The regulation of HSL and LPL expression by DHT and flutamide in human subcutaneous adipose tissue

White-brown adipose tissue interplay in polycystic ovary syndrome: Therapeutic avenues

This study highlights the therapeutic potential of activating brown adipose tissue (BAT) for managing polycystic ovary syndrome (PCOS), a prevalent endocrine disorder associated with metabolic and reproductive abnormalities. BAT plays a crucial role in regulating energy expenditure and systemic insulin sensitivity, making it an attractive target for the treatment of obesity and metabolic diseases. Recent research suggests that impaired BAT function and mass may contribute to the link between metabolic disturbances and reproductive issues in PCOS. Additionally, abnormal white adipose tissue (WAT) can exacerbate these conditions by releasing adipokines and nonesterified fatty acids. In this review, we explored the impact of WAT changes on BAT function in PCOS and discussed the potential of BAT activation as a therapeutic strategy to improve PCOS symptoms. We propose that BAT activation holds promise for managing PCOS; however, further research is needed to confirm its efficacy and to develop clinically feasible methods for BAT activation.

An overview on androgen-mediated actions in skeletal muscle and adipose tissue

Androgens are a class of steroid hormones primarily associated with male sexual development and physiology, but exert pleiotropic effects in either sex. They have a crucial role in various physiological processes, including the regulation of skeletal muscle and adipose tissue homeostasis. The effects of androgens are mainly mediated through the androgen receptor (AR), a ligand-activated nuclear receptor expressed in both tissues. In skeletal muscle, androgens via AR exert a multitude of effects, ranging from increased muscle mass and strength, to the regulation of muscle fiber type composition, contraction and metabolic functions. In adipose tissue, androgens influence several processes including proliferation, fat distribution, and metabolism but they display depot-specific and organism-specific effects which differ in certain context. This review further explores the potential mechanisms underlying androgen-AR signaling in skeletal muscle and adipose tissue. Understanding the roles of androgens and their receptor in skeletal muscle and adipose tissue is essential for elucidating their contributions to physiological processes, disease conditions, and potential therapeutic interventions.

Development and evaluation of novel krill oil-based clomiphene microemulsion as a therapeutic strategy for PCOS treatment

Polycystic ovary syndrome (PCOS) is frequently diagnosed hormonal disorder with reproductive and metabolic complications. The most common symptoms include cyst in ovaries, anovulation, insulin resistance, and obesity. Clomiphene citrate, an ovulating agent, is the first-line drug used to treat PCOS. We hypothesized that clomiphene citrate, by stimulating ovarian function, with krill oil used as an oil phase to improve solubility, by addressing PCOS-associated symptoms might be effective in PCOS. Hence, our goal was to target hormonal imbalance along with PCOS-associated symptoms using a single formulation. The concentration of water (X1), oil (X2), and Smix (surfactant-cosurfactant mixture) (X3) were selected as independent variables, in a simplex lattice design, from microemulsion area derived from a pseuodoternary phase diagram while the globule size (Y1) was selected as a dependent parameter. The optimized microemulsion showed good sphericity having 41 nm globule size, 0.32 poly dispersibility index and + 31 mV zeta potential. The optimized microemulsion was further evaluated in-vivo using letrozole-induced PCOS rats. Formulation treated group reversed the effect of letrozole on body weight and estrus cycle in comparison to the disease control group (p < 0.001). The formulation was also effective in reducing insulin resistance, cholesterol and serum testosterone level (p < 0.001). The in vivo results were supported by histopathological studies where the formulation-treated group showed a marked decrease in the number of cystic follicles and a remarkable increase in the number of growing follicles at variable stages, similar to the normal control group. Thus, the results confirmed that novel krill oil-based clomiphene microemulsion may become a promising therapeutic choice for the treatment of PCOS.

Broiler responses to copper levels and sources: growth, tissue mineral content, antioxidant status and mRNA expression of genes involved in lipid and protein metabolism

BACKGROUND

Five hundred 8-d old male broilers Cobb500 were randomly allotted into 10 treatments in factorial arrangement with 5 Cu levels (0, 4, 8, 12, and 16 mg/kg), and 2 sources (Cu proteinate, CuPro and Cu sulphate, CuSO4.5H2O) for a 10-d-experiment.

RESULTS

Feed conversion ratio (FCR) was better (P < 0.05) in CuPro fed chicks compared with CuSO4.5H2O group. Average daily feed intake (ADFI) decreased linearly (P < 0.05) as dietary Cu increased. A quadratic response (P < 0.05) to Cu levels was found for FCR, being optimized at 9.87 and 8.84 mg Cu/kg in CuPro and CuSO4.5H2O diets, respectively. Copper supplementation linearly increased liver Cu content (P < 0.05) and tended to linearly increase (P = 0.07) phosphorus (P) and copper in tibia. Manganese and zinc were higher (P < 0.05) in tibia of CuPro fed birds. Broilers fed CuPro exhibited lower liver iron (P < 0.05) content, lower activities of Cu, Zn superoxide dismutase (CuZnSOD) in breast muscle and liver, and glutathione peroxidase in liver. Glutathione peroxidase reduced linearly (P < 0.05) with CuPro levels and increased linearly (P < 0.05) with CuSO4.5H2O levels and were lower (P < 0.05) in all CuPro levels in breast muscle. Breast muscle malondialdehyde concentration tended to be higher (P = 0.08) in broilers fed CuSO4.5H2O. Copper levels linearly increased (P < 0.05) metallothionein (MT) and malate dehydrogenase (MDH) expression in liver, and six-transmembrane epithelial antigen of the prostate-1 (STEAP-1) in the intestine. Copper elicited a quadratic response (P < 0.050) in AKT-1 and mammalian target of rapamycin (mTOR) in breast muscle, CuZnSOD in liver and antioxidant 1 copper chaperone (ATOX 1) in intestine. Broilers fed CuPro exhibited higher mRNA expression of mTOR in muscle breast and lower CuZnSOD in liver and ATOX 1 in intestine. Interaction (P < 0.05) between levels and sources was found in mRNA expression for GSK-3β, MT, and CuZnSOD in breast muscle, FAS and LPL in liver and MT and CTR1 in intestine.

CONCLUSIONS

CuPro showed beneficial effects on feed conversion and bone mineralization. Organic and inorganic Cu requirements are 9.87 and 8.84 mg Cu/kg, respectively.

Lipid Metabolism and Epigenetics Crosstalk in Prostate Cancer

Prostate cancer (PCa) is the most commonly diagnosed malignant neoplasm in men in the Western world. Localized low-risk PCa has an excellent prognosis thanks to effective local treatments; however, despite the incorporation of new therapeutic strategies, metastatic PCa remains incurable mainly due to disease heterogeneity and the development of resistance to therapy. The mechanisms underlying PCa progression and therapy resistance are multiple and include metabolic reprogramming, especially in relation to lipid metabolism, as well as epigenetic remodelling, both of which enable cancer cells to adapt to dynamic changes in the tumour. Interestingly, metabolism and epigenetics are interconnected. Metabolism can regulate epigenetics through the direct influence of metabolites on epigenetic processes, while epigenetics can control metabolism by directly or indirectly regulating the expression of metabolic genes. Moreover, epidemiological studies suggest an association between a high-fat diet, which can alter the availability of metabolites, and PCa progression. Here, we review the alterations of lipid metabolism and epigenetics in PCa, before focusing on the mechanisms that connect them. We also discuss the influence of diet in this scenario. This information may help to identify prognostic and predictive biomarkers as well as targetable vulnerabilities.

Recent Update on the Molecular Mechanisms of Gonadal Steroids Action in Adipose Tissue

The gonadal steroids, including androgens, estrogens and progestogens, are involved in the control of body fat distribution in humans. Nevertheless, not only the size and localization of the fat depots depend on the sex steroids levels, but they can also highly affect the functioning of adipose tissue. Namely, the gonadocorticoids can directly influence insulin signaling, lipid metabolism, fatty acid uptake and adipokine production. They may also alter energy balance and glucose homeostasis in adipocytes in an indirect way, e.g., by changing the expression level of aquaglyceroporins. This work presents the recent advances in understanding the molecular mechanism of how the gonadal steroids influence the functioning of adipose tissue leading to a set of detrimental metabolic consequences. Special attention is given here to highlighting the sexual dimorphism of adipocyte functioning in terms of health and disease. Particularly, we discuss the molecular background of metabolic disturbances occurring in consequence of hormonal imbalance which is characteristic of some common endocrinopathies such as the polycystic ovary syndrome. From this perspective, we highlight the potential drug targets and the active substances which can be used in personalized sex-specific management of metabolic diseases, in accord with the patient's hormonal status.

Adipocyte and steroidogenic cell cross-talk in polycystic ovary syndrome

BACKGROUND

Metabolic and endocrine alterations in women with polycystic ovary syndrome (PCOS) affect adipose tissue mass and distribution. PCOS is characterised by hyperandrogenism, obesity and adipocyte dysfunction. Hyperandrogenism in PCOS drives dysfunctional adipocyte secretion of potentially harmful adipocytokines. Glucocorticoids and sex-steroids modulate adipocyte development and function. For their part, adipocyte products interact with adrenal and ovarian steroidogenic cells. Currently, the relationship between adipocyte and steroidogenic cells is not clear, and for these reasons, it is important to elucidate the interrelationship between these cells in women with and without PCOS.

OBJECTIVE AND RATIONALE

This comprehensive review aims to assess current knowledge regarding the interrelationship between adipocytes and adrenal and ovarian steroidogenic cells in animal models and humans with or without PCOS.

SEARCH METHODS

We searched for articles published in English and Portuguese in PubMed. Keywords were as follows: polycystic ovary syndrome, steroidogenesis, adrenal glands, theca cells, granulosa cells, adipocytes, adipocytokines, obesity, enzyme activation, and cytochrome P450 enzymes. We expanded the search into the references from the retrieved articles.

OUTCOMES

Glucocorticoids and sex-steroids modulate adipocyte differentiation and function. Dysfunctional adipocyte products play important roles in the metabolic and endocrine pathways in animals and women with PCOS. Most adipokines participate in the regulation of the hypothalamic-pituitary-adrenal and ovarian axes. In animal models of PCOS, hyperinsulinemia and poor fertility are common; various adipokines modulate ovarian steroidogenesis, depending on the species. Women with PCOS secrete unbalanced levels of adipocyte products, characterised by higher levels of leptin and lower levels of adiponectin. Leptin expression positively correlates with body mass index, waist/hip ratio and levels of total cholesterol, triglyceride, luteinising hormone, oestradiol and androgens. Leptin inhibits the production of oestradiol and, in granulosa cells, may modulate 17-hydroxylase and aromatase enzyme activities. Adiponectin levels negatively correlate with fat mass, body mass index, waist-hip ratio, glucose, insulin and triglycerides, and decrease androgen production by altering expression of luteinising hormone receptor, steroidogenic acute regulatory protein, cholesterol-side-chain cleavage enzyme and 17-hydroxylase. Resistin expression positively correlates with body mass index and testosterone, and promotes the expression of 17-hydroxylase enzyme in theca cells. The potential benefits of adipokines in the treatment of women with PCOS require more investigation.

WIDER IMPLICATIONS

The current data regarding the relationship between adipocyte products and steroidogenic cells are conflicting in animals and humans. Polycystic ovary syndrome is an excellent model to investigate the interrelationship among adipocyte and steroidogenic cells. Women with PCOS manifest some pathological conditions associated with hyperandrogenism and adipocyte products. In animals, cross-talk between cells may vary according to species, and the current review suggests opportunities to test new medications to prevent or even reverse several harmful sequelae of PCOS in humans. Further studies are required to investigate the possible therapeutic application of adipokines in women with obese and non-obese PCOS. Meanwhile, when appropriate, metformin use alone, or associated with flutamide, may be considered for therapeutic purposes.

Metabolic dysfunction in polycystic ovary syndrome: Pathogenic role of androgen excess and potential therapeutic strategies

Background

Polycystic ovary syndrome (PCOS) is the most common endocrinopathy among reproductive age women. Although its cardinal manifestations include hyperandrogenism, oligo/anovulation, and/or polycystic ovarian morphology, PCOS women often display also notable metabolic comorbidities. An array of pathogenic mechanisms have been implicated in the etiology of this heterogeneous endocrine disorder; hyperandrogenism at various developmental periods is proposed as a major driver of the metabolic and reproductive perturbations associated with PCOS. However, the current understanding of the pathophysiology of PCOS-associated metabolic disease is incomplete, and therapeutic strategies used to manage this syndrome's metabolic complications remain limited.

Scope of review

This study is a systematic review of the potential etiopathogenic mechanisms of metabolic dysfunction frequently associated with PCOS, with special emphasis on the metabolic impact of androgen excess on different metabolic tissues and the brain. We also briefly summarize the therapeutic approaches currently available to manage metabolic perturbations linked to PCOS, highlighting current weaknesses and future directions.

Major conclusions

Androgen excess plays a prominent role in the development of metabolic disturbances associated with PCOS, with a discernible impact on key peripheral metabolic tissues, including the adipose, liver, pancreas, and muscle, and very prominently the brain, contributing to the constellation of metabolic complications of PCOS, from obesity to insulin resistance. However, the current understanding of the pathogenic roles of hyperandrogenism in metabolic dysfunction of PCOS and the underlying mechanisms remain largely incomplete. In addition, the development of more efficient, even personalized therapeutic strategies for the metabolic management of PCOS patients persists as an unmet need that will certainly benefit from a better comprehension of the molecular basis of this heterogeneous syndrome.

Sex Steroid Hormones Regulate Leptin Transcript Accumulation and Protein Secretion in 3T3-L1 Cells

Leptin is an adipokine produced by fat cells that regulates food consumption and metabolic activity. Sexual dimorphism in leptin and fat stores have been observed in humans and rodents with females having more leptin and greater levels of subcutaneous fat than males. One potential mechanism leading to this dimorphism is steroid hormone regulated synthesis of transcripts encoding leptin. Identification of direct regulatory mechanisms is difficult in animals or primary adipocytes due to these intertwined dimorphisms. We used well-characterized 3T3-L1 murine adipocytes to demonstrate that dihydrotestosterone (DHT) reduced Leptin (Lep) transcript abundance and cytosolic and secreted leptin protein. The magnitude of this effect was greatest on secreted leptin, which was decreased by DHT to 30% of the control. In contrast, 17β-estradiol significantly increased the abundance of transcripts encoding leptin and increased secreted leptin to 230% of the control. Treatment with estrogen and androgen receptor antagonists had opposite effects on Lep transcript abundance to steroid treatments, indicating that these transcriptional effects are mediated through the canonical steroid hormone signaling pathways. These results indicate that short-term treatments with steroid hormones are sufficient to alter both Lep transcript accumulation and leptin protein secretion, and may play a role in the sexual dimorphism of this adipokine.

Effect of dietary copper addition on lipid metabolism in rabbits

The present study was conducted to investigate the effect of copper supplementation on lipid metabolism in rabbits. Our study showed dietary copper addition (5-45 mg/kg) increased body mass gain, but decreased fat and liver weights compared with those in the control group (P < 0.05). Copper (45 mg/kg) addition significantly increased the skeletal muscle weight, but inhibited cytoplasmic lipid accumulation in liver, skeletal muscle and adipose tissue (P < 0.05). Compared with the control group, dietary copper addition (45 mg/kg) significantly increased plasma triglyceride levels but decreased very low density lipoprotein levels (P < 0.05). Copper treatment significantly increased gene expression of carnitine palmitoyltransferase (CPT) 1, CPT2 and peroxisome proliferator-activated receptor (PPAR) a in liver (P < 0.05). In skeletal muscle, CPT1, CPT2, fatty acid transport protein, fatty acid-binding protein, and PPARa mRNA as well as phosphorylated AMP-activated protein kinase (AMPK) levels were significantly up-regulated by copper treatment (P < 0.05). Rabbits receiving copper supplementation had higher CPT1, CPT2, PPARa and hormone-sensitive lipase mRNA levels in adipose tissue (P < 0.05). In conclusion, copper promoted skeletal muscle growth and reduced fat accretion. PPARa signaling in liver, skeletal muscle and adipose tissues and AMPK signaling in skeletal muscle tissue were involved in the regulation of lipid metabolism by copper.

The role of sex steroids in white adipose tissue adipocyte function

With the increasing knowledge that gender influences normal physiology, much biomedical research has begun to focus on the differential effects of sex on tissue function. Sexual dimorphism in mammals is due to the combined effects of both genetic and hormonal factors. Hormonal factors are mutable particularly in females in whom the estrous cycle dominates the hormonal milieu. Given the severity of the obesity epidemic and the fact that there are differences in the obesity rates in men and women, the role of sex in white adipose tissue function is being recognized as increasingly important. Although sex differences in white adipose tissue distribution are well established, the mechanisms affecting differential function of adipocytes within white adipose tissue in males and females remain largely understudied and poorly understood. One of the largest differences in the endocrine environment in males and females is the concentration of circulating androgens and estrogens. This review examines the effects of androgens and estrogens on lipolysis/lipogenesis, adipocyte differentiation, insulin sensitivity and adipokine production in adipocytes from white adipose tissue with a specific emphasis on the sexual dimorphism of adipocyte function in white adipose tissue during both health and disease.

Hormone-sensitive lipase deficiency alters gene expression and cholesterol content of mouse testis

Hormone-sensitive lipase-knockout (HSL−/−) mice exhibit azoospermia for unclear reasons. To explore the basis of sterility, we performed the following three experiments. First, HSL protein distribution in the testis was determined. Next, transcriptome analyses were performed on the testes of three experimental groups. Finally, the fatty acid and cholesterol levels in the testes with three different genotypes studied were determined. We found that the HSL protein was present from spermatocyte cells to mature sperm acrosomes in wild-type (HSL+/+) testes. Spermiogenesis ceased at the elongation phase of HSL−/− testes. Transcriptome analysis indicated that genes involved in lipid metabolism, cell membrane, reproduction and inflammation-related processes were disordered in HSL−/− testes. The cholesterol content was significantly higher in HSL−/− than that in HSL+/+ testis. Therefore, gene expression and cholesterol ester content differed in HSL−/− testes compared to other testes, which may explain the sterility of male HSL−/− mice.

Western-style diet, sex steroids and metabolism

The evolutionary transition from hunting to farming was associated with introduction of carbohydrate-rich diets. Today, the increased consumption of simple sugars and high-fat food brought about by Western-style diet and physical inactivity are leading causes of the growing obesity epidemic in the Western society. The extension of human lifespan far beyond reproductive age increased the burden of metabolic disorders associated with overnutrition and age-related hypogonadism. Sex steroids are essential regulators of both reproductive function and energy metabolism, whereas their imbalance causes infertility, obesity, glucose intolerance, dyslipidemia, and increased appetite. Clinical and translational studies suggest that dietary restriction and weight control can improve metabolic and reproductive outcomes of sex hormone-related pathologies, including testosterone deficiency in men and natural menopause and hyperandrogenemia in women. Minimizing metabolic and reproductive decline through rationally designed diet and exercise can help extend human reproductive age and promote healthy aging. This article is part of a Special Issue entitled: Oxidative Stress and Mitochondrial Quality in Diabetes/Obesity and Critical Illness Spectrum of Diseases - edited by P. Hemachandra Reddy.

Updated survey of the steroid-converting enzymes in human adipose tissues

Over the past decade, adipose tissues have been increasingly known for their endocrine properties, that is, their ability to secrete a number of adipocytokines that may exert local and/or systemic effects. In addition, adipose tissues have long been recognized as significant sites for steroid hormone transformation and action. We hereby provide an updated survey of the many steroid-converting enzymes that may be detected in human adipose tissues, their activities and potential roles. In addition to the now well-established role of aromatase and 11β-hydroxysteroid dehydrogenase (HSD) type 1, many enzymes have been reported in adipocyte cell lines, isolated mature cells and/or preadipocytes. These include 11β-HSD type 2, 17β-HSDs, 3β-HSD, 5α-reductases, sulfatases and glucuronosyltransferases. Some of these enzymes are postulated to bear relevance for adipose tissue physiology and perhaps for the pathophysiology of obesity. This elaborate set of steroid-converting enzymes in the cell types of adipose tissue deserves further scientific attention. Our work on 20α-HSD (AKR1C1), 3α-HSD type 3 (AKR1C2) and 17β-HSD type 5 (AKR1C3) allowed us to clarify the relevance of these enzymes for some aspects of adipose tissue function. For example, down-regulation of AKR1C2 expression in preadipocytes seems to potentiate the inhibitory action of dihydrotestosterone on adipogenesis in this model. Many additional studies are warranted to assess the impact of intra-adipose steroid hormone conversions on adipose tissue functions and chronic conditions such as obesity, diabetes and cancer.

Potential effects of aerobic exercise on the expression of perilipin 3 in the adipose tissue of women with polycystic ovary syndrome: a pilot study

OBJECTIVE

Polycystic ovary syndrome (PCOS) is associated with reduced adipose tissue lipolysis that can be rescued by aerobic exercise. We aimed to identify differences in the gene expression of perilipins and associated targets in adipose tissue in women with PCOS before and after exercise.

DESIGN AND METHODS

We conducted a cross-sectional study in eight women with PCOS and eight women matched for BMI and age with normal cycles. Women with PCOS also completed a 16-week prospective aerobic exercise-training study. Abdominal subcutaneous adipose tissue biopsies were collected, and primary adipose-derived stromal/stem cell cultures were established from women with PCOS before 16 weeks of aerobic exercise training (n=5) and controls (n=5). Gene expression was measured using real-time PCR, in vitro lipolysis was measured using radiolabeled oleate, and perilipin 3 (PLIN3) protein content was measured by western blotting analysis.

RESULTS

The expression of PLIN1, PLIN3, and PLIN5, along with coatomers ARF1, ARFRP1, and βCOP was ∼ 80% lower in women with PCOS (all P<0.05). Following exercise training, PLIN3 was the only perilipin to increase significantly (P<0.05), along with coatomers ARF1, ARFRP1, βCOP, and SEC23A (all P<0.05). Furthermore, PLIN3 protein expression was undetectable in the cell cultures from women with PCOS vs controls. Following exercise training, in vitro adipose oleate oxidation, glycerol secretion, and PLIN3 protein expression were increased, along with reductions in triglyceride content and absence of large lipid droplet morphology.

CONCLUSIONS

These findings suggest that PLIN3 and coatomer GTPases are important regulators of lipolysis and triglyceride storage in the adipose tissue of women with PCOS.

Androgens, body fat Distribution and Adipogenesis

Androgens are regulators of important adipocyte functions such as adipogenesis, lipid storage, and lipolysis. Through depot-specific impact on the cells of each fat compartment, androgens could modulate body fat distribution patterns in humans. Testosterone and dihydrotestosterone have been shown to inhibit the differentiation of preadipocytes to lipid-storing adipocytes in several models including primary cultures of human adipocytes from both men and women. Androgen effects have also been observed on some markers of lipid metabolism such as LPL activity, fatty acid uptake, and lipolysis. Possible depot-specific and sex-specific effects have been observed in some but not all models. Transformation of androgen precursors to active androgens or their inactivation by enzymes that are expressed and functional in adipose tissue may contribute to modulate the local availability of active hormones. These phenomena, along with putative depot-specific interactions with glucocorticoids may contribute to human body fat distribution patterns.

Sex-dependent expression of caveolin 1 in response to sex steroid hormones is closely associated with development of obesity in rats

Caveolin-1 (CAV1) is a conserved group of structural membrane proteins that form special cholesterol and sphingolipid-rich compartments, especially in adipocytes. Recently, it has been reported that CAV1 is an important target protein in sex hormone-dependent regulation of various metabolic pathways, particularly in cancer and diabetes. To clarify distinct roles of CAV1 in sex-dependent obesity development, we investigated the effects of high fat diet (HFD) and sex steroid hormones on CAV1 expression in adipose tissues of male and female rats. Results of animal experiments revealed that estrogen (17-β-estradiol, E2) and androgen (dihydrotestosterone, DHT) had opposite effects on body weight gain as well as on the regulation of CAV1, hormone sensitive lipase (HSL) and uncoupling protein 1 (UCP1) in adipose tissues. Furthermore, sex hormone receptors and aromatase were differentially expressed in a sex-dependent manner in response to E2 and DHT treatments. In vivo data were confirmed using 3T3-L1 and HIB1B cell lines, where Cav1 knock down stimulated lipogenesis but suppressed sex hormone receptor signaling proteins. Most importantly, co-immunoprecipitation enabled the identification of previously unrecognized CAV1-interacting mitochondrial or lipid oxidative pathway proteins in adipose tissues. Taken together, current data showed that CAV1 may play important preventive role in the development of obesity, with more prominent effects in females, and proved to be an important target protein for the hormonal regulation of adipose tissue metabolism by manipulating sex hormone receptors and mitochondrial oxidative pathways. Therefore, we can report, for the first time, the molecular mechanism underlying the effects of sex steroid hormones in the sex-dimorphic regulation of CAV1.

Fat-reducing effects of dehydroepiandrosterone involve upregulation of ATGL and HSL expression, and stimulation of lipolysis in adipose tissue

Dehydroepiandrosterone (DHEA) reduces body fat in rodents and humans, and increases glycerol release from isolated rat epididymal adipocytes and human visceral adipose tissue explants. It suggests that DHEA stimulates triglyceride hydrolysis in adipose tissue; however, the mechanisms underlying this action are still unclear. We examined the effects of DHEA on the expression of adipose triglyceride lipase (ATGL) and hormone-sensitive lipase (HSL), the key enzymes of lipolysis, in rat epididymal white adipose tissue (eWAT). Male Wistar rats were fed a diet containing 0.6% DHEA for 2 weeks and eWAT was analyzed for mRNA and protein expression of ATGL and HSL, as well as mRNA expression of peroxisome proliferator-activated receptor γ 2 (PPARγ2) and its downstream target fatty acid translocase (FAT). Glycerol release from eWAT explants and serum free fatty acids (FFA) were also measured. Rats that received DHEA gained less weight, had 23% lower eWAT mass and 31% higher serum FFA levels than controls. Cultured explants of eWAT from DHEA-treated rats released 81% more glycerol than those from control rats. DHEA administration upregulated ATGL mRNA (1.62-fold, P<0.05) and protein (1.78-fold, P<0.05) expression as well as augmented HSL mRNA levels (1.36-fold, P<0.05) and Ser660 phosphorylation of HSL (2.49-fold, P<0.05). PPARγ2 and FAT mRNA levels were also increased in DHEA-treated rats (1.61-fold, P<0.05 and 2.16-fold, P<0.05; respectively). Moreover, ATGL, HSL, and FAT mRNA levels were positively correlated with PPARγ2 expression. This study demonstrates that DHEA promotes lipid mobilization in adipose tissue by increasing the expression and activity of ATGL and HSL. The effects of DHEA appear to be mediated, at least in part, via PPARγ2 activation, which in turn upregulates ATGL and HSL gene expression.

Androgen effects on adipose tissue architecture and function in nonhuman primates

The differential association of hypoandrogenism in men and hyperandrogenism in women with insulin resistance and obesity suggests that androgens may exert sex-specific effects on adipose and other tissues, although the underlying mechanisms remain poorly understood. Moreover, recent studies also suggest that rodents and humans may respond differently to androgen imbalance. To achieve better insight into clinically relevant sex-specific mechanisms of androgen action, we used nonhuman primates to investigate the direct effects of gonadectomy and hormone replacement on white adipose tissue. We also employed a novel ex vivo approach that provides a convenient framework for understanding of adipose tissue physiology under a controlled tissue culture environment. In vivo androgen deprivation of males did not result in overt obesity or insulin resistance but did induce the appearance of very small, multilocular white adipocytes. Testosterone replacement restored normal cell size and a unilocular phenotype and stimulated adipogenic gene transcription and improved insulin sensitivity of male adipose tissue. Ex vivo studies demonstrated sex-specific effects of androgens on adipocyte function. Female adipose tissue treated with androgens displayed elevated basal but reduced insulin-dependent fatty acid uptake. Androgen-stimulated basal uptake was greater in adipose tissue of ovariectomized females than in adipose tissue of intact females and ovariectomized females replaced with estrogen and progesterone in vivo. Collectively, these data demonstrate that androgens are essential for normal adipogenesis in males and can impair essential adipocyte functions in females, thus strengthening the experimental basis for sex-specific effects of androgens in adipose tissue.

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.

Reverse engineering adverse outcome pathways

The toxicological effects of many stressors are mediated through unknown, or incompletely characterized, mechanisms of action. The application of reverse engineering complex interaction networks from high dimensional omics data (gene, protein, metabolic, signaling) can be used to overcome these limitations. This approach was used to characterize adverse outcome pathways (AOPs) for chemicals that disrupt the hypothalamus-pituitary-gonadal endocrine axis in fathead minnows (FHM, Pimephales promelas). Gene expression changes in FHM ovaries in response to seven different chemicals, over different times, doses, and in vivo versus in vitro conditions, were captured in a large data set of 868 arrays. Potential AOPs of the antiandrogen flutamide were examined using two mutual information-based methods to infer gene regulatory networks and potential AOPs. Representative networks from these studies were used to predict network paths from stressor to adverse outcome as candidate AOPs. The relationship of individual chemicals to an adverse outcome can be determined by following perturbations through the network in response to chemical treatment, thus leading to the nodes associated with the adverse outcome. Identification of candidate pathways allows for formation of testable hypotheses about key biological processes, biomarkers, or alternative endpoints that can be used to monitor an AOP. Finally, the unique challenges facing the application of this approach in ecotoxicology were identified and a road map for the utilization of these tools presented.

Correlation of serum androgens with anthropometric and metabolic indices in healthy, nonobese postmenopausal women

OBJECTIVE

The role of testosterone in the regulation of metabolic and physiological function in men is well defined, but its role in women remains enigmatic. Thus, the present study sought to assess the contribution of endogenous circulating androgens to the regulation of metabolic function, body morphometry, and physical function in normal naturally postmenopausal women.

METHODS

Using a cross-sectional design, we measured serum androgens in a cohort of 29 naturally postmenopausal women and correlated the results with metabolic, morphometric, and functional outcome parameters. These included insulin sensitivity, whole-body fat and lean body mass, visceral/abdominal fat areasm and aerobic capacity.

RESULTS

Higher serum testosterone levels were related to greater maximal aerobic capacity and reduced adiposity. Additionally, higher serum dihydrotestosterone, dehydroepiandrosterone sulfate, androstenedione, and androstenetriol glucuronidate levels were correlated to greater insulin sensitivity.

CONCLUSION

In naturally postmenopausal women, endogenous androgens may play a role in the maintenance of beneficial patterns of metabolic, morphometric, and functional parameters.

Testosterone stimulates adipose tissue 11beta-hydroxysteroid dehydrogenase type 1 expression in a depot-specific manner in children

CONTEXT

Activation of the enzyme 11beta-hydroxysteroid dehydrogenase type 1 (11beta-HSD1) in adipose tissue results in the production of excess tissue glucocorticoids and the induction of adiposity and visceral obesity in particular. Androgens may affect body fat distribution by regulating the local metabolism of cortisol.

OBJECTIVE

Our objective was to study 11beta-HSD1 mRNA expression in abdominal sc and omental (om) adipose tissue in children after in vitro testosterone and cortisol treatment.

SUBJECTS AND METHODS

Paired fat biopsies (sc and om) were obtained from 19 boys (age 6-14 yr, body mass index 14.6-25.3 kg/m(2), BMI sd score SDS -1.6-3.1) undergoing open abdominal surgery. Pieces of adipose tissue were incubated with testosterone, cortisol, or both hormones for 24 h, whereupon mRNA expression of 11beta-HSD1 and hexose-6-phosphate dehydrogenase (H6PDH) were measured by real-time PCR, and 11beta-HSD1 enzyme activity was determined.

RESULTS

Testosterone treatment up-regulated 11beta-HSD1 mRNA expression compared with control incubations in the absence of testosterone (P < 0.05) in om adipose tissue. Testosterone and cortisol both increased 11beta-HSD1 mRNA expression in om but not sc adipose tissue in a depot-specific manner by 2.5- and 2.9-fold, respectively (P < 0.001). However, there was no synergistic effect of the two hormones. 11beta-HSD1 enzyme activity correlated positively to mRNA expression (r = 0.610; P = 0.001). Adipose tissue mRNA expression of H6PDH was affected in a similar fashion to 11beta-HSD1 after hormonal treatment.

CONCLUSIONS

Testosterone and cortisol stimulated 11beta-HSD1 and H6PDH mRNA expression and 11beta-HSD1 activity in om but not in sc adipose tissue. This suggests that these hormones may contribute to fat distribution and accumulation during childhood.

Role of androgen excess on metabolic aberrations and cardiovascular risk in women with polycystic ovary syndrome

Polycystic ovary syndrome (PCOS) is associated with a clustering of metabolic and cardiovascular risk factors. Insulin resistance is implicated as the major player in the metabolic abnormalities and contributes to the increased cardiovascular risk associated with the syndrome. However, androgen excess appears to participate as an independent parameter, which further aggravates the cardiovascular and metabolic aberrations in affected women with PCOS. The resultant impact of hyperandrogenemia possibly acquires clinical significance for women's health in the context of PCOS, particularly since recent data support an increased incidence of coronary artery disease and of cardiovascular events directly related to androgen levels in women with the syndrome.

Effects of androgens on insulin action in women: is androgen excess a component of female metabolic syndrome?

Hyperinsulinemia as a consequence of insulin resistance causes hyperandrogenemia in women. The objective was to review evidence for the converse situation, i.e. whether androgens adversely influence insulin action. Androgen excess could potentially contribute to the pathogenesis of insulin resistance in women with polycystic ovary syndrome (PCOS), metabolic syndrome/type 2 diabetes, and in obese peripubertal girls. An Entrez-PubMed search was conducted to identify studies addressing the relationship of androgens with metabolic syndrome/type 2 diabetes in women. Studies reporting outcomes of androgen administration, interventions to reduce androgen effects in hyperandrogenemic women, and basic studies investigating androgen effects on insulin target tissues were reviewed. Multiple studies showed associations between serum testosterone and insulin resistance or metabolic syndrome/type 2 diabetes risk in women, but their cross-sectional nature did not allow conclusions about causality. Androgen administration to healthy women was associated with development of insulin resistance. Intervention studies in women with hyperandrogenism were limited by small subject numbers and use of indirect methods for assessing insulin sensitivity. However, in three of the seven studies using euglycemic hyperinsulinemic clamps, reduction of androgen levels or blockade of androgen action improved insulin sensitivity. Testosterone administration to female rats caused skeletal muscle insulin resistance. Testosterone induced insulin resistance in adipocytes of women in vitro. In conclusion, the metabolic consequences of androgen excess in women have been under-researched. Studies of long-term interventions that lower androgen levels or block androgen effects in young women with hyperandrogenism are needed to determine whether these might protect against metabolic syndrome/type 2 diabetes in later life.

Gene expression analyses in cynomolgus monkeys provides mechanistic insight into high-density lipoprotein-cholesterol reduction by androgens in primates

Androgens increase muscle mass, decrease fat mass, and reduce high-density lipoprotein cholesterol (HDL), but the relationship between body composition, lipoprotein metabolism, and androgens has not been explained. Here we treated ovariectomized cynomolgus monkeys with 5alpha-dihydrotestosterone (DHT) or vehicle for 14 d and measured lipoprotein and triglycerides. Nuclear magnetic resonance analysis revealed that DHT dose-dependently reduced the cholesterol content of large HDL particles and decreased mean HDL particle size (P < 0.01) and also tended to lower low-density lipoprotein cholesterol without altering other lipoprotein particles. Liver and visceral fat biopsies taken before and after DHT treatment for 1 or 14 d were analyzed by genome-wide microarrays. In liver, DHT did not alter the expression of most genes involved in cholesterol synthesis or uptake but rapidly increased small heterodimer partner (SHP) RNA, along with concomitant repression of CYP7A1, a target of SHP transcriptional repression and the rate-limiting enzyme in bile acid synthesis. DHT regulation of SHP and CYP7A1 also occurs in rats, indicating a conserved mechanism. In adipose tissue, pathway analyses suggested coordinate regulation of adipogenesis, tissue remodeling, and lipid homeostasis. Genes encoding IGF-I and beta-catenin were induced, as were extracellular matrix, cell adhesion, and cytoskeletal components, whereas there was consistent down-regulation of genes involved in triacylglycerol metabolism. Interestingly, cholesterol ester transfer protein RNA was induced rapidly in monkey adipose tissue, whereas its inhibitor apolipoprotein CI was repressed. These data provide insight into the androgenic regulation of lipoprotein homeostasis and suggest that changes in adipose lipoprotein metabolism could contribute to HDL cholesterol reduction.

Androgens and body fat distribution

An important sex difference in body fat distribution is generally observed. Men are usually characterized by the android type of obesity, with accumulation of fat in the abdominal region, whereas women often display the gynoid type of obesity, with a greater proportion of their body fat in the gluteal-femoral region. Accordingly, the amount of fat located inside the abdominal cavity (intra-abdominal or visceral adipose tissue) is twice as high in men compared to women. This sex difference has been shown to explain a major portion of the differing metabolic profiles and cardiovascular disease risk in men and women. Association studies have shown that circulating androgens are negatively associated with intra-abdominal fat accumulation in men, which explains an important portion of the link between low androgens and features of the metabolic syndrome. In women, the low circulating sex hormone-binding globulin (SHBG) levels found in abdominal obesity may indirectly indicate that elevated free androgens are related to increased visceral fat accumulation. However, data on non SHBG-bound and total androgens are not unanimous and difficult to interpret for total androgens. These studies focusing on plasma levels of sex hormones indirectly suggest that androgens may alter adipose tissue mass in a depot-specific manner. This could occur through site-specific modulation of preadipocyte proliferation and/or differentiation as well as lipid synthesis and/or lipolysis in mature adipocytes. Recent results on the effects of androgens in cultured adipocytes and adipose tissue have been inconsistent, but may indicate decreased adipogenesis and increased lipolysis upon androgen treatment. Finally, adipose tissue has been shown to express several steroidogenic and steroid-inactivating enzymes. Their mere presence in fat indirectly supports the notion of a highly complex enzymatic system modulating steroid action on a local basis. Recent data obtained in both men and women suggest that enzymes from the aldoketoreductase 1C family are very active and may be important modulators of androgen action in adipose tissue.

Pathophysiology and types of dyslipidemia in PCOS

Polycystic ovary syndrome (PCOS) is an endocrinopathy that affects women of reproductive age. PCOS shares components with the metabolic syndrome and has broad health implications. Lipid abnormalities, including elevated low-density lipoprotein (LDL), triglyceride levels and decreased high-density lipoprotein (HDL), are often found in women with PCOS. It is clear that obesity, insulin resistance and hyperandrogenism coexist in PCOS, and have independent and interactive effects on dyslipidemia, although the mechanisms of these interactions remain elusive. Here, we review the types and pathophysiology of dyslipidemia associated with PCOS and its related conditions.

Transcriptomic characterization of the long-term dihydrotestosterone effects in adipose tissue

OBJECTIVE

To study the long-term transcriptomic effects of dihydrotestosterone (DHT) in adipose tissue. Fat distribution is regulated by sexual hormones. It is still unclear if androgens are promoting or reducing intra-abdominal fat accumulation.

RESEARCH METHODS AND PROCEDURES

Retroperitoneal adipose tissue were isolated from each group of gonadectomized (GDX) C57BL6 male mice treated with vehicle or DHT for 21 days. Serial analysis of gene expression (SAGE) was performed to generate approximately 150,000 SAGE tags from each sample.

RESULTS

Among the numerous genes regulated by DHT, transcripts involved in glycolysis, such as aldolase 1 A isoform and pyruvate kinase muscle as well as lipogenic transcripts, such as malic enzyme supernatant and ELOVL family member 6 elongation of long chain fatty acids were down-regulated by androgen supplementation. In contrast, transcripts involved in lipolysis and fatty acid oxidation, such as carboxylesterase 3, acetyl-coenzyme A acyltransferase 1, 3-ketoacyl-CoA thiolase B and enoyl-coenzyme A hydratase/3-hydroxyacyl coenzyme A dehydrogenase were up-regulated by DHT. Pro-apoptotic transcripts such as cell death-inducing DFFA-like effector c, BCL2/adenovirus E1B 19 kDa-interacting protein 1 NIP3 and -interacting protein 3-like were up-regulated by DHT, whereas transcripts involved in promotion of cell cycle such as cyclin D2 were down-regulated by DHT.

DISCUSSION

These results suggest that chronic androgen treatment may help to improve metabolic profile by regulating various critical pathways involved in adipose tissue physiology. In addition, several genes associated with a healthier metabolic profile, such as adiponectin and CD36 antigen, were up-regulated by 21 days of DHT treatment.

Effects of testosterone and estrogen treatment on lipolysis signaling pathways in subcutaneous adipose tissue of postmenopausal women

OBJECTIVE

The aim of this study was to investigate the treatment effects of testosterone and estrogen on the expression of proteins and genes involved in adipocyte signal transduction to lipolysis in abdominal subcutaneous adipose tissue of postmenopausal women.

DESIGN

An open, randomized clinical study with parallel group comparison.

SETTING

Women's health clinical research unit and a research laboratory at a university hospital.

PATIENT(S)

Thirty-six healthy naturally postmenopausal women.

INTERVENTION(S)

The participants were randomly given testosterone undecanoate (40 mg every second day) or estradiol valerate (2 mg daily) for 3 months.

MAIN OUTCOME MEASURE(S)

Expression of proteins and genes involved in adipocyte signal transduction to lipolysis in abdominal subcutaneous adipose tissue, determined by quantitative real-time polymerase chain reaction and Western blot, respectively, and related to plasma glycerol before or during a euglycemic hyperinsulinemic clamp.

RESULT(S)

Testosterone treatment decreased the expression of hormone-sensitive lipase and increased the expression of phosphodiesterase-3B, whereas no effect of estrogen was observed. Testosterone-induced changes in hormone-sensitive lipase expression correlated positively with corresponding changes in basal or clamp-induced plasma glycerol concentrations.

CONCLUSION(S)

Treatment with testosterone in postmenopausal women down-regulates hormone-sensitive lipase and up-regulates phosphodiesterase-3B expressions in abdominal subcutaneous adipose tissue in relation to changes in vivo of lipolytic activity, which may promote the accumulation of fat.

Testosterone and erectile function: from basic research to a new clinical paradigm for managing men with androgen insufficiency and erectile dysfunction

OBJECTIVES

Androgens are essential for the development and growth of the penis, and they regulate erectile physiology by multiple mechanisms. Our goal is to provide a concise overview of the basic research and how this knowledge can be translated into a new clinical paradigm for patient management. In addition, this new paradigm may serve as a basis for stimulating constructive debate regarding the use of testosterone in men, and to promote new, innovative basic and clinical research to further understand the underlying mechanisms of androgen action in restoring erectile physiology.

METHODS

A literature review was performed utilizing the US National Library of Medicine's PubMed database.

RESULTS

On the basis of evidence derived from laboratory animal studies and clinical data, we postulate that androgen insufficiency disrupts cellular-signaling pathways and produces pathologic alterations in penile tissues, leading to erectile dysfunction. In this review, we discuss androgen-dependent cellular, molecular, and physiologic mechanisms modulating erectile function in the animal model, and the implication of this knowledge in testosterone use in the clinical setting to treat erectile dysfunction. The new clinical paradigm incorporates many of the consensed points of view discussed in traditional consensed algorithms exclusively designed for men with androgen insufficiency. There are, however, novel and innovative differences with this new clinical paradigm. This paradigm represents a fresh effort to provide mandatory and optional management strategies for men with both androgen insufficiency and erectile dysfunction.

CONCLUSIONS

The new clinical paradigm is evidence-based and represents one of the first attempts to address a logical management plan for men with concomitant hormonal and sexual health concerns.

Regulation of adenosine 5',monophosphate-activated protein kinase and lipogenesis by androgens contributes to visceral obesity in an estrogen-deficient state

Menopause is associated with an accumulation of visceral fat. An emerging concept suggests that relatively elevated levels of circulating androgens, compared with estrogens in postmenopausal women, underlie this shift in body fat distribution. In this study we administered dihydrotestosterone (DHT) to ovariectomized mice to examine the effect of relative androgen excess on adipose tissue distribution and function in estrogen-deficient mice. Compared with controls, DHT-treated mice exhibited increased body weight and visceral fat mass associated with triglyceride accumulation. Phosphorylation of AMP-activated protein kinase (AMPK) and acetyl CoA carboxylase was significantly decreased by DHT in visceral fat. In 3T3-L1 cells, DHT decreased phosphorylation of AMPK in a dose-dependent manner. In addition, DHT increased the expression of lipogenic genes (fatty acid synthase, sterol regulatory element binding protein-2, and lipoprotein lipase) in visceral fat. These data provide the first in vivo evidence that an increased androgen to estrogen ratio can promote visceral fat accumulation by inhibiting AMPK activation and stimulating lipogenesis.

Effects of growth hormone and/or testosterone on very low density lipoprotein apolipoprotein B100 kinetics and plasma lipids in healthy elderly men: a randomised controlled trial

OBJECTIVE

To assess the effects of low dose recombinant growth hormone (GH), testosterone (T) and combined GH and T, on lipid profiles and very low density lipoprotein apolipoprotein B (VLDL apoB) metabolism.

DESIGN AND PATIENTS

Sixty-nine healthy elderly men (65-80 yr) were studied in a six month double-blind, placebo-controlled trial. Participants were randomised to placebo GH and placebo T (P), GH and placebo T (GH), T and placebo GH (T) or GH and T (GHT).

MEASUREMENTS

Plasma lipid profiles were assessed before treatment and at 6 months. VLDL apoB absolute secretion rate (ASR) and fractional catabolic rate (FCR) were measured in a subset of 21 men: P (n=5); GH (n=5); T (n=6); GHT (n=5), with an infusion of 1-(13)C leucine. Fat mass (FM) was measured by DEXA and intra-abdominal fat (IAF) by CT scan.

RESULTS

IGF-I levels increased in the GH and GHT (P<0.001) groups: testosterone increased in the T (P=0.029) and GHT (P=0.05) groups. There was no change in total cholesterol, LDL-cholesterol, HDL-cholesterol, triglycerides, apolipoprotein A-I, apolipoprotein B or lipoprotein(a) in the GH, GHT or T groups. In the subset of 21 men, IGF-I levels increased similarly with GH and GHT (P<0.01) but T levels increased only with T (P<0.03). FM and IAF decreased significantly only with GHT (P<0.01, P=0.01). Treatment with GH, T or GHT had no effect on VLDL apoB ASR or VLDL FCR.

CONCLUSION

Co-administration of GH and T in near physiological doses in healthy elderly men resulted in favourable changes in body composition without altering the plasma lipid profile or VLDL apoB metabolism.

Polycystic ovarian syndrome: the next cardiovascular dilemma in women?

All known risks for cardiovascular disease are increased in women with polycystic ovary syndrome, which features amenorrhea, hirsutism, and obesity. Epidemiologic studies in these patients and their families have revealed a familial predisposition not only to polycystic ovary syndrome, but also diabetes, hypertension, and cardiovascular disease. The heterogeneity of phenotypes (clinically and biochemically) leads to difficulty in achieving a precise diagnosis, defining a single underlying pathogenesis, and selecting a homogeneous population for much needed prospective studies. The authors believe that while insulin resistance plays and important role in some cases of polycystic ovarian syndrome, it is the overall milieu created by the co-existence of several cardiovascular risk factors in polycystic ovarian syndrome patients which could be an important target for preventative strategies and therapy.

Omental and subcutaneous adipose tissue steroid levels in obese men

We examined plasma and fat tissue sex steroid levels in a sample of 28 men aged 24.8-62.2 years (average BMI value of 46.3 +/- 12.7 kg/m(2)). Abdominal adipose tissue biopsies were obtained during general or obesity surgery. Omental and subcutaneous adipose tissue steroid levels were measured by gas chromatography and chemical ionization mass spectrometry after appropriate extraction procedures. BMI and waist circumference were negatively correlated with plasma testosterone (r = -0.49 and -0.50, respectively, p < 0.01) and dihydrotestosterone (r = -0.58 and -0.56, respectively, p < 0.01), and positively associated with estrone levels (r = 0.64 and 0.62, respectively, p < 0.001). Regional differences in adipose tissue steroid levels were observed for dihydrotestosterone (p < 0.005), androstenedione (p < 0.0001) and dehydroepiandrosterone levels (p < 0.05), which were all significantly more concentrated in omental versus subcutaneous fat. Positive significant associations were found between circulating level of a steroid and its concentration in omental and subcutaneous adipose tissue, for estrone (r = 0.72 and 0.57, respectively, p < 0.01), testosterone (r = 0.66 and 0.58, respectively, p < 0.01) and dihydrotestosterone (r = 0.58 and 0.45, respectively, p < 0.05). Positive correlations were observed between plasma dehydroepiandrosterone-sulfate and omental (r = 0.56, p < 0.01) as well as subcutaneous adipose tissue dehydroepiandrosterone level (r = 0.38, p = 0.05). Positive significant associations were found between omental adipocyte responsiveness to positive lipolytic stimuli (isoproterenol, dibutyryl cyclic AMP and forskolin) and plasma or omental fat tissue androgen levels. In conclusion, although plasma androgen or estrogen levels are strong correlates of adipose tissue steroid content both in the omental and subcutaneous fat depots, regional differences may be observed. Androgen concentration differences in omental versus subcutaneous adipose tissue suggest a depot-specific impact of these hormones on adipocyte function and metabolism.

Weapons of penile smooth muscle destruction: androgen deficiency promotes accumulation of adipocytes in the corpus cavernosum

In men with erectile dysfunction, venous leakage is a common condition among non-responders to medical management and is attributed to penile smooth muscle atrophy. Androgens play a role in regulating trabecular smooth muscle growth and function. Further, androgens stimulate differentiation of progenitor cells into smooth muscle cells and inhibit their differentiation into adipocytes. We postulate that androgens exert a direct effect on penile tissue to maintain erectile function, and that androgen deficiency produces metabolic and structural imbalances in the corpus cavernosum, resulting in venous leakage and erectile dysfunction. To date, research efforts on the mechanisms by which androgens regulate penile erectile physiology have mainly focused on investigating the role of the NO/cGMP pathway. However, androgen-dependent mechanisms that regulate tissue remodeling have been poorly defined. Characterization of the molecular and cellular mechanisms by which androgens regulate corpus cavernosum structural and functional integrity would provide significant gains in knowledge and understanding of an important pathogenic process. In this review, we discuss the potential role of androgen in maintaining differentiation of progenitor cells into smooth muscle lineage and inhibition of differentiation into adipocytes. Androgen deficiency promotes differentiation into adipogenic lineage, and accumulation of adipocytes in the corpus cavernosum may contribute to erectile dysfunction.

Expression and activity of steroid aldoketoreductases 1C in omental adipose tissue are positive correlates of adiposity in women

We examined expression and activity of steroid aldoketoreductase (AKR) 1C enzymes in adipose tissue in women. AKR1C1 (20alpha-hydroxysteroid dehydrogenase; 20alpha-HSD), AKR1C2 (3alpha-HSD-3), and AKR1C3 (17beta-HSD-5) are involved mainly in conversion of progesterone to 20alpha-hydroxyprogesterone and inactivation of dihydrotestosterone to 5alpha-androstane-3alpha,17beta-diol. Abdominal subcutaneous and omental adipose tissue biopsies were obtained during abdominal hysterectomies in seven women with low visceral adipose tissue (VAT) area and seven age- and total body fat mass-matched women with visceral obesity. Women with elevated VAT areas were characterized by significantly higher omental adipose tissue 20alpha-HSD and 3alpha-HSD-3 mRNA abundance compared with women with low VAT accumulations (1.4- and 1.6-fold differences, respectively; P < 0.05). Omental and subcutaneous adipose tissue 3alpha-HSD activities were significantly higher in women with high vs. low VAT areas (P < 0.05 for both comparisons). Total and visceral adiposities were positively associated with omental 20alpha-HSD mRNA level (r = 0.75, P < 0.003 for fat mass; r = 0.57, P < 0.04 for VAT area) and omental 3alpha-HSD-3 mRNA level (r = 0.68, P < 0.01 for fat mass; r = 0.74, P < 0.003 for VAT area). Enzyme activities in both depots were also positively correlated with adiposity measures. Omental adipose tissue enzyme expression and activity were positively associated with omental adipocyte size and LPL activity. In conclusion, mRNA abundance and activity of AKR1C enzymes in abdominal adipose tissue compartments are positive correlates of adiposity in women. Increased progesterone and/or dihydrotestosterone reduction in abdominal adipose tissue may impact locally on fat cell metabolism.

Effects of testosterone on fat cell lipolysis. Species differences and possible role in polycystic ovarian syndrome

Testosterone is a potent regulator of lipolysis by influencing catecholamine signal transduction in fat cells. Major species differences exist as regards the testosterone effect. In rodents testosterone increases beta-adrenergic receptor mediated signals to lipolysis at multiple steps in the lipolytic cascade. The sex hormone also increases alpha2-adrenoceptor antilipolytic signalling in hamster which unlike rat express this receptor in their fat cells. In humans the region of adipose tissue is critical. Visceral fat cell lipolysis is not responsive to testosterone but this sex hormone decreases catecholamine-induced lipolysis in subcutaneous fat cells due to inhibition of the expression of beta2-adrenoceptors and hormone sensitive lipase. In polycystic ovarian syndrome (PCOS), which is characterized as a hyperandrogenic state, the lipolytic effect of catecholamine is decreased in subcutaneous adipocytes due to low content of beta2-adrenoceptors and hormone sensitive lipase. It is possible that the increased testosterone levels are responsible for these abnormalities in catecholamine signal transduction in subcutaneous fat cells of PCOS women. However, in visceral fat cells of PCOS women catecholamine-induced lipolysis is enhanced which cannot be explained by testosterone.

Direct effects of sex steroid hormones on adipose tissues and obesity

Sex steroid hormones are involved in the metabolism, accumulation and distribution of adipose tissues. It is now known that oestrogen receptor, progesterone receptor and androgen receptor exist in adipose tissues, so their actions could be direct. Sex steroid hormones carry out their function in adipose tissues by both genomic and nongenomic mechanisms. In the genomic mechanism, the sex steroid hormone binds to its receptor and the steroid-receptor complex regulates the transcription of given genes. Leptin and lipoprotein lipase are two key proteins in adipose tissues that are regulated by transcriptional control with sex steroid hormones. In the nongenomic mechanism, the sex steroid hormone binds to its receptor in the plasma membrane, and second messengers are formed. This involves both the cAMP cascade and the phosphoinositide cascade. Activation of the cAMP cascade by sex steroid hormones would activate hormone-sensitive lipase leading to lipolysis in adipose tissues. In the phosphoinositide cascade, diacylglycerol and inositol 1,4,5-trisphosphate are formed as second messengers ultimately causing the activation of protein kinase C. Their activation appears to be involved in the control of preadipocyte proliferation and differentiation. In the presence of sex steroid hormones, a normal distribution of body fat exists, but with a decrease in sex steroid hormones, as occurs with ageing or gonadectomy, there is a tendency to increase central obesity, a major risk for cardiovascular disease, type 2 diabetes and certain cancers. Because sex steroid hormones regulate the amount and distribution of adipose tissues, they or adipose tissue-specific selective receptor modulators might be used to ameliorate obesity. In fact, hormone replacement therapy in postmenopausal women and testosterone replacement therapy in older men appear to reduce the degree of central obesity. However, these therapies have numerous side effects limiting their use, and selective receptor modulators of sex steroid hormones are needed that are more specific for adipose tissues with fewer side effects.

Effect of testosterone on lipolysis in human pre-adipocytes from different fat depots

AIM/HYPOTHESIS

Regional differences in lipolysis, with higher lipolytic activity in visceral than subcutaneous fat, are important for the development of insulin resistance and might be influenced by testosterone.

METHODS

We studied testosterone-regulated lipolysis and protein expression (by western blot) in fully differentiated pre-adipocytes from visceral (omental) and abdominal subcutaneous adipose tissue from 52 human subjects. These cells were isolated and cultured in a serum-free medium.

RESULTS

Testosterone caused a specific, time- and concentration-dependent 50% reduction of catecholamine-stimulated lipolysis in the subcutaneous depot. Half of the maximum effect occurred at 10 nmol/l. The inhibitory effect was due to the inability of beta-adrenoceptors and cyclic AMP to stimulate the protein kinase A, hormone-sensitive lipase complex. Testosterone caused a depot-specific 50% reduction of the protein expression of hormone-sensitive lipase and beta(2)-adrenoceptors in differentiated subcutaneous pre-adipocytes, but no change in beta(1)-adrenoceptors, protein kinase A subunits or perilipin expression. In contrast, testosterone had no effect on lipolysis or protein expression in the visceral depot. However, testosterone receptors were present in both depots, and the hormone inhibited adipocyte leptin secretion. Similar effects on lipolysis were observed with dihydrotestosterone.

CONCLUSIONS/INTERPRETATION

Testosterone in physiological concentrations causes a depot-specific reduction of catecholamine-stimulated lipolysis in subcutaneous fat cells, probably due to reduced protein expression of beta(2)-adrenoceptors and hormone-sensitive lipase. This could be an important pathogenic factor underlying regional differences in lipolysis and development of insulin resistance and hyperandrogenic polycystic ovary syndrome.

Effect of flutamide and metformin administered alone or in combination in dieting obese women with polycystic ovary syndrome

BACKGROUND

Hyperandrogenism, hyperinsulinaemia and obesity play a key and coordinating roles in the pathogenesis of polycystic ovary syndrome (PCOS), contributing in different ways to the clinical expression of the syndrome. Weight loss is beneficial, but the additional administration of insulin-lowering drugs, such as metformin, and antiandrogens may produce further benefits, due to their different spectrum of action. The effects of long-term metformin and flutamide, an antiandrogen drug, added alone or in combination with a low-calorie diet, on body weight and fat distribution, androgens, metabolic parameters and clinical status in obese women with PCOS were investigated.

METHODS

Forty obese women with PCOS were enrolled in the study. After a 1-month diet, according to single-blind design, the patients were allocated to treatment with placebo, metformin (850 mg/orally, twice daily), flutamide (250 mg/orally, twice daily) or metformin (850 mg/orally, twice daily) + flutamide (250 mg/orally, twice daily) for the following 6 months, while continuing hypocaloric dieting. At baseline and at the end of the study, sex hormone, SHBG, lipid, insulin and insulin sensitivity determinations were evaluated. At the same time, clinical parameters such as anthropometry, total (TAT), visceral (VAT) and subcutaneous (SAT) adipose tissue, hirsutism and menses were also measured.

RESULTS

We found that, in obese PCOS women, following a hypocaloric diet the addition of metformin, flutamide or the combined metformin + flutamide treatment had some specific additional favourable effects with respect to the low-calorie diet alone. In particular, flutamide treatment seemed to add a significant effect in decreasing visceral fat, androstenedione, DHEA-S, total and low density lipoprotein (LDL) cholesterol and in improving hirsutism. Conversely, metformin had significant benefits on the menstrual status. The two drugs showed an additive effect in reducing testosterone concentrations and a synergistic effect in increasing high density lipoprotein (HDL) cholesterol and SHBG levels. Improvement of insulin sensitivity and hyperinsulinaemia appeared to depend on hypocaloric diet, without any further significant effect of the pharmacological treatments, either alone or in combination.

CONCLUSIONS

We conclude that, in obese PCOS women, following a hypocaloric diet the addition of metformin, flutamide or the combined metformin + flutamide treatment appears to have a more favourable outcome on body fat distribution, androgens, lipids, hirsutism and menses. However, our data emphasize the dominant role of hypocaloric dieting in improving insulin resistance and hyperinsulinaemia. Therefore, this study provides a rationale for specifically targeting different therapeutical options for PCOS according to the required outcomes.

The Mechanisms of Androgen Effects on Body Composition: Mesenchymal Pluripotent Cell as the Target of Androgen Action

Testosterone supplementation increases muscle mass primarily by inducing muscle fiber hypertrophy; however, the mechanisms by which testosterone exerts its anabolic effects on the muscle are poorly understood. The prevalent view is that testosterone improves net muscle protein balance by stimulating muscle protein synthesis, decreasing muscle protein degradation, and improving the reutilization of amino acids. However, the muscle protein synthesis hypothesis does not adequately explain testosterone-induced changes in fat mass, myonuclear number, and satellite cell number. We postulate that testosterone promotes the commitment of pluripotent stem cells into the myogenic lineage and inhibits their differentiation into the adipogenic lineage. The hypothesis that the primary site of androgen action is the pluripotent stem cell provides a unifying explanation for the observed reciprocal effects of testosterone on muscle and fat mass.