Reduced production rates of testosterone and dihydrotestosterone in healthy men treated with rosiglitazone

17β-estradiol rescues the damage of thiazolidinedione on chicken Sertoli cell proliferation via adiponectin

Thiazolidinedione (TZD) is an oral anti-diabetic drug that exhibits some side effects on the male reproductive system by interfering with the steroidogenesis and androgenic activity and also shows anti-proliferative effect on several cell types. This study investigated the effect of TZD on immature chicken Sertoli cell (SC) proliferation and the potential mechanism by which 17β-estradiol regulated this process. Chicken SC viability was investigated under different treatment concentration and time of TZD. 17β-estradiol (0.001 μM, 24 h) was added to analyze its effects on TZD-mediated cell viability, cell metabolic activity, cell growth, cell cycle progression, reactive oxygen species (ROS) level, antioxidant enzyme activity, mitochondria activity, oxygen consumption rate, adenosine triphosphate (ATP) level, and mitochondrial respiratory chain enzyme activity, adiponectin expression and several cell proliferation-related genes mRNA and protein levels. We performed the microRNA (miRNA) array to find TZD-induced differentially expressed miRNAs and validated whether miR-1577 can target on adiponectin via the dual luciferase reporter assay, as well as verified the effect of adiponectin addition with different concentrations on the SC viability. Further, SCs were transfected with miR-1577 agomir (a double-stranded synthetic miRNA mimic) in the presence or absence of TZD and antagomir (a single-stranded synthetic miRNA inhibitor) in the presence or absence of 17β-estradiol to analyze whether miR-1577 was involved in TZD-mediated SC proliferation and whether 17β-estradiol regulated this process. Results showed that TZD significantly inhibited SC viability, cell metabolic activity, cell growth, and cell cycle progression, while increased adiponectin level and ROS generation. TZD-treated SCs presented decreases of antioxidant enzyme activity, mitochondria activity, basal and maximal respiration, ATP production and level, mitochondrial respiratory chain enzyme activity, and mRNA and protein expressions of several cell proliferation-related genes, as well as the significant alteration of miRNA expressions (a total number of 55 miRNAs were up-regulated whereas 53 miRNAs down-regulated). Whereas, 17β-estradiol played a positive role in chicken SC proliferation and rescued the damage of TZD on SC proliferation by up-regulating miR-1577 expression whose target gene was validated to be the adiponectin. In addition, exogenous adiponectin (more than 1 μg/ml) treatment exhibited a significant inhibition on the SC viability. Transfection of miR-1577 agomir promoted the SC proliferation via down-expressed adiponectin, and increased the mitochondrial function and cell proliferation-related gene expression, while TZD weakened the positive effect of miR-1577 agomir on SCs. On the other hand, transfection of miR-1577 antagomir inhibited SC proliferation by producing the opposite effects on above parameters, while 17β-estradiol attenuated the negative effect of miR-1577 antagomir on SCs. These findings suggest down-expressed miR-1577 is involved in the regulation of TZD-inhibited SC proliferation through increasing adiponectin level, and this damage of TZD on the immature chicken SC proliferation can be ameliorated by appropriate dose of exogenous 17β-estradiol treatment. This study provides an insight into the cytoprotective effect of 17β-estradiol on TZD-damaged SC proliferation and may suggest a potential strategy for reducing the risk of SC dysfunction caused by the abuse of TZD.

The probable mechanism of reduced androgen level in COVID-19 patients

COVID-19, caused by the SARS-CoV-2, has challenged the health care systems of the world. Although the pulmonary complications of the infection have received extensive attention, addressing the other complications (e.g., changes in androgen levels) could further provide a more efficient understanding of the disease, which might aid in combating it. Since the association between androgens and the expression and activity of SARS-CoV-2 receptors has been proven and anti-androgen-based therapies have been considered in this regard, addressing various aspects of androgen level changes can be constructive. The present paper examines the possible mechanisms of changes in androgen levels by the virus. It seems that the infection of the gonads by the SARS-CoV-2 could reduce the androgen levels by affecting different cellular pathways.

Can Antidiabetic Drugs Improve Male Reproductive (Dys)Function Associated with Diabetes?

The alarming increase in the number of diabetic patients worldwide raises concerns regarding the impact of the disease on global health, not to mention on social and economic aspects. Furthermore, the association of this complex metabolic disorder with male reproductive impairment is worrying, mainly due to the increasing chances that young individuals, at the apex of their reproductive window, could be affected by the disease, further contributing to the disturbing decline in male fertility worldwide. The cornerstone of diabetes management is glycemic control, proven to be effective in avoiding, minimizing or preventing the appearance or development of disease-related complications. Nonetheless, the possible impact of these therapeutic interventions on male reproductive function is essentially unexplored. To address this issue, we have made a critical assessment of the literature on the effects of several antidiabetic drugs on male reproductive function. While the crucial role of insulin is clear, as shown by the recovery of reproductive impairments in insulin-deficient individuals after treatment, the same clearly does not apply to other antidiabetic strategies. In fact, there is an abundance of controversial reports, possibly related to the various study designs, experimental models and compounds used, which include biguanides, sulfonylureas, meglitinides, thiazolidinediones/glitazones, bile acid sequestrants, amylin mimetics, as well as sodiumglucose co-transporter 2 (SGLT2) inhibitors, glucagon-like peptide 1 (GLP1), α-glucosidase inhibitors and dipeptidyl peptidase 4 (DPP4) inhibitors. These aspects constitute the focus of the current review.

Antidiabetic therapies and male reproductive function: where do we stand?

Diabetes mellitus has been increasing at alarming rates in recent years, thus jeopardizing human health worldwide. Several antidiabetic drugs have been introduced in the market to manage glycemic levels, and proven effective in avoiding, minimizing or preventing the appearance or development of diabetes mellitus-related complications. However, and despite the established association between such pathology and male reproductive dysfunction, the influence of these therapeutic interventions on such topics have been scarcely explored. Importantly, this pathology may contribute toward the global decline in male fertility, giving the increasing preponderance of diabetes mellitus in young men at their reproductive age. Therefore, it is mandatory that the reproductive health of diabetic individuals is maintained during the antidiabetic treatment. With this in mind, we have gathered the available information and made a critical analysis regarding the effects of several antidiabetic drugs on male reproductive function. Unlike insulin, which has a clear and fundamental role on male reproductive function, the other antidiabetic therapies' effects at this level seem incoherent. In fact, studies are highly controversial possibly due to the different experimental study approaches, which, in our opinion, suggests caution when it comes to prescribing such drugs to young diabetic patients. Overall, much is still to be determined and further studies are needed to clarify the safety of these antidiabetic strategies on male reproductive system. Aspects such as the effects of insulin levels variations, consequent of insulin therapy, as well as what will be the impact of the side effect hypoglycemia, common to several therapeutic strategies discussed, on the male reproductive system are still to be addressed.

Similar causes of various reproductive disorders in early life

During the past few decades, scientific evidence has been accumulated concerning the possible adverse effects of the exposure to environmental chemicals on the well-being of wildlife and human populations. One large and growing group of such compounds of anthropogenic or natural origin is referred to as endocrine-disrupting chemicals (EDCs), due to their deleterious action on the endocrine system. This concern was first focused on the control of reproductive function particularly in males, but has later been expanded to include all possible endocrine functions. The present review describes the underlying physiology behind the cascade of developmental events that occur during sexual differentiation of males and the specific role of androgen in the masculinization process and proper organogenesis of the external male genitalia. The impact of the genetic background, environmental exposures and lifestyle factors in the etiology of hypospadias, cryptorchidism and testicular cancer are reviewed and the possible role of EDCs in the development of these reproductive disorders is discussed critically. Finally, the possible direct and programming effects of exposures in utero to widely use therapeutic compounds, environmental estrogens and other chemicals on the incidence of reproductive abnormalities and poor semen quality in humans are also highlighted.

Adiposopathy: how do diet, exercise and weight loss drug therapies improve metabolic disease in overweight patients?

An increase in bodyweight is generally associated with an increased risk of excessive fat-related metabolic diseases (EFRMD), including Type 2 diabetes mellitus, hypertension and dyslipidemia. However, not all patients who are overweight have EFRMD, and not all patients with EFRMD are significantly overweight. The adipocentric paradigm provides the basis for a unifying, pathophysiological process whereby fat gain in susceptible patients leads to fat dysfunction ('sick fat'), and wherein pathological abnormalities in fat function (adiposopathy) are more directly related to the onset of EFRMD than increases in fat mass (adiposity) alone. But just as worsening fat function worsens EFRMD, improved fat function improves EFRMD. Peroxisome proliferator-activated receptor-gamma agonists increase the recruitment, proliferation and differentiation of preadipocytes ('healthy fat') and cause apoptosis of hypertrophic and dysfunctional (including visceral) adipocytes resulting in improved fat function and improved metabolic parameters associated with EFRMD. Weight loss interventions, such as a hypocaloric diet and physical exercise, in addition to agents such as orlistat, sibutramine and cannabinoid receptor antagonists, may have favorable effects upon fat storage (lipogenesis and fat distribution), nutrient metabolism (such as free fatty acids), favorable effects upon adipose tissue factors involved in metabolic processes and inflammation, and enhanced 'cross-talk' with other major organ systems. In some cases, weight loss therapeutic agents may even affect metabolic parameters and adipocyte function independently of weight loss alone, suggesting that the benefit of these agents in improving EFRMD may go beyond their efficacy in weight reduction. This review describes how adiposopathy interventions may affect fat function, and thus improve EFRMD.

Testosterone and insulin resistance in the metabolic syndrome and T2DM in men

Obesity, type 2 diabetes mellitus and the metabolic syndrome are major risk factors for cardiovascular disease. Studies have demonstrated an association between low levels of testosterone and the above insulin-resistant states, with a prevalence of hypogonadism of up to 50% in men with type 2 diabetes mellitus. Low levels of testosterone are also associated with an increased risk of all-cause and cardiovascular mortality. Hypogonadism and obesity share a bidirectional relationship as a result of the complex interplay between adipocytokines, proinflammatory cytokines and hypothalamic hormones that control the pituitary-testicular axis. Interventional studies have shown beneficial effects of testosterone on components of the metabolic syndrome, type 2 diabetes mellitus and other cardiovascular risk factors, including insulin resistance and high levels of cholesterol. Biochemical evidence indicates that testosterone is involved in promoting glucose utilization by stimulating glucose uptake, glycolysis and mitochondrial oxidative phosphorylation. Testosterone is also involved in lipid homeostasis in major insulin-responsive target tissues, such as liver, adipose tissue and skeletal muscle.

Effect of pioglitazone on testosterone in eugonadal men with type 2 diabetes mellitus: a randomized double-blind placebo-controlled study

OBJECTIVES

Pioglitazone is an insulin sensitizer used for the management of type 2 diabetes mellitus (T2DM). It has been shown to reduce testosterone level in patients with polycystic ovarian syndrome. However, its effect on testosterone in men has not been studied.

RESEARCH DESIGN AND METHODS

A randomized, double-blind, placebo-controlled trial with 6 months follow-up. Fifty (25 in each group) eugonadal men (well virilized and total testosterone ≥ 12 nm) with T2DM, aged 30-55 year and HbA1c of ≤ 7.5% were randomly assigned to receive pioglitazone 30 mg per day or placebo along with existing glimepiride and metformin therapy.

RESULTS

As compared to placebo, 6 months of pioglitazone therapy in patients with T2DM resulted in significant reduction in mean total testosterone level (16.1 to 14.9 vs 17.1 to 17.0 nm; P = 0.031), calculated free testosterone (P = 0.001) and bioavailable testosterone (P = 0.000) despite significant increase in sex hormone-binding globulin (P = 0.000). Plasma androstenedione (∆(4) ) level increased (1.5 to 1.9 vs 1.7 to 1.7 ng/ml; P = 0.051) following pioglitazone therapy. The decrease in testosterone was independent of change in body weight, body fat and HbA1c.

CONCLUSION

Pioglitazone therapy significantly decreases total, free and bioavailable testosterone in eugonadal men with T2DM. The effects of these alterations need to be determined by further long-term studies.

Production Rates of Cortisol in Obesity

OBJECTIVE

To determine the metabolic clearance rates (MCRs) and endogenous production rates (PRs) of cortisol (F) in grades 2 and 3 obese men (n = 9) and women (n = 6).

RESEARCH METHODS AND PROCEDURES

The MCRs and the endogenous PRs of cortisol (F) were determined in grades 2 and 3 obese men (n = 9) and women (n = 6) using the stable isotope dilution technique and mass spectrometry.

RESULTS

In obese women, endogenous PRs of F (0.6 +/- 0.4 mg/h) were similar to those of nonobese women, but MCRs of F were higher in obese women (9 +/- 4 L/h) compared with nonobese women (5 + 2 L/h; p < 0.05). The MCR of F was correlated with the ratio of excreted cortisone to F metabolites. Furthermore, obese women were characterized by an increased ratio of androsterone to etiocholanolone (p < 0.01). In obese men, the MCRs (11 +/- 6 L/h) and the endogenous PRs of F (0.6 +/- 0.3 mg/h) were both similar to those of nonobese men, but the MCR of F was directly correlated with the ratio of excreted cortisone to F metabolites (r = 0.7833, p = 0.012).

DISCUSSION

These data demonstrate sex-specific differences in F metabolism in obesity. The rise in MCRs of F is more pronounced in obese women than in men. However, the increase in the MCR of F is moderate in both genders and exceeds the normal range only in a subgroup of obese individuals.

Glucose ingestion acutely lowers pulsatile LH and basal testosterone secretion in men

Chronic hyperglycemia inhibits the male gonadal axis. The present analyses test the hypothesis that acute glucose ingestion also suppresses LH and testosterone (T) secretion and blunts the LH-T dose-response function. The design comprised a prospectively randomized crossover comparison of LH and T secretion after glucose vs. water ingestion in a Clinical Translational Research Center. The participants were healthy men (n = 57) aged 19-78 yr with body mass index (BMI) of 20-39 kg/m(2). The main outcome measurements were deconvolution and LH-T dose-response analyses of 10-min data. LH-T responses were regressed on glucose, insulin, leptin, adiponectin, age, BMI, and CT-estimated abdominal visceral fat. During the first 120 min after glucose ingestion, for each unit decrease in LH concentrations, T concentrations decreased by 86 (27-144) ng/dl (r = 0.853, P < 0.001). Based upon deconvolution analysis, glucose compared with water ingestion reduced 1) basal (nonpulsatile; P < 0.001) and total (P < 0.001) T secretion without affecting pulsatile T output and 2) pulsatile (P = 0.043) but not basal LH secretion. By multivariate analysis, pulsatile LH secretion positively predicted basal T secretion after glucose ingestion (r = 0.374, P = 0.0042). In addition, the glucose-induced fall in pulsatile LH secretion was exacerbated by higher fasting insulin concentrations (P = 0.054) and attenuated by higher adiponectin levels (P = 0.0037). There were no detectable changes in the analytically estimated LH-T dose-response curves (P > 0.30). In conclusion, glucose ingestion suppresses pulsatile LH and basal T secretion acutely in healthy men. Suppression is influenced by age, glucose, adiponectin, and insulin concentrations.

Effect of chronic treatment with Rosiglitazone on Leydig cell steroidogenesis in rats: in vivo and ex vivo studies

BACKGROUND

The present study was designed to examine the effect of chronic treatment with rosiglitazone - thiazolidinedione used in the treatment of type 2 diabetes mellitus for its insulin sensitizing effects - on the Leydig cell steroidogenic capacity and expression of the steroidogenic acute regulatory protein (StAR) and cholesterol side-chain cleavage enzyme (P450scc) in normal adult rats.

METHODS

Twelve adult male Wistar rats were treated with rosiglitazone (5 mg/kg) administered by gavage for 15 days. Twelve control animals were treated with the vehicle. The ability of rosiglitazone to directly affect the production of testosterone by Leydig cells ex vivo was evaluated using isolated Leydig cells from rosiglitazone-treated rats. Testosterone production was induced either by activators of the cAMP/PKA pathway (hCG and dbcAMP) or substrates of steroidogenesis [22(R)-hydroxy-cholesterol (22(R)-OH-C), which is a substrate for the P450scc enzyme, and pregnenolone, which is the product of the P450scc-catalyzed step]. Testosterone in plasma and in incubation medium was measured by radioimmunoassay. The StAR and P450scc expression was detected by immunocytochemistry.

RESULTS

The levels of total circulating testosterone were not altered by rosiglitazone treatment. A decrease in basal or induced testosterone production occurred in the Leydig cells of rosiglitazone-treated rats. The ultrastructural and immunocytochemical analysis of Leydig cells from rosiglitazone-treated rats revealed cells with characteristics of increased activity as well as increased StAR and P450scc expression, which are key proteins in androgen biosynthesis. However, a number of rosiglitazone-treated cells exhibited significant mitochondrial damage.

CONCLUSION

The results revealed that the Leydig cells from rosiglitazone-treated rats showed significant reduction in testosterone production under basal, hCG/dbcAMP- or 22 (R)-OH-C/pregnenolone-induced conditions, although increased labeling of StAR and P450scc was detected in these cells by immunocytochemistry. The ultrastructural study suggested that the lower levels of testosterone produced by these cells could be due to mitochondrial damage induced by rosiglitazone.

The effect of thiazolidinediones on bone mineral density in Chinese older patients with type 2 diabetes

The effect of thiazolidinediones (TZDs) on bone mineral density (BMD) and bone metabolism in patients with type 2 diabetes is still in debate. Accumulating evidence has emerged that long-term administration of TZDs may increase the occurrence of osteoporosis, at least in postmenopausal women. Because little clinical data has been reported on Chinese people, a retrospective study was performed. One-hundred ninety-eight Chinese people, all from our inpatients, were selected for a 24-28 month review (26 +/- 0.5 m). Four groups divided according to gender and TZD use were designated fTZD, mTZD, f and m. Changes of subjects' BMD and bone metabolism markers were noted and analyzed. Compared with group f, bone loss from fTZD in this over 24-month review was more significant in lumbar spine (L1-L4) (0.1 +/- 0.15 vs. 0.06 +/- 0.11) and right hip (0.09 +/- 0.15 vs. 0.05 +/- 0.14) (g/cm(3)) (P < 0.05). However, the opposite result was found in male patients with less bone loss in group mTZD. Two bone metabolism markers, including beta C-terminal telopeptide of type I collagen (beta-CTX) and osteocalcin (OC), in this study did not prove valuable in revealing changes among groups. We concluded that long-term TZD use may increase the risk of bone loss in Chinese postmenopausal patients with type 2 diabetes, which may provide caution on drug treatment in clinical practice. Whether TZD can protect male patients against BMD loss or not awaits further research.

Steroidogenesis in the fetal testis and its susceptibility to disruption by exogenous compounds

Masculinization depends on adequate production of testosterone by the fetal testis within a specific "masculinization programming window." Disorders resulting from subtle deficiencies in this process are common in humans, and environmental exposures/lifestyle could contribute causally because common therapeutic and environmental compounds can affect steroidogenesis. This evidence derives mainly from rodent studies, but because there are major species differences in regulation of steroidogenesis in the fetal testis, this may not always be a guide to potential effects in the human. In addition to direct study of the effects of compounds on steroidogenesis, information also derives from study of masculinization disorders that result from mutations in genes in pathways regulating steroidogenesis. This review addresses this issue by critically reviewing the comparative timing of production and regulation of steroidogenesis in the fetal testis of humans and of rodents and its susceptibility to disruption; where there is limited information for the fetus, evidence from effects on steroidogenesis in the adult testis is considered. There are a number of fundamental regulatory differences between the human and rodent fetal testis, most notably in the importance of paracrine vs. endocrine drives during masculinization such that inactivating LH receptor mutations block masculinization in humans but not in rodents. Other large differences involve the steroidogenic response to estrogens and GnRH analogs and possibly phthalates, whereas for other compounds there may be differences in sensitivity to disruption (ketoconazole). This comparison identifies steroidogenic targets that are either vulnerable (mitochondrial cholesterol transport, CYP11A, CYP17) or not (cholesterol uptake) to chemical interference.

Activation of PPARγ by Rosiglitazone does not negatively impact male sex steroid hormones in diabetic rats

Peroxisome proliferator-activated receptor gamma (PPARγ) activation decreased serum testosterone (T) in women with hyperthecosis and/or polycystic ovary syndrome and reduced the conversion of androgens to estradiol (E2) in female rats. This implies modulation of female sex steroid hormones by PPARγ. It is not clear if PPARγ modulates sex steroid hormones in diabetic males. Because PPARγ activation by thiazolidinedione increased insulin sensitivity in type 2 diabetes, understanding the long term impact of PPARγ activation on steroid sex hormones in males is critical. Our objective was to determine the effect of PPARγ activation on serum and intratesticular T, luteinizing hormone (LH), follicle stimulating hormone (FSH) and E2 concentrations in male Zucker diabetic fatty (ZDF) rats treated with the PPARγ agonist rosiglitazone (a thiazolidinedione). Treatment for eight weeks increased PPARγ mRNA and protein in the testis and elevated serum adiponectin, an adipokine marker for PPARγ activation. PPARγ activation did not alter serum or intratesticular T concentrations. In contrast, serum T level but not intratesticular T was reduced by diabetes. Neither diabetes nor PPARγ activation altered serum E2 or gonadotropins FSH and LH concentrations. The results suggest that activation of PPARγ by rosiglitazone has no negative impact on sex hormones in male ZDF rats.

Are the adverse effects of glitazones linked to induced testosterone deficiency?

Background

Adverse side-effects of the glitazones have been frequently reported in both clinical and animal studies, especially with rosiglitazone (RGZ) and pioglitazone (PGZ), including congestive heart failure, osteoporosis, weight gain, oedema and anaemia. These led to consideration of an evidence-based hypothesis which would explain these diverse effects, and further suggested novel approaches by which this hypothesis could be tested.

Presentation of hypothesis

The literature on the clinical, metabolic and endocrine effects of glitazones in relation to the reported actions of testosterone in diabetes, metabolic syndrome, and cardiovascular disease is reviewed, and the following unifying hypothesis advanced: "Glitazones induce androgen deficiency in patients with Type 2 Diabetes Mellitus resulting in pathophysiological changes in multiple tissues and organs which may explain their observed clinical adverse effects." This also provides further evidence for the lipocentric concept of diabetes and its clinical implications.

Testing of the hypothesis

Clinical studies to investigate the endocrine profiles, including measurements of TT, DHT, SHBG, FT and estradiol, together with LH and FSH, in both men and women with T2DM before and after RGZ and PGZ treatment in placebo controlled groups, are necessary to provide data to substantiate this hypothesis. Also, studies on T treatment in diabetic men would further establish if the adverse effects of glitazones could be reversed or ameliorated by androgen therapy. Basic sciences investigations on the inhibition of androgen biosynthesis by glitazones are also warranted.

Implications of the hypothesis

Glitazones reduce androgen biosynthesis, increase their binding to SHBG, and attenuate androgen receptor activation, thus reducing the physiological actions of testosterone, causing relative and absolute androgen deficiency. This hypothesis explains the adverse effects of glitazones on the heart and other organs resulting from reversal of the action of androgens in directing the maturation of stem cells towards muscle, vascular endothelium, erythroid stem cells and osteoblasts, and away from adipocyte differentiation. The higher incidence of side-effects with RGZ than PGZ, may be explained by a detailed study of the mechanism by which glitazones down-regulate androgen biosynthesis and action, resulting in a state of androgen deficiency.

Impact of diisobutyl phthalate and other PPAR agonists on steroidogenesis and plasma insulin and leptin levels in fetal rats

Endocrine disrupting chemicals can induce malformations and impairment of reproductive function in experimental animals and may have similar effects in humans. Recently, the environmental obesogen hypothesis was proposed, suggesting that environmental chemicals contribute to the development of obesity and insulin resistance. These effects could be related to chemical interaction with nuclear receptors such as the peroxisome proliferator activated receptors (PPARs). As several testosterone-reducing drugs are PPAR activators, we aimed to examine whether four PPAR agonists were able to affect fetal testosterone production and masculinization of rats. Additionally, we wished to examine whether these chemicals affected fetal plasma levels of insulin and leptin, which play important roles in the developmental programming of the metabolic system. Pregnant Wistar rats were exposed from gestation day (GD) 7-21 to diisobutyl phthalate (DiBP), butylparaben, perfluorooctanoate, or rosiglitazone (600, 100, 20, or 1 mg/kg bw/day, respectively). Endocrine endpoints were studied in offspring at GD 19 or 21. DiBP, butylparaben and rosiglitazone reduced plasma leptin levels in male and female offspring. DiBP and rosiglitazone additionally reduced fetal plasma insulin levels. In males, DiBP reduced anogenital distance, testosterone production and testicular expression of Insl-3 and genes related to steroidogenesis. PPARalpha mRNA levels were reduced by DiBP at GD 19 in testis and liver. In females, DiBP increased anogenital distance and increased ovarian aromatase mRNA levels. This study reveals new targets for phthalates and parabens in fetal male and female rats and contributes to the increasing concern about adverse effects of human exposure to these compounds.

Impact of metformin and rosiglitazone treatment on glucose transporter 4 mRNA expression in women with polycystic ovary syndrome

OBJECTIVE

The insulin-resistant state of the polycystic ovary syndrome (PCOS) was found to be associated with a decreased glucose transporter GLUT4 expression in the insulin target tissues. This study was performed to explore whether the well-known clinical, hormonal and metabolic efficacy of metformin or rosiglitazone treatment is reflected in the modulation of adipocyte GLUT4 mRNA expression in patients with PCOS.

METHODS

We enrolled 35 women with PCOS. They received either metformin or rosiglitazone for 6 months. A history, blood samples for the measurement of androgens and s.c. adipose tissue samples were taken at baseline and end point. Quantification of GLUT4 mRNA expression in adipose tissue was performed using real-time quantitative PCR. Homeostasis model assessment (HOMA(IR)) score calculation was applied as a measure for insulin resistance (IR).

RESULTS

GLUT4 mRNA expression in adipose tissue increased significantly in both groups (P<0.001). The increase was more pronounced in the rosiglitazone group (P=0.040). There was a statistically significant improvement of HOMA(IR) in both groups (P=0.008). After treatment, frequencies of menstrual bleeding were significantly higher (P<0.001) and serum total testosterone levels significantly lower in both groups (P=0.001).

CONCLUSIONS

A 6-month therapy with insulin sensitizers resulted in marked improvement in adipose tissue GLUT4 mRNA expression in PCOS patients, rosiglitazone being more effective when compared with metformin. The augmentation of the insulin signal transduction was accompanied by a significant improvement of HOMA(IR), menstrual pattern and androgen profile.

Decreased androgen levels and improved menstrual pattern after angiotensin II receptor antagonist telmisartan treatment in four hypertensive patients with polycystic ovary syndrome: case series

We describe 4 consecutive hypertensive women with polycystic ovary syndrome, classified according to the National Institute of Child Health and Human Development (NICHD) criteria, treated with telmisartan 40 mg/d for six months. Blood pressure, menstrual pattern, body mass index (BMI), homeostasis model assessment of insulin resistance, testosterone, dehydroepiandrosterone sulfate (DHEAS), and androstenedione were recorded and measured before and after telmisartan treatment. Obese hypertensive polycystic ovary syndrome patients had a decrease in systolic blood pressure. Marked drop-off in serum androgen concentrations was observed in all four patients. Three patients improved their menstrual cyclicity. The improvements were independent of changes in weight. The reduction of androgen concentrations and improvement in menstrual pattern was achieved despite a non-significant change of fasting insulin levels in patients, who were not considered severely insulin resistant at baseline. These findings may provide a new basis for a proper choice of the antihypertensive drug in hypertensive women with polycystic ovary syndrome.

Anterior pituitary hormone replacement therapy--a clinical review

This clinical review summarizes current approaches to diagnosis and treatment of anterior pituitary hormone deficiency. The diagnostic value of endocrine function tests and replacement strategies for hydrocortisone, thyroxine, sex steroids, and growth hormone replacement are reviewed. Female androgen deficiency syndrome and the current role of DHEA and testosterone replacement in women are also discussed.

Genetic variants in peroxisome proliferator-activated receptor gamma influence insulin resistance and testosterone levels in normal women, but not those with polycystic ovary syndrome

OBJECTIVE

To investigate the relationship of the peroxisome proliferator-activated receptor gamma (PPARG) Pro12Ala and silent exon 6 (His447His) polymorphisms with the clinical features of polycystic ovary syndrome (PCOS).

DESIGN

Patients with PCOS and control subjects were genotyped for Pro12Ala and His447His. Associations between genotype, diagnosis, and hormonal/metabolic parameters were assessed.

SETTING

Subjects were recruited from the reproductive endocrinology clinic at the University of Alabama at Birmingham, Birmingham, Alabama. Control subjects were recruited from the surrounding community. Genotyping was performed at the Cedars-Sinai Medical Center in Los Angeles, California.

PATIENT(S)

Participants included 285 white women with PCOS and 187 controls.

INTERVENTION(S)

None.

MAIN OUTCOME MEASURE(S)

The Pro12Ala and His447His genotypes, and hormonal and metabolic phenotypes.

RESULT(S)

The Pro12Ala and His447His genotypes did not influence risk of PCOS or its component phenotypes in patients with PCOS. In controls, Pro12Ala did not influence measures of insulin resistance or androgen production. However, carriers of the His447His T-allele had significantly decreased free and total T levels, and a significantly decreased homeostasis model assessment index of insulin resistance. Furthermore, haplotypes in controls bearing the His447His T-allele were also associated with decreased T.

CONCLUSION(S)

Peroxisome proliferator-activated receptor gamma does not appear to be an important modifier gene in PCOS. In controls, however, the His447His T-allele may be in linkage disequilibrium with a functional variant that influences insulin resistance and T production.

Thiazolidinedione use and bone loss in older diabetic adults

CONTEXT

Activation of peroxisome proliferator-activated receptor-gamma by thiazolidinediones (TZDs) results in lower bone mass in mice.

OBJECTIVE

The objective of the study was to determine whether TZD use is associated with changes in bone mineral density (BMD) in older adults with type 2 diabetes.

DESIGN

We analyzed 4-yr follow-up data from the Health, Aging, and Body Composition observational study.

SETTING

The study was conducted in a general community.

PATIENTS

White and black, physically able men and women, aged 70-79 yr at baseline with diabetes defined by self-report, use of hypoglycemic medication, elevated fasting glucose (>/=126 mg/dl), or elevated 2-h glucose tolerance test (>/=200 mg/dl) participated in the study.

MAIN OUTCOME MEASURES

Whole-body, lumbar spine (derived from whole body), and hip BMD were measured by dual-energy x-ray absorptiometry at 2-yr intervals.

RESULTS

Of 666 diabetic participants, 69 reported TZD use at an annual visit, including troglitazone (n = 22), pioglitazone (n = 30), and/or rosiglitazone (n = 31). Those with TZD use had higher baseline hemoglobin A(1c) and less weight loss over 4 yr but similar baseline BMD and weight than others with diabetes. In repeated-measures models adjusted for potential confounders associated with TZD use and BMD, each year of TZD use was associated with greater bone loss at the whole body [additional loss of -0.61% per year; 95% confidence interval (CI) -1.02, -0.21% per year], lumbar spine (-1.23% per year; 95% CI -2.06, -0.40% per year), and trochanter (-0.65% per year; 95% CI -1.18, -0.12% per year) in women, but not men, with diabetes.

CONCLUSION

These observational results suggest that TZDs may cause bone loss in older women. These results need to be tested in a randomized trial.

Mechanisms underlying the anti-androgenic effects of diethylhexyl phthalate in fetal rat testis

Diethylhexyl phthalate (DEHP) is widely used as a plasticizer in consumer products and is known to disturb the development of the male reproductive system in rats. The mechanisms by which DEHP exerts these effects are not yet fully elucidated, though some of the effects are related to reduced fetal testosterone production. The present study investigated the effects of four different doses of DEHP on fetal testicular histopathology, testosterone production and expression of proteins and genes involved in steroid synthesis in fetal testes. Pregnant Wistar rats were gavaged from GD 7 to 21 with vehicle, 10, 30, 100 or 300 mg/kg bw/day of DEHP. In male fetuses examined at GD 21, testicular testosterone production ex vivo and testicular testosterone levels were reduced significantly at the highest dose. Histopathological effects on gonocytes were observed at 100 and 300 mg/kg bw/day, whereas Leydig cell effects were mainly seen at 300 mg/kg bw/day. Quantitative RT-PCR revealed reduced testicular mRNA expression of the steroidogenesis related factors SR-B1, StAR, PBR and P450scc. Additionally, we observed reduced mRNA expression of the nuclear receptor SF-1, which regulates certain steps in steroid synthesis, and reduced expression of the cryptorchidism-associated Insl-3. Immunohistochemistry showed clear reductions of StAR, PBR, P450scc and PPARgamma protein levels in fetal Leydig cells, indicating that DEHP affects regulation of certain steps in cholesterol transport and steroid synthesis. The suppression of testosterone levels observed in phthalate-exposed fetal rats was likely caused by the low expression of these receptors and enzymes involved in steroidogenesis. It is conceivable that the observed effects of DEHP on the expression of nuclear receptors SF-1 and PPARgamma are involved in the downregulation of steroidogenic factors and testosterone levels and thereby underlie the disturbed development of the male reproductive system.

Glucagon-like peptide-1 reduces the pulsatile component of testosterone secretion in healthy males

BACKGROUND

Glucagon-like-peptide-1 (7-36) amide (GLP-1), a potent regulator of glucose homeostasis, has been implicated in the control of hypothalamic-pituitary function. In vivo it is a relevant neuroendocrine modulator of gonadotropin-releasing hormone release, suggesting its possible role as a metabolic signal to the reproductive system. The present study was undertaken to establish its effect on luteinizing hormone (LH) and testosterone secretion in nine healthy male volunteers.

MATERIALS AND METHODS

Each subject underwent an oral glucose tolerance test to establish LH, testosterone, and GLP-1 responses to glucose. Euglycaemic clamp experiments (6 h) were performed on two occasions with saline or with a constant infusion of GLP-1 (0.4 pmol kg(-1) min (-1)). Blood samples were drawn at 10-min intervals to measure the pulsatile pattern of LH and testosterone secretion.

RESULTS

Ingestion of oral glucose resulted in a reduction in plasma testosterone levels at 30 min compared with baseline (P < 0.004) despite unaltered LH levels (P = 0.5). Constant GLP-1 infusion resulted in no change in LH (P = 0.83), testosterone (P = 0.96), follicle stimulating hormone (FSH) (P = 0.86) and leptin levels (P = 0.3). Pulse analysis revealed no significant difference in the number (P = 0.1) or median absolute amplitude (P = 0.3) of the LH pulses. However, there was a significant decrease in the number (3.0 +/- 0.6 vs. 1.3 +/- 0.4; P < 0.05) and a tendency for increased duration of testosterone pulses (97.4 +/- 16.7 vs. 170 +/- 27.1 min; P = 0.06).

CONCLUSION

Oral glucose ingestion and intravenous GLP-1 infusion reduce the pulsatile component of testosterone secretion by a mechanism independent of LH release.

Production rates of cortisol in men with hypogonadism

Healthy men have a larger endogenous cortisol production rate (PR) than healthy women. To investigate whether this sex-specific difference is maintained in men with low serum testosterone concentrations the endogenous PRs (2 pm to 6 pm) of testosterone, dihydrotestosterone (DHT), and cortisol were simultaneously determined in 10 hypogonadal men. As expected, hypogonadal men were characterized by subnormal PRs of testosterone (19.6 +/- 5.7 microg/h; normal, 180 to 346 microg/h) and of DHT (1.6 +/- 1.1 microg/h; normal, 11 to 20 microg/h). In hypogonadal patients with an intact pituitary-adrenal axis (n = 8), plasma concentrations (7.3 +/- 1.8 microg/dL), metabolic clearance rates (MCRs) (10.0 +/- 4.6 L/h), and endogenous PRs (0.6 +/- 0.2 mg/h) of cortisol were comparable to those seen in eugonadal men. Hence, the sex-specific difference in endogenous cortisol PRs does not depend on the prevailing serum concentrations and on the endogenous PRs of testosterone.

Changes in sex hormone-binding globulin and testosterone during weight loss and weight maintenance in abdominally obese men with the metabolic syndrome

BACKGROUND

Mild hypoandrogenism in men, usually defined by low levels of testosterone, is a peculiar feature of abdominal obesity that independently predicts the development of insulin resistance and diabetes mellitus. Little is known about the short- and long-term effects of weight loss on sex steroids in abdominally obese men, however.

OBJECTIVES

We assessed the effect of rapid weight loss and sustained weight maintenance on the plasma concentrations of testosterone and other sex hormones in 58 abdominally obese men (age, 46.3 +/- 7.5 years; body mass index, 36.1 +/- 3.8 kg/m(2); waist girth, 121 +/- 10 cm) with the metabolic syndrome.

RESULTS

The men lost on average 16.3 +/- 4.5 kg during a 9-week very low-calorie diet (VLCD) and maintained 14.3 +/- 9.1 kg weight loss after a 12-month maintenance period (vs. baseline, p < 0.001). Sex hormone-binding globulin (SHBG) increased from 27.6 +/- 11.9 to 48.1 +/- 23.5 nmol/l during the VLCD but decreased to 32.6 +/- 12.9 nmol/l during weight maintenance, which was still higher than at baseline (p < 0.001). Free testosterone (fT) increased from 185 +/- 66 to 208 +/- 70 pmol/l (p = 0.002) during the VLCD and remained high after 1 year of weight maintenance (212 +/- 84 pmol/l, p = 0.002). Total testosterone levels followed a pattern intermediate between fT and SHBG. Plasma estradiol and dehydroepiandrosterone sulphate concentrations changed only transiently or not at all.

CONCLUSIONS

Rapid weight loss with successful weight maintenance in abdominally obese men with the metabolic syndrome brings about a sustained increase in fT levels. The dramatic increase in SHBG attenuated initially during weight maintenance but remained elevated. These findings may be important with regard to prevention of progressive metabolic decompensation and cardiovascular disease associated with obesity and the metabolic syndrome.

Testosterone release rate and duration of action of testosterone pellet implants

OBJECTIVE

Testosterone pellets are a highly effective subdermal depot administered at regular intervals with the timing individualized depending upon return of the patient's characteristic androgen deficiency symptoms. Yet the in vivo testosterone release rate and effective duration of action of these pellets has been little studied systematically.

DESIGN

Analysis of prospectively collected data from three randomized controlled clinical trials. Collection of extruded pellets.

PATIENTS

Androgen-deficient men (n = 136) undergoing long-term androgen replacement therapy with a standard dose (800 mg) of testosterone pellets implanted subdermally at intervals from 5 to 7 months.

MEASUREMENTS

Testosterone release rate of pellets, consisting of pure crystalline testosterone without excipients, is estimated by measuring the dry weight lost by pellets (n = 179) over their time in situ. The effective duration of the standard regimen, and the influence of extrusion and patient or procedural characteristics on it, was estimated by timing of return for re-implantation due to recurrence of the patient's familiar androgen deficiency symptoms.

RESULTS

The loss of dry weight of intact (n = 112) pellets was strongly correlated with time in situ (r2 = 0.969) providing an estimate of daily testosterone release rate per 200 mg pellet of 1.34 +/- 0.02 mg/pellet/day (95% CI 1.30-1.37 mg/day) for the first 3 months. After 756 implantations of the standard dose, men return for re-implantation at 5.8 calendar months following no or only a single pellet extrusion, but the time to return was significantly shorter after multiple extrusions. No patient or procedural features influenced the timing of return. Among men with primary hypogonadism, increases in plasma LH and FSH were more sensitive than plasma total or free testosterone to changes in testosterone delivery following an extrusion.

CONCLUSION

Testosterone pellet implants release testosterone at a steady rate of 1.3 mg/200 mg implant/day (95% CI). The duration of action is about 6 months in an uncomplicated cycle with timing of return shortened by extrusions only in the 3.6% of procedures followed by multiple extrusions. No other patient or procedural features influenced duration of action. Among men with an intact hypothalamo-pituitary unit, plasma gonadotropins are more sensitive than blood total or free testosterone to reduced testosterone delivery following an extrusion.