visceral white adipose tissue, subcutaneous white adipose tissue and brown adipose tissue, each of which possesses unique cell-autonomous properties. In contrast to visceral adipose tissue, which can induce detrimental metabolic effects, subcutaneous white adipose tissue and brown adipose tissue have the potential to benefit metabolism by improving glucose homeostasis and increasing energy consumption. In addition, adipose tissue contains adipose-derived stem cells, which possess the ability to differentiate into multiple lineages, a property that might be of value for the repair or replacement of various damaged cell types. Adipose tissue transplantation has primarily been used as a tool to study physiology and for human reconstructive surgery. Transplantation of adipose tissue is, however, now being explored as a possible tool to promote the beneficial metabolic effects of subcutaneous white adipose tissue and brown adipose tissue, as well as adipose-derived stem cells. Ultimately, the clinical applicability of adipose tissue transplantation for the treatment of obesity and metabolic disorders will reside in the achievable level of safety, reliability and efficacy compared with other treatments.

Metabolic effects of 20-OH-ecdysone in ovariectomized rats

Postmenopausal women develop often obesity which may be prevented by 20-OH-Ecdysone (Ecd). This was investigated in ovariectomized (ovx) rats. They were orally treated with 3 doses of Ecd (18, 56 or 116 mg/day/animal). Positive controls received 159 microg estradiol (E2). Quantitative computer tomography at the level of the abdomen and the metaphysis of the tibia allowed estimation of surface, fat depots and muscles. The highest dose of Ecd resulted in serum concentrations of 0.4 x 10(-6)M. Serum E2 concentrations in the positive controls were 73.3+/-24.41 pg/ml. E2 but not Ecd stimulated uterine weights. Under Ecd ovx animals gained less fat but had more muscle mass. Serum TSH, T4 and T3 levels remained unaffected while E2 treatment increases T4 but decreases T3 levels. Ecd at the lowest dose lowered serum LDL and did not result in increased serum triglycerides, an effect seen in the E2 treated rats. At the Ecd highest dose serum HDL was higher than in the controls. In conclusion Ecd has beneficial effects on fat and muscle tissue and may be able to prevent the metabolic syndrome and sarcopenia by a non-estrogenic mechanism.

Estrogen reduces 11beta-hydroxysteroid dehydrogenase type 1 in liver and visceral, but not subcutaneous, adipose tissue in rats

Following menopause, body fat is redistributed from peripheral to central depots. This may be linked to the age related decrease in estrogen levels. We hypothesized that estrogen supplementation could counteract this fat redistribution through tissue-specific modulation of glucocorticoid exposure. We measured fat depot masses and the expression and activity of the glucocorticoid-activating enzyme 11beta-hydroxysteroid dehydrogenase type 1 (11betaHSD1) in fat and liver of ovariectomized female rats treated with or without 17beta-estradiol. 11betaHSD1 converts inert cortisone, or 11-dehydrocorticosterone in rats into active cortisol and corticosterone. Estradiol-treated rats gained less weight and had significantly lower visceral adipose tissue weight than nontreated rats (P < 0.01); subcutaneous adipose weight was unaltered. In addition, 11betaHSD1 activity/expression was downregulated in liver and visceral, but not subcutaneous, fat of estradiol-treated rats (P < 0.001 for both). This downregulation altered the balance of 11betaHSD1 expression and activity between adipose tissue depots, with higher levels in subcutaneous than visceral adipose tissue of estradiol-treated animals (P < 0.05 for both), opposite the pattern in ovariectomized rats not treated with estradiol (P < 0.001 for mRNA expression). Thus, estrogen modulates fat distribution, at least in part, through effects on tissue-specific glucocorticoid metabolism, suggesting that estrogen replacement therapy could influence obesity related morbidity in postmenopausal women.

Glyceollins, one of the phytoalexins derived from soybeans under fungal stress, enhance insulin sensitivity and exert insulinotropic actions

Glyceollins are a category of phytoalexins that are produced by soybeans under fungal stress, but their effects on glucose homeostasis remain unknown. We hypothesized that glyceollins play an important role in glucose homeostasis by regulating glucose utilization in adipocytes and improving beta-cell function and survival. Glyceollins improved insulin-stimulated glucose uptake in 3T3-L1 adipocytes without activating the peroxisome proliferator-activated receptor-gamma agonist. They decreased triacylglycerol accumulation in adipocytes. In addition, glyceollins slightly improved glucose-stimulated insulin secretion without palmitate treatment in Min6 cells, and they potentiated insulinotropic actions when 500 microM palmitate was used to induce beta-cell dysfunction. This was associated with decreased beta-cell apoptosis because of the attenuation of endoplasmic reticulum stress, as determined by mRNA levels of XBP-1, ATF-4, ATF-6, and CHOP. Glyceollins also potentiated GLP-1 secretion to enhance insulinotropic actions in enteroendocrine cells. In conclusion, glyceollins help normalize glucose homeostasis by potentiating beta-cell function and survival and improving glucose utilization in adipocytes.

Sex-dependent associations of leptin with metabolic syndrome-related variables: the Stanislas study

Serum leptin has been reported to be associated in a sex-dependent manner with C-reactive protein (CRP), independently of adiposity. We tested the hypothesis that leptin is associated, independently of anthropometry indexes and in a sex-dependent way, with other inflammatory markers and variables related to metabolic syndrome (MS). In 384 healthy middle-aged adults (192 men and 192 women) total fat mass (FM), waist circumference (WC), serum leptin and 15 MS-related parameters (systolic and diastolic blood pressure, triglycerides, cholesterol, high density lipoprotein (HDL)-cholesterol, apo AI and B, fasting glucose, uric acid, CRP, orosomucoid and haptoglobin levels and aspartate aminotransferase (ASAT), alanine aminotransferase (ALAT) and gamma-glutamyl transferase (GGT) activities) were measured. After adjustment for age, alcohol and cigarette consumption, WC, and total FM, leptin concentration was significantly associated with serum triglycerides, total cholesterol, apo B, uric acid and haptoglobin concentrations and liver enzyme activity only in men, and with apo AI, HDL-cholesterol (only borderline) and CRP only in women. Sex interaction terms were significant for total cholesterol, apo B, HDL cholesterol, uric acid, ALAT and GGT, and borderline significant for triglycerides, apo AI and ASAT. In this healthy population, leptin is significantly associated with various MS factors, independently of WC and total FM, depending on gender. Our study provides further evidence of sex-related differences mediated by leptin in inflammatory mechanisms and other MS-related metabolic pathways.

Association between anthropometric indicators of body fat and metabolic risk markers in post-menopausal women

OBJECTIVE

to evaluate anthropometric indicators of body fat and their association with metabolic risk markers in postmenopausal women.

METHODS

A cross-sectional study with 80 Brazilian women (40-70 years) was carried out. Body mass index (BMI = weight/height(2)), waist circumference (WC) and waist-to-hip ratio (WHR) were obtained for anthropometric evaluation. Trunk fat mass (TFM) was measured by dual-energy X-ray absorptiometry. The following metabolic variables were evaluated: total cholesterol (TC), HDL, LDL, triglycerides (TG), as well as glycemia and insulin to determine insulin resistance (HOMA-IR).

RESULTS

Overweight and obesity were observed in 81% of the women. Values of WC >88 cm were observed in 68.5% of the women. On average, TC, LDL and TG levels were above normal levels in 60, 50 and 42.5% of the women, respectively; and HDL was normal in 82.5%. IR was observed in 37.5% of the women. Positive correlations were found between anthropometric indicators and TFM (P < 0.05). WC was most correlated with TFM (r = 0.92), followed by BMI (r = 0.88) and by WHR (r = 0.48; P < 0.05). All anthropometric indicators and TFM showed significant negative correlations with HDL and significant positive correlations with HOMA-IR (P < 0.05). Only WHR was significantly associated with dysglycemia (R(2) = 12%), hypertriglyceridemia (R(2) = 17%) and decreased HDL (R(2) = 27%). WC was significantly associated with HOMA-IR (R(2) = 34%).

CONCLUSION

WC and WHR are anthropometric measures that showed strong correlation with TFM and with metabolic risk markers in postmenopausal women.

The ZEB1 transcription factor is a novel repressor of adiposity in female mice

Background

Four genome-wide association studies mapped an “obesity” gene to human chromosome 10p11–12. As the zinc finger E-box binding homeobox 1 (ZEB1) transcription factor is encoded by the TCF8 gene located in that region, and as it influences the differentiation of various mesodermal lineages, we hypothesized that ZEB1 might also modulate adiposity. The goal of these studies was to test that hypothesis in mice.

Methodology/Principal Findings

To ascertain whether fat accumulation affects ZEB1 expression, female C57BL/6 mice were fed a regular chow diet (RCD) ad libitum or a 25% calorie-restricted diet from 2.5 to 18.3 months of age. ZEB1 mRNA levels in parametrial fat were six to ten times higher in the obese mice. To determine directly whether ZEB1 affects adiposity, wild type (WT) mice and mice heterozygous for TCF8 (TCF8+/−) were fed an RCD or a high-fat diet (HFD) (60% calories from fat). By two months of age on an HFD and three months on an RCD, TCF8+/− mice were heavier than WT controls, which was attributed by Echo MRI to increased fat mass (at three months on an HFD: 0.517±0.081 total fat/lean mass versus 0.313±0.036; at three months on an RCD: 0.175±0.013 versus 0.124±0.012). No differences were observed in food uptake or physical activity, suggesting that the genotypes differ in some aspect of their metabolic activity. ZEB1 expression also increases during adipogenesis in cell culture.

Conclusion/Significance

These results show for the first time that the ZEB1 transcription factor regulates the accumulation of adipose tissue. Furthermore, they corroborate the genome-wide association studies that mapped an “obesity” gene at chromosome 10p11–12.

Testosterone deficiency, insulin resistance and the metabolic syndrome

Changing lifestyles and an excess of food supply in developed countries have resulted in an increasing prevalence of overweight and obesity. As a consequence, a disorder of complex pathophysiology involving visceral adipose tissue as an endocrine organ, dyslipidemia, insulin resistance and hypertension has emerged-the so-called metabolic syndrome. This disorder can lead to the manifestation of type 2 diabetes mellitus and cardiovascular disease. In men, testosterone deficiency may contribute to the development of the metabolic syndrome. In turn, states of hyperinsulinemia and obesity lead to a reduction of testicular testosterone production. Testosterone has reciprocal effects on the generation of muscle and visceral adipose tissue by influencing the commitment of pluripotent stem cells and by inhibiting the development of preadipocytes. Insulin sensitivity of muscle cells is increased by augmenting mitochondrial capacity and fostering expression of oxidative phosphorylation genes. Testosterone has a protective effect on pancreatic beta cells, which is possibly exerted by androgen-receptor-mediated mechanisms and influence of inflammatory cytokines. As some, but not all, epidemiological and interventional studies indicate, testosterone substitution might be helpful in preventing or attenuating the metabolic syndrome in aging men with late-onset hypogonadism and in hypogonadal patients with type 2 diabetes mellitus, but larger controlled trials are needed to confirm such hypotheses.

Sex steroids deficiency impairs glucose transporter 4 expression and its translocation through defective Akt phosphorylation in target tissues of adult male rat

There is a substantial body of evidence suggesting that altered level of sex steroids in male is associated with insulin resistance and type 2 diabetes mellitus. However, the mechanism of this effect is not apparent. Our recent study indicated that testosterone deprivation decreases insulin receptor expression and glucose oxidation in insulin target tissues. The present study was designed to assess the impact of deficiency of testosterone and estradiol on Akt phosphorylation, glucose transporter expression, and glucose uptake in skeletal muscle, adipose tissue, and liver of adult male rat. Adult male albino rats of Wistar strain were orchidectomized and supplemented with testosterone (100 microg/100 g body weight per day), estradiol (5 microg/100 g body weight per day), and their combination (100 microg testosterone plus 5 microg estradiol per 100 g body weight per day) for 15 days from the 11th day postorchidectomy. On the day after the last treatment, animals were perfused; and blood was collected for the assay of plasma glucose, serum insulin, testosterone, and estradiol. Gastrocnemius muscle, adipose tissue, and liver were dissected out and used for the assay of various parameters such as Akt phosphorylation, glucose transporter (GLUT) 2 and 4 expression, glucose uptake, and glycogenic and glycogenolytic enzymes activity. Castration elevated the blood glucose level, which was accompanied by inhibitory effect on serum insulin, Akt phosphorylation, GLUT4 expression and its plasma membrane population, glucose uptake, glycogen and glycogen synthase activity, and stimulatory effect on GLUT2 expression and glycogen phosphorylase activity in tissues studied. After testosterone and its combination with estradiol supplementation to castrated rats, a normal pattern of all these parameters was restored. Estradiol administration to castrated rats increased the Akt phosphorylation without altering other parameters studied. It is concluded from the present study that sex steroids deficiency-induced defective glucose uptake in skeletal muscle and adipose tissue is mediated through defective Akt phosphorylation and GLUT4 expression in plasma membrane.

A longitudinal comparison of body composition changes in adolescent girls receiving hormonal contraception

The objective of this study was to examine body composition changes in adolescent girls initiating depot medroxyprogesterone acetate (DMPA), oral contraceptives, or no hormonal contraceptive method. At 6 months, DMPA resulted in significant increases in adiposity with concomitant decreases in lean body mass. Supplemental estrogen may lessen these DMPA effects.