Suppression of serum dehydroepiandrosterone sulfate levels by insulin: an evaluation of possible mechanisms

Correlation between Expression of Glucose Transporters in Granulosa Cells and Oocyte Quality in Women with Polycystic Ovary Syndrome

BACKGROUND

The glucose transporters (GLUTs) exhibit different tissue-specific expression. This study aimed to investigate the types of GLUTs expressed in human granulosa cells (GCs) obtained from women with polycystic ovary syndrome (PCOS) and their relationship with insulin resistance (IR) and the outcomes of in vitro maturation (IVM) of immature oocytes.

METHODS

Expression of GLUTs was evaluated in GCs from women with PCOS with or without IR. Thirty-six women with PCOS undergoing an IVM program were included. Differential gene expression between the insulin sensitive (IS) and IR group was measured by reverse transcription polymerase chain reaction.

RESULTS

Expression of GLUTs 1, 3, 5, 8, and 13 was constitutive, whereas expression of GLUTs 2 and 7 was not observed in human GCs. The remaining GLUTs, 4, 6, 9, 10, 11, and 12, were differentially expressed among patients according to metabolic status, such as insulin sensitivity. A higher number of GCs from patients with IR (92%) expressed GLUT6 than GCs from IS PCOS patients (46.3%). Logistic regression showed that expression of GLUTs 9, 11, and 12 correlates with rates of IVM at 48 hours, fertilization, and implantation, respectively.

CONCLUSION

This is the first report describing the expression pattern of all 13 members of the GLUT family in human GCs. Results of the present study suggest that patients' insulin sensitivity regulates GLUT expression in GCs in PCOS patients, and this may control oocyte quality for IVM and subsequent processes such as fertilization and implantation in patients taking part in an in vitro fertilization program.

Insulin resistance and the polycystic ovary syndrome revisited: an update on mechanisms and implications

Polycystic ovary syndrome (PCOS) is now recognized as an important metabolic as well as reproductive disorder conferring substantially increased risk for type 2 diabetes. Affected women have marked insulin resistance, independent of obesity. This article summarizes the state of the science since we last reviewed the field in the Endocrine Reviews in 1997. There is general agreement that obese women with PCOS are insulin resistant, but some groups of lean affected women may have normal insulin sensitivity. There is a post-binding defect in receptor signaling likely due to increased receptor and insulin receptor substrate-1 serine phosphorylation that selectively affects metabolic but not mitogenic pathways in classic insulin target tissues and in the ovary. Constitutive activation of serine kinases in the MAPK-ERK pathway may contribute to resistance to insulin's metabolic actions in skeletal muscle. Insulin functions as a co-gonadotropin through its cognate receptor to modulate ovarian steroidogenesis. Genetic disruption of insulin signaling in the brain has indicated that this pathway is important for ovulation and body weight regulation. These insights have been directly translated into a novel therapy for PCOS with insulin-sensitizing drugs. Furthermore, androgens contribute to insulin resistance in PCOS. PCOS may also have developmental origins due to androgen exposure at critical periods or to intrauterine growth restriction. PCOS is a complex genetic disease, and first-degree relatives have reproductive and metabolic phenotypes. Several PCOS genetic susceptibility loci have been mapped and replicated. Some of the same susceptibility genes contribute to disease risk in Chinese and European PCOS populations, suggesting that PCOS is an ancient trait.

Appetite and endocrine regulators of energy balance after 2 days of energy restriction: insulin, leptin, ghrelin, and DHEA-S

Using a double-blind, placebo-controlled crossover design, the effects of 48 h near complete energy restriction on endocrine regulators of appetite and satiety were assessed. Twelve men and one woman participated in this controlled, 2-day diet intervention study. One experimental trial was completed in a calorie deprived state (CAL-DEP; <10% of estimated energy requirements) and others in a fed condition (carbohydrate only and carbohydrate and fat; data were pooled and compared to CAL-DEP). Test meals containing prescribed energy intake and indistinguishable in sensory characteristics were provided during each trial. Glucose, insulin, leptin, ghrelin, cortisol, dehydroepiandrosterone-sulfate (DHEA-S), and satiety were repeatedly assessed. Mean glucose, insulin, and leptin concentrations were lower (P < 0.0001) for CAL-DEP compared to the fully fed (FED) state. Ghrelin and DHEA-S were higher (P < 0.0001) for CAL-DEP relative to FED. Cortisol levels declined each day regardless of diet (P < 0.0001) but were 32% higher (P < 0.01) at the conclusion of the session for CAL-DEP compared to FED. Satiety was 25% lower (P < 0.0001) for CAL-DEP relative to FED and decreased (P < 0.0001) over time regardless of diet. In the FED state, insulin (r = 0.55), glucose (r = 0.76), cortisol (r = -0.59), and DHEA-S (r = -0.62) were associated (P < 0.05) with satiety, but not during CAL-DEP. These findings show that 2 days of severe energy restriction alter several endocrine regulators of appetite independent of perception of increased hunger suggesting a physiological mechanism to explain overeating following acute periods of severe energy restriction.

Lower circulating levels of dehydroepiandrosterone, independent of insulin resistance, is an important determinant of severity of non-alcoholic steatohepatitis in Japanese patients

AIM

  The biological basis of variability in histological progression of non-alcoholic fatty liver disease (NAFLD) remains unknown. Dehydroepiandrosterone (DHEA), the most abundant steroid hormone, has been shown to influence sensitivity to reactive oxygen species, insulin sensitivity and expression of peroxisome proliferator-activated receptor-α. Our aim was to determine whether more histologically advanced NAFLD is associated with low circulating levels of DHEA in Japanese patients.

METHODS

  Serum samples were obtained in 133 Japanese patients with biopsy-proven NAFLD and in 399 sex- and age-matched healthy people undergoing health checkups. Serum levels of sulfated DHEA (DHEA-S) were measured by chemiluminescent enzyme immunoassay.

RESULTS

  Serum DHEA-S levels in NAFLD patients were similar to those in the control group. Of 133 patients, 90 patients were diagnosed as non-alcoholic steatohepatitis (NASH): 73 patients had stage 0-2, and 17 had stage 3 or 4. Patients with advanced NAFLD (NASH with fibrosis stage 3 or 4) had lower plasma levels of DHEA-S than patients with mild NAFLD (simple steatosis or NASH with fibrosis stage 0-2). The area under the receiver operating characteristic curve for DHEA in separating patients with and without advanced fibrosis was 0.788. A "dose effect" of lower DHEA-S and incremental fibrosis stage was observed with a mean DHEA-S of 170.4 ± 129.2, 137.6 ± 110.5, 96.2 ± 79.3, 61.2 ± 46.3 and 30.0 ± 32.0 µg/dL for fibrosis stages 0, 1, 2, 3, and 4, respectively. The association between DHEA-S and severity of NAFLD persisted after adjusting for age, sex and insulin resistance.

CONCLUSION

  Low circulating DHEA-S might have a role in the development of advanced NASH.

Insulin-stimulated release of D-chiro-inositol-containing inositolphosphoglycan mediator correlates with insulin sensitivity in women with polycystic ovary syndrome

Some actions of insulin are mediated by inositolphosphoglycan (IPG) mediators. Deficient release of a putative D-chiro-inositol-containing (DCI) IPG mediator may contribute to insulin resistance in women with polycystic ovary syndrome (PCOS). Previously, we demonstrated that oral DCI supplementation improved ovulation and metabolic parameters in women with PCOS. However, whether oral DCI mediates an increase in the release of the DCI-IPG mediator and an improvement in insulin sensitivity in women with PCOS is unknown. We conducted a randomized controlled trial of DCI supplementation vs placebo in 11 women with PCOS who were assessed at 2 time points 6 weeks apart. Plasma DCI, DCI-IPG release during oral glucose tolerance test (AUC(DCI-IPG)), and insulin sensitivity (S(i)) by frequently sampled intravenous glucose tolerance test were assessed at baseline and end of study. The study was terminated early because of a sudden unavailability of the study drug. However, in all subjects without regard to treatment assignment, there was a positive correlation between the change in AUC(DCI-IPG)/AUC(insulin) ratio and the change in S(i) during the 6-week period (r = 0.69, P = .02), which remained significant after adjustment for body mass index (P = .022) and after further adjustment for body mass index and treatment allocation (P = .0261). This suggests that, in women with PCOS, increased glucose-stimulated DCI-IPG release is significantly correlated with improved insulin sensitivity. The significant relationship between DCI-IPG release and insulin sensitivity suggests that the DCI-IPG mediator may be a target for therapeutic interventions in PCOS.

Adrenarche and the evolution of human life history

Adrenarche, the prepubertal onset of adrenal production of dehydroepiandrosterone sulfate (DHEAS), is a distinctive aspect of the human life course. Yet its evolutionary origins remain unexplained. Production of DHEAS is associated with the development of the zona reticularis, a novel histological layer within the adrenal gland, derived from the fetal adrenal gland, and associated with primates more generally. Evidence that DHEAS is a neurosteroid, together with the fact that increases in DHEAS parallel patterns of cortical maturation from approximately age 6 years to the mid-20s, suggests that DHEAS may play an important role in extended brain maturation among humans. DHEAS has demonstrated effects on mood in humans, and acts at neuron receptor sites. I suggest three ways in which DHEAS may play a role in human brain maturation: 1) increasing activity of the amgydala; 2) increasing activity of the hippocampus; and 3) promoting synaptogenesis within the cortex. I propose that associated changes in fearfulness and anxiety, and memory, could act to increase social interaction with nonfamiliar individuals and shape cognitive development. Comparison with the African apes suggests that the timing of adrenarche in chimpanzees may be similar to that in humans, though the full course of age-related changes in DHEAS and their relationship to reproductive and brain maturation are not clear. The role of DHEAS as a physiological mechanism supporting increased brain development, extended life span, and decreased sexual dimorphism is most compatible with Kaplan et al.'s (2000) theory of the evolution of human life history and intergenerational transfers.

Assessment of insulin resistance in the idiopathic hirsutism

BACKGROUND

Idiopathic hirsutism (IH) is the second most common cause of hirsutism, after polycystic ovary syndrome and occurs in about 15% of hirsute women. There are not many studies showing whether patients with IH also have insulin resistance. In the present study, we aimed to investigate the insulin sensivity in IH with non-obese and changing hormone levels during the hyperinsulinemic-euglycemic clamp.

METHODS

Twenty (20) non-obese women with IH (Group I) ranging in age from 20 to 30 (mean 25 +/- 5) years were studied. Hirsutism in women with normal testosterone (T) levels and regular menstrual cycles is as defined IH. Twenty (20) healthy women (mean age 23 +/- 2 years) (Group II) were included in this study as the control group. Insulin sensitivity was assessed with modified euglycemic insulin clamp technique. Samples of prolactin, luteinizing hormone (LH), follicle-stimulating hormone, adrenocorticotropic hormone (ACTH), dehydroepiandrosterone sulfate, cortisol, estradiol, progesterone, 17-OH progesterone (17-OHP), total T, and free T (FT) were obtained at baseline and at 2nd hour during clamp.

RESULTS

Steady-state (120 min) glucose disposal rates were higher in Group II than Group I (7.51 +/- 0.83 vs. 5.76 +/- 1.89 mg/kg/min). Mean FT, ACTH, cortisol, LH, prolactin and 17-OHP levels were found to have decreased statistically significantly (p < 0.05) in Group I. Mean FT, ACTH, and prolactin levels were found to have decreased statistically significantly (p < 0.05) in Group II during the clamp. Mean baseline levels of FT, LH and prolactin were greater in women with hirsutism than in the control subjects (p < 0.05). Insulin mediated glucose disposal was lower in the normal weight women with IH than in those without hirsutism.

CONCLUSIONS

Mean FT, 17-OHP and dehydroepiandrosterone sulfate levels decreased during euglcemic-hyperinsulinemic clamp in IH.

Steroidogenic alterations and adrenal androgen excess in PCOS

BACKGROUND

This cross-sectional study was undertaken to improve our understanding of the steroidogenic alterations leading to adrenal hyperandrogenism in polycystic ovarian syndrome (PCOS).

METHODS

Two-hundred and thirty-four women with clinical and biochemical features suggestive of PCOS underwent metabolic and hormonal evaluation. We used the androstenedione/DHEAS ratio as a surrogate for the level of ovarian 3betaHSD activity. We then selected the 90th percentile for the ratio in those with elevated DHEAS (>9 micromol/l) as the cut-off level beyond which excess DHEAS production will be minimized by excess ovarian 3betaHSD activity. This cut-off level was at a ratio of 1.5 and all PCOS women were then divided into two groups, the higher (>1.5) being the group with excess ovarian 3betaHSD activity. We hypothesized that women with a high ratio would be unlikely to have DHEAS excess due to the rapid conversion of DHEA to androstenedione. Those with a low ratio (concordant ovarian and adrenal steroidogenesis) could then either have high DHEAS or normal DHEAS, depending on whether CYP17 activity was higher or lower respectively.

RESULTS

Insulin resistance was found to be associated with decreased CYP17 activity while irregular cycles and neuroendocrine dysfunction were determined to be associated with higher ovarian 3betaHSD activity.

CONCLUSION

Adrenal androgen excess in PCOS seems to be related to insulin sensitivity as well as decreased activity of 3betaHSD, the latter being preferentially present in those women with regular cycles or without neuroendocrine dysfunction.

Exaggerated adrenarche and altered cortisol metabolism in Type 1 diabetic children

Reported literature data strongly suggest that steroid metabolism is dysregulated in Type 1 diabetes mellitus. The aim of this study was to non-invasively examine the cortisol metabolism in children with Type 1 diabetes mellitus (T1DM) in detail and to test the hypothesis that adrenarche is affected under conventional intensive insulin therapy. In 24-h urine samples of 109 patients aged 4-18 years with T1DM of more than 1 year, steroids were profiled using gas chromatography-mass spectrometry. Additionally, urinary free cortisol (UFF) and cortisone (UFE) were quantified by RIA after extraction and chromatographic purification. Data on urinary steroids from 400 healthy controls served as reference values. Enzyme activities were assessed by established steroid metabolite ratios, e.g. 5alpha-reductase and 11beta-hydroxysteroid dehydrogenase Type 2 (11beta-HSD2) by 5alpha-tetrahydrocortisol/tetrahydrocortisol and UFE/UFF, respectively. Urinary markers of adrenarche, especially dehydroepiandrosterone and its direct metabolites were elevated in patients, as were urinary 6beta-hydroxycortisol, UFE, and 11beta-HSD2 activity. However, overall cortisol secretion, as reflected by the sum of major urinary cortisol metabolites, was mostly normal and activity of 5alpha-reductase clearly reduced. Our study provides evidence for an exaggerated adrenarche in T1DM children, which may help to understand reported sequelae in female patients like hyperandrogenic symptoms. The findings also suggest a reduced cortisol inactivation via 5alpha-reductase that is not compensated by a fall in cortisol secretion. Whether the elevated urinary 6beta-hydroxycortisol and cortisone excretion, observed in the patients, are also present in other forms of hypercortisolism and may thus serve as non-invasive clinical stress markers deserves further study.

Hyperglycaemia acutely decreases circulating dehydroepiandrosterone levels in healthy men

OBJECTIVE

This study was conducted in order to evaluate the effect of glucose-insulin homeostasis on adrenal steroids and was designed to separate the effects of hyperglycaemia from those of insulin.

DESIGN

Eight healthy men aged 22.6 +/- 3.4 (SD) underwent an 80 mU/m2/min hyperinsulinaemic euglycaemic 100-min clamp, a 200-min graded glucose infusion at 2-16 mg/kg/min and a measurement of fat mass.

MEASUREMENTS

Circulating glucose, insulin and adrenal steroid levels including dehydroepiandrosterone (DHEA) were determined before and during both infusion tests. Steroid variations in relation to insulinaemia and glycaemia were analysed using univariate, multivariate tests and nonlinear mixed models.

RESULTS

Hyperinsulinaemia induced no significant modification of adrenal steroid levels. By contrast, hyperglycaemia decreased all adrenal steroids except DHEA-sulphate by 47-66%. The drop occurred early, averaging 51% for 17OH pregnenolone and 57% for DHEA at the 80th minute of glucose infusion, whereas blood glucose was 7.1 +/- 1.2 mmol/1. This effect was independent of insulinaemia, fat mass and waist circumference. Thus, we estimated models that could best predict steroid variations according to blood glucose. At thresholds defining impaired fasting glycaemia and diabetes, the estimated decrease in DHEA was 40% and 45%, respectively, culminating at 60% at 9.3 mmol/1 glycaemia, with no detectable further decrease.

CONCLUSIONS

Our data suggest that hyperglycaemia dramatically decreases adrenal androgen levels in men, possibly by acting at early steps of synthesis, independently of insulinaemia and fat mass.

Dehydroepiandrosterone mimics acute actions of insulin to stimulate production of both nitric oxide and endothelin 1 via distinct phosphatidylinositol 3-kinase- and mitogen-activated protein kinase-dependent pathways in vascular endothelium

Dehydroepiandrosterone (DHEA) is an adrenal steroid and nutritional supplement that may improve insulin sensitivity. Although steroid hormones classically act by regulating transcription, they may also signal through cell surface receptors to mediate nongenomic actions. Because DHEA may augment insulin sensitivity, we hypothesized that DHEA mimics vascular actions of insulin to acutely activate signaling pathways in endothelium-mediating production of nitric oxide (NO) and endothelin 1 (ET-1). Treatment of bovine aortic endothelial cells with either insulin or DHEA (100 nm, 5 min) stimulated significant increases in NO production (assessed with NO-selective fluorescent dye diaminofluorescein 2). These responses were abolished by pretreatment of cells with L-NAME (nitro-L-arginine methyl ester; NO synthase inhibitor) or wortmannin [phosphatidylinositol (PI) 3-kinase inhibitor]. Under similar conditions, insulin- or DHEA-stimulated phosphorylation of Akt (Ser473) and endothelial nitric oxide synthase (Ser1179) was inhibited by pretreatment of cells with wortmannin (but not MAPK kinase inhibitor PD98059). Acute DHEA treatment also caused phosphorylation of MAPK (Thr202/Tyr204) that was inhibitable by PD98059 (but not wortmannin). DHEA treatment of bovine aortic endothelial cells (100 nM, 5 min) stimulated a 2-fold increase in ET-1 secretion that was abolished by pretreatment of cells with PD98059 (but not wortmannin). We conclude that DHEA has acute, nongenomic actions in endothelium to stimulate production of the vasodilator NO via PI 3-kinase-dependent pathways and secretion of the vasoconstrictor ET-1 via MAPK-dependent pathways. Altering the balance between PI 3-kinase- and MAPK-dependent signaling in vascular endothelium may determine whether DHEA has beneficial or harmful effects relevant to the pathophysiology of diabetes.

The phosphatidylinositol/AKT/atypical PKC pathway is involved in the improved insulin sensitivity by DHEA in muscle and liver of rats in vivo

DHEA improves insulin sensitivity and has anti-obesity effect in animal models and men. However, the molecular mechanisms by which DHEA improves insulin action have not been clearly understood. In the present study, we examined the protein levels and phosphorylation state of insulin receptor (IR), IRS-1 and IRS-2, the association between IRSs and PI3K and SHP2, the insulin-induced IRSs associated PI 3-kinase activities, and the phosphorylation status of AKT and atypical PKCzeta/lambda in the liver and the muscle of 6 month-old Wistar rats treated with DHEA. There was no change in IR, IRS-1 and IRS-2 protein levels in both tissues of treated rats analysed by immunoblotting. On the other hand, insulin-induced IRS-1 tyrosine phosphorylation was increased in both tissues while IRS-2 tyrosyl phosphorylation was increased in liver of DHEA treated group. The PI3-kinase/AKT pathway was increased in the liver and the PI3K/atypical PKCzeta/lambda pathway was increased in the muscle of DHEA treated rats. These data indicate that these regulations of early steps of insulin action may play a role in the intracellular mechanism for the improved insulin sensitivity observed in this animal model.

PCOS: a diagnostic challenge

Useful research and diagnostic criteria for PCOS arose from a conference in 1990, whereby PCOS could be defined by: (i) clinical and/or biochemical hyperandrogenism, (ii) chronic anovulation, and (iii) exclusion of related disorders. The presence of "polycystic ovaries" was not included in this definition, which created significant concern since many women with PCOS have polycystic ovaries on ultrasound, and conversely women with this ovarian morphology have a higher prevalence of androgen excess and insulin resistance. More recently, at an expert meeting in 2003 in Rotterdam, it was recommended that PCOS be defined when at least two of the following three features were present, after exclusion of other aetiologies: (i) oligo- or anovulation, (ii) clinical and/or biochemical hyperandrogenism, or (iii) polycystic ovaries. These newer criteria effectively create additional phenotypes of PCOS (e.g. women with hyperandrogenism and polycystic ovaries but normal ovulatory function, and women with ovulatory dysfunction and polycystic ovaries but no clinical or biochemical evidence of hyperandrogenism). It remains to be demonstrated whether these phenotypes actually represent patients with PCOS. Nonetheless, the trend towards the use of uniform diagnostic criteria in studies of PCOS will increase the comparability and potentially the value of published research.

Circulating levels of neuroactive steroids in patients with binge eating disorder: a comparison with nonobese healthy controls and non-binge eating obese subjects

OBJECTIVES

Increased plasma levels of allopregnenolone (3alpha,5alpha-tetrahydroprogesterone [3alpha,5alpha-THP]), dehydroepiandrosterone (DHEA), and DHEA sulphate (DHEA-S) have been reported in patients with anorexia nervosa or bulimia nervosa. To assess whether those changes are related to malnutrition, we investigated plasma levels of neuroactive steroids in women with binge eating disorder (BED) who compulsively binge as bulimic patients, but do not incur malnutrition.

METHODS

Sixty-eight women participated in the study (31 nonobese healthy controls, 9 nonobese patients with BED, 16 obese patients with BED, and 12 obese non-binge eating women). Blood samples were collected in the morning for determination of plasma levels of 3alpha,5alpha-THP, DHEA, DHEA-S, and cortisol.

RESULTS

Nonobese BED women had significantly higher plasma levels of DHEA, DHEA-S, and 3alpha,5alpha-THP than nonobese healthy women. Similarly, obese individuals with BED exhibited significantly higher neurosteroid plasma levels than non-binge eating obese subjects. No significant differences in plasma cortisol levels were observed among the groups.

DISCUSSION

This study shows increased plasma levels of neuroactive steroids in BED patients. These findings could have been influenced by methodologic limitations (e.g., the absence of diurnal sampling). However, they suggest that if malnutrition is involved in the determination of increased plasma levels of neuroactive steroids in people with anorexia or bulimia nervosa, then different factors may induce similar effects in people with BED. Alternatively, common unknown factors could be responsible for neurosteroid changes in anorexia nervosa, bulimia nervosa, and BED.

Dehydroepiandrosterone: is there a role for replacement?

Dehydroepiandrosterone (DHEA) and its sulfated ester are found in high concentrations in the plasma; however, their role in normal human physiology, other than as precursors for sex hormones, remains incompletely defined. Studies of rodent models have shown that these hormones have beneficial effects on a wide variety of conditions, such as diabetes, obesity, immune function, atherosclerosis, and many of the disorders associated with normal aging. However, rodents are not the best models to study the actions of these hormones because they have very little endogenous DHEA; thus, the doses given to these animals are usually suprapharmacological. Human studies have been performed to determine the potential beneficial effects of DHEA replacement in persons with low DHEA levels. Results have been conflicting. Human studies suggest a potential role for DHEA replacement in persons who have undergone adrenalectomy and possibly in the aging population. However, long-term studies assessing the benefits vs adverse effects must be done before DHEA replacement can be recommended.

Troglitazone decreases adrenal androgen levels in women with polycystic ovary syndrome

OBJECTIVE

To determine whether amelioration of insulin resistance in polycystic ovary syndrome (PCOS) with the insulin sensitizer troglitazone (TGZ) decreases circulating adrenal androgens (AAs), as reflected by DHEAS levels.

DESIGN

Prospective, randomized, double-blind clinical trial.

SETTING

Multicenter study.

SUBJECT(S)

Three-hundred five women with PCOS.

INTERVENTION(S)

Subjects were randomly assigned to receive either placebo (PBO; n = 73) or TGZ in doses of 150 mg/day (TGZ-150; n = 78), 300 mg/day (TGZ-300; n = 77), or 600 mg/day (TGZ-600; n = 77) for 20 weeks. Blood was sampled before (week 0) and at week 20 of treatment.

MAIN OUTCOME MEASURE(S)

DHEAS, insulin, and glucose levels were determined in the blood samples.

RESULT(S)

There were no differences in age, body mass, or racial composition among the groups. Our results indicate that basal insulin declined in a dose-related fashion. Likewise, TGZ administration caused a dose-related decrease in DHEAS levels. To detect extreme effects, we subsequently subdivided patients receiving PBO or TGZ-600 into tertiles according to initial DHEAS levels. Patients receiving PBO in the lowest (n = 27) and highest (n = 22) DHEAS tertiles experienced a 16.8% +/- 62.0% and a -11.1% +/- 17.4% change in DHEAS levels during the study, respectively. Alternatively, patients with PCOS receiving TGZ-600 in both the lowest (n = 29) and the highest (n = 23) DHEAS tertiles experienced a drop in DHEAS levels (-18.7% +/- 27.2% and -26.4% +/- 17.2%, respectively), a significant difference from PBO.

CONCLUSION(S)

In conclusion, improving the insulin resistance-related hyperinsulinemia of PCOS with TGZ results in a decrease in DHEAS levels, regardless of initial DHEAS level. Whether the observed suppression is the direct result of decreased insulin levels or whether it reflects other direct and indirect effects of TGZ remains to be determined.

Dehydroepiandrosterone sulphate is increased and dehydroepiandrosterone-response to corticotrophin-releasing hormone is decreased in the hyperthyroid state compared with the euthyroid state

OBJECTIVE

Dehydroepiandrosterone (DHEA) and DHEA-sulphate (S) have been suggested to play protective roles in many pathological states, some of which are observed in hyperthyroidism. If DHEA and DHEA-S levels change in hyperthyroidism, they might participate as a possible causative link with such pathophysiological changes in hyperthyroidism. However, the CRH-ACTH-DHEA system in hyperthyroidism has not been clearly defined. We examined plasma levels of DHEA and DHEA-S together with ACTH and cortisol in both hyperthyroid (Hyper) and euthyroid states (Eu).

METHODS

Eighteen patients (5 men and 13 women, aged 46.9 +/- 2.8 years) with Graves' disease were studied before treatment and again in the euthyroid state following treatment with methimazole. A 100 microg hCRH stimulation test and a low-dose (0.5 microg) 1-24 ACTH stimulation test were performed on separate days. Basal levels and A area under the response curve (AUC) were compared between Hyper and Eu.

RESULTS

DHEA-S was higher in Hyper than in Eu. However, basal DHEA did not differ between Hyper and Eu. The ratio of DHEA to DHEA-S was lower in Hyper than in Eu. AAUC of DHEA during a CRH test was lower in Hyper than in Eu. However, AAUC of DHEA during an ACTH test was similar in both Hyper and Eu. Basal ACTH was higher in Hyper than in Eu. In both CRH and ACTH tests, AAUC of cortisol response was lower in Hyper than in Eu, although the basal cortisol level was not different.

CONCLUSION

The balance of the conversion between DHEA-S and DHEA in the hyperthyroid state favoured DHEA-S. Similar to cortisol, the DHEA response in the CRH test in hyperthyroidism seemed to be insufficiently compensated for by increased ACTH, although the DHEA response to low-dose ACTH was similar in the hyperthyroid and euthyroid states. Increased DHEA-S might play some role in the pathological states in many organs in hyperthyroidism.

The role of the adrenal cortex in polycystic ovary syndrome

Adrenal androgen excess affects approximately 25% of PCOS patients. The exact etiology of this excess in PCOS patients is unclear. Some evidence that adrenal androgen excess may be a genetic trait. The adrenal androgen response to ACTH is highly individualized, and the relative response seems to be constant over time. In addition, there is a strong familial component to adrenal androgen levels in normal individuals and PCOS patients. It is possible that the tendency to overproduce adrenal androgens is an inherited risk factor for the development of PCOS. Overall, few hyperandrogenic patients actually have isolated deficiencies of 3 beta-hydroxysteroid dehydrogenase, 21-hydroxylase, and 11-hydroxylase. The ovarian hormonal secretion in PCOS can affect adrenal androgen secretion and metabolism, although this factor accounts for only part of this abnormality. More likely, the adrenal androgen excess results from a generalized hyperresponsiveness of the adrenal cortex to ACTH, but without an increase in CRH or ACTH sensitivity. Although glucocorticoid administration may improve the ovulatory function of these patients, the results are modest and cannot be predicted by the circulating androgen levels.

Adrenal responsiveness to high, low and very low ACTH 1-24 doses in obesity

OBJECTIVE

To investigate adrenal activity in visceral obesity in which adrenal hyperactivity has been hypothesized. This could reflect hypothalamus-pituitary alterations leading to slight hyperfunction of the adrenal. Primary adrenal hypersensitivity to ACTH drive in obesity has also been suggested. However, it has also been reported that dehydroepiondrosterone (DHEA) levels in obesity are reduced and it has been hypothesized that this could play a role in the increased cardiovascular risk in obese patients.

SUBJECTS

We have studied seven obese women with visceral adiposity (OB, age: 33.6+/-3.3 years, BMI: 33.8+/-1.3 kg/m2, WHR: 0.88+/-0.01). The results in OB were compared with those recorded in a group of age-matched normal women (NS, age: 30+/-1.3 years, BMI: 19.9+/-0.4 kg/m2, WHR: 0.76+/-0.02).

METHODS

We have studied the cortisol (F), aldosterone (A) and DHEA responses to ACTH 1-24 administered at low (LD, 0.5 microg/m2) or very low (VLD, 0.125 microg/m2) dose followed by a second challenge with supramaximal dose (HD, 250 microg).

RESULTS

Basal F, A and DHEA levels in OB were similar to those in NS. The peak F responses to ACTH were dose-related in both groups. At each dose the F peaks in OB (VLD: 495.6+/-43.9 nmol/l, HD: 722.3+/-67.7 nmol/l; LD: 519.2+/-46.0 nmol/l, HD: 729.6+/-44.7 nmol/l) were similar to those in NS (VLD: 556.7+/-45.9 nmol/l, HD: 704.8+/-20.7 nmol/l; LD: 511.8+/-22.8 nmol/l, HD: 726.7+/-26.5 nmol/l). The peak A responses to ACTH were dose-related in both groups. At each dose, the A peaks in OB (VLD: 0.55+/-0.03 pmol/l, HD: 0.79+/-0.09 pmol/l; LD: 0.63+/-0.04 pmol/l, HD: 0.78+/-0.09 pmol/l) were similar to those in NS (VLD: 0.8+/-0.10 pmol/l, HD: 0.86+/-0.09 pmol/l; LD: 0.8+/-0.10 pmol/l, HD: 0.95+/-0.12 pmol/l). The peak DHEA responses to ACTH were dose-related in both groups. At each dose the DHEA peaks in OB (VLD: 58.6+/-13.3 nmol/l, HD: 61.9+/-13.1 nmol/l; LD: 55.18+/-6.4 nmol/l, HD: 72.3+/-9.8 nmol/l) were similar to those in NS (VLD: 54.3+/-8.2 nmol/l, HD: 57.8+/-8.2 nmol/l; LD: 42.2+/-3.7 nmol/l, HD: 56.9+/-4.3 nmol/l).

CONCLUSIONS

This study shows that the cortisol, aldosterone and dehydroepiondrosterone responses to high, low and very low ACTH doses in obese women overlap with those in age-matched lean controls; these findings suggest normal sensitivity of the different zones of the adrenal cortex to ACTH in obesity.

Metformin therapy decreases hyperandrogenism and hyperinsulinemia in women with polycystic ovary syndrome

OBJECTIVE

To evaluate the effects of 12 weeks of metformin therapy on hormonal and clinical indices in polycystic ovary syndrome (PCOS).

DESIGN

Prospective study.

SETTING

University hospital.

PATIENT(S)

Thirty-nine women with PCOS and fasting hyperinsulinemia.

INTERVENTION(S)

Twelve weeks of therapy with oral metformin (500 mg three times per day).

MAIN OUTCOME MEASURE(S)

Levels of insulin, T, DHEAS, insulin-like growth factor-I (IGF-I), gonadotropins, and sex hormone-binding globulin (SHBG); and clinical symptoms including acne, hirsutism, and length of the menstrual cycle were assessed before and after treatment with metformin.

RESULT(S)

Metformin therapy resulted in a significant decrease in fasting insulin and total T and an increase in SHBG, leading to a decrease in the free T index. In addition, there was a significant decline in mean body mass index, waist-hip ratio, hirsutism, and acne, as well as an improvement in the menstrual cycle. No changes in LH and LH-FSH ratio were observed. Multiple regression analysis demonstrated that the greatest decline of T and free T index in response to metformin was observed among patients with the most pronounced hyperandrogenemia. Subjects with elevated DHEAS differed from those with normal DHEAS in their responses to metformin treatment. Women with high DHEAS exhibited less improvement of menstrual cycle regularity, no change in hirsutism, and an increase in levels of IGF-I after treatment.

CONCLUSION(S)

Metformin treatment of women with PCOS results in a decline of insulin as well as total and bioavailable T, leading to significant improvement of clinical manifestations of hyperandrogenism. Responses to metformin are related to the severity of hyperandrogenemia and to adrenal function.

Evidence that insulin and androgens may participate in the regulation of serum leptin levels in women

OBJECTIVE

Although serum leptin is principally influenced by body mass, to understand the role of insulin and androgens in the regulation of serum leptin in normal weight women.

DESIGN

Prospective observational study.

SETTING

Academic practice in reproductive endocrinology.

PATIENT(S)

Twenty-one women with polycystic ovary syndrome (PCOS) of normal body weight, 8 apparently normal women with polycystic-appearing ovaries (PAO), and 21 normal women.

INTERVENTION(S)

Fasting blood levels of luteinizing hormone, follicle-stimulating hormone, testosterone (T), unbound T, dehydroepiandrosterone sulfate (DHEAS), insulin, insulin growth factor-binding protein-1 (IGFBP-1), and leptin.

MAIN OUTCOME MEASURE(S)

Comparisons of measured hormones in the different groups and correlative analysis

RESULT(S)

Women with PCOS had higher levels of serum luteinizing hormone, T, unbound T, DHEAS and insulin, and lower levels of IGFBP-1 compared with the normal controls, but they had similar leptin levels. Normal women with PAO had increased levels of insulin and leptin compared with controls, whereas IGFBP-1 was lower in PAO. In normal weight women with PCOS and PAO, leptin correlated positively with body weight and insulin, and negatively with IGFBP-1 and DHEAS.

CONCLUSION(S)

In normal weight patients serum leptin levels may be regulated in part by insulin. Androgens, on the other hand, may play a role in suppressing serum leptin.

The role of dehydroepiandrosterone in diabetes mellitus

Much has been written in the lay literature regarding potential benefits of dehydroepiandrosterone (DHEA). Although it was removed from the over-the-counter market in 1985, the Dietary Supplement Health Education Act of 1994 allowed the drug to be marketed as a food supplement. Because DHEA no longer falls under the scrutiny of the Food and Drug Administration, many unverified claims have been put forth in the press espousing its therapeutic value. This barrage of "infomercials" has left the average American consumer (and health care professional) curious about DHEA and its possible therapeutic utility. One focus of recent research is to define the role of DHEA in diabetes mellitus. Although it has been claimed that decreased levels of endogenous DHEA are associated with diabetes, impaired glucose tolerance, hyperglycemia, and insulin resistance, much of the information is based on cross-sectional studies. Other claims correlate decreased endogenous DHEA levels with adverse cardiovascular effects. Some information is contradictory and indicates high doses of exogenous DHEA may produce adverse cardiovascular effects, an undesirable outcome in patients with diabetes mellitus. At this time, its administration in patients with diabetes is not warranted. Long-term trials evaluating the role of exogenous DHEA and its effect on patients with diabetes should be conducted.

Relationships between dehydroepiandrosterone-sulphate and anthropometric, metabolic and hormonal variables in a large cohort of obese women

OBJECTIVE

The aim of the present study was to measure dehydroepiandrosterone-sulphate (DHEA-S) levels in obesity and assess the relationships between DHEA-S and anthropometric, metabolic and hormonal variables.

SUBJECTS AND METHODS

We evaluated the serum DHEA-S levels in 217 obese but otherwise normal female subjects (age (mean +/- SEM): 39.4 +/- 0.9, range 18-67 years, body mass index (BMI) = 36.1 +/- 0.4, range 27.1-57.1 kg/m2).

RESULTS

DHEA-S levels showed an age-dependent fall similar to that observed in normal women (n = 156, age 46.2 +/- 1.2, range 22-69 years, BMI < 25 kg/m2). Adjusting for age, obese women had mean DHEA-S levels higher than the control group (P < 0.02). In obese patients, DHEA-S levels were directly associated with serum testosterone, androstendione, IGF-I, fT3 levels and 24 h-urinary cortisol. On the other hand, DHEA-S levels were negatively associated with age, total cholesterol, triglycerides levels and systolic blood pressure. No correlation was found with BMI, waist:hip ratio, basal and post-OGTT insulin and glucose, free fatty acids, GH, PRL, fT4, TSH, SHBG levels or diastolic blood pressure. Multiple regression analysis indicated that in obese women, DHEA-S levels were associated negatively to age and positively to testosterone, androstendione and IGF-I levels and daily urinary cortisol. In a subgroup of 20 obese women, DHEA-S levels significantly (P < 0.001) fell after OGTT without any correlation with the insulin response.

CONCLUSIONS

The present results show that dehydroepiandrosterone-sulphate levels are not reduced in obesity, being slightly increased, particularly in young adulthood. Dehydroepiandrosterone-sulphate levels are positively and independently associated with androgen, 24-h urinary cortisol and IGF-I levels but do not seem associated with insulin levels or cardiovascular risk indices.

Changes in sex hormones during an oral glucose tolerance test in healthy premenopausal women

OBJECTIVE

To assess the effect of an acute elevation in circulating insulin on serum androgen levels in healthy obese women with different body-fat distributions.

DESIGN

Controlled clinical study.

SETTING

The Endocrinology Unit of an academic medical center.

PATIENT(S)

Seventy healthy premenopausal women participated: 27 women with upper-body obesity, 22 women with lower-body obesity, and 21 normal-weight women as controls.

INTERVENTION(S)

A 75-g oral glucose tolerance test (OGTT) was performed for all participants.

MAIN OUTCOME MEASURE(S)

Anthropometry and serum concentrations of glucose, insulin, free T, DHEAS, androstenedione, E2, and sex hormone-binding globulin (SHBG) at fasting, 60 minutes, and 120 minutes after oral glucose loading.

RESULT(S)

Although androgens and E2 levels in all three groups declined modestly, there were no statistically significant differences in response of the sex hormones to an OGTT in the two obese groups and normal-weight women. No correlation was found between changes in sex-hormone levels during an OGTT and insulin rise. Increased body mass index and more pronounced abdominal fat localization resulted in basal hyperinsulinemia, markedly exaggerated glucose-induced insulin levels, and hyperandrogenism, as was evident by significantly elevated free T and low SHBG serum levels.

CONCLUSION(S)

There were no statistically significant differences in androgen response to acute hyperinsulinemia during an OGTT between obese women with different regional fat distributions and lean controls.

Reduced serum dehydroepiandrosterone levels in diabetic patients with hyperinsulinaemia

OBJECTIVE

To elucidate the interaction between insulin and dehydroepi-androsterone (DHEA) concentrations, we evaluated serum DHEA and DHEA-sulphate (DHEA-S) levels in diabetic patients with hyperinsulinaemia.

PATIENTS AND DESIGN

Twenty-four subjects with non-insulin dependent diabetes mellitus, 12 hyperinsulinaemic subjects (fasting serum insulin concentrations > or = 10 mU/ml (71.8 pmol/l)) and 12 non-hyperinsulinaemic subjects, and 10 normal control subjects were studied. Serum DHEA, DHEA-S, cortisol and ACTH levels were investigated in these subjects. Moreover, their serum DHEA levels were compared during hyperinsulinaemic-euglycaemic clamp and after ACTH stimulation.

MEASUREMENTS

Serum insulin, cortisol, ACTH, DHEA and DHEA-S concentrations were evaluated by RIA. Serum glucose was determined by the glucose oxidase method.

RESULTS

Diabetic patients with hyperinsulinaemia showed significantly lower levels of serum DHEA and DHEA-S than controls. After ACTH stimulation, these patients also showed significantly lower DHEA levels. During the hyperinsulinaemic-euglycaemic clamp, serum DHEA concentrations of diabetic patients with hyperinsulinaemia remained low and did not decline further, although those of control subjects and non-hyperinsulinaemic diabetic patients showed a significant decline of serum DHEA levels. Even after ACTH stimulation during the clamp, serum DHEA in hyperinsulinaemic patients was still significantly lower than in controls.

CONCLUSIONS

In diabetic patients with hyperinsulinaemia, baseline DHEA levels are chronically and maximally suppressed compared to control subjects and non-hyperinsulinaemic diabetic patients, and thus not decreased further by exogenous insulin infusion during hyperinsulinaemic-euglycaemic clamp.

The acute effect of dexamethasone on plasma leptin concentrations and the relationships between fasting leptin, the IGF-I/IGFBP system, dehydroepiandrosterone, androstenedione and testosterone in an elderly population

OBJECTIVE

To investigate the acute effect of dexamethasone administration on serum leptin levels and the relationships between dehydroepiandrosterone (DHEAS), androstenedione, testosterone and the IGF-I/IGFBP system and leptin levels in healthy elderly humans.

METHODS

In 209 healthy elderly individuals (95 men, 114 women, aged 55-80 years) measurements were made in the fasting state (0800 h) and after an overnight dexamethasone suppression test (1 mg p.o. at 2300 h.

RESULTS

Mean leptin levels increased from 6.2 +/- 0.4 (SE) micrograms/l to 7.3 +/- 0.5 (SE) micrograms/l in men and from 18.9 +/- 1.4 (SE) micrograms/l to 23.9 +/- 1.8 (SE) micrograms/l in women after 1 mg dexamethasone overnight ('post treatment')(P < 0.001 for both sexes). There was a significant relationship between post-treatment leptin and dexamethasone levels (men: P = 0.002; women: P < 0.001). The increase in leptin levels after dexamethasone administration was only partially related to the increase in plasma insulin concentrations. Cortisol levels were not related to leptin. In multivariate analyses the relationship between post-treatment leptin and dexamethasone levels remained after adjustment for post-treatment insulin levels, BMI, waist:hip ratio (WHR) and age (men: P < 0.001; women: P = 0.001). Plasma (free and total) IGF-I and IGFBP-3 levels were not related to leptin levels in men or women. IGFBP-1 levels were inversely related to leptin levels (P = 0.02), but this relationship was lost after adjustment for insulin, and/or BMI. In multivariate analyses the relationship between leptin and DHEAS was inverse in women (P = 0.04) (after adjustment for BMI, WHR, insulin and glucose), while there was no relationship between leptin and DHEAS in men.

CONCLUSIONS

Administration of dexamethasone acutely increased leptin levels within 9 h in this elderly population. This increase was only partly related to changes in circulating insulin concentrations, but was independent of BMI and waist:hip ratio. No relation existed between leptin and (free or total) IGF-I and IGFBP-3 in men or women. Dehydroepiandrosterone was inversely related to leptin in women. These findings suggest a contributory regulatory role for corticosteroids in modulating circulating leptin concentrations in elderly healthy individuals of both sexes, which is at least in part independent of insulin, BMI and waist:hip ratio. Dehydroepiandrosterone might play a role in the gender-specific differences in serum leptin levels.

Oral glucose challenge effects on growth and sex steroid hormones in normal women and women with hypothalamic amenorrhea

OBJECTIVE

To investigate the effect of growth hormone (GH) on the serum levels of ovarian and adrenal sex steroid hormones in women with hypothalamic amenorrhea (HA).

METHODS

A standard 75-g oral glucose tolerance test (OGTT) was performed in 12 normal women and 16 women with stress-related or weight-loss-related amenorrhea.

RESULTS

Significant progressive declines in GH, testosterone (T), estradiol (E2) and dehydroepiandrosterone sulfate (DHEAS) were observed during the OGTT in the normal and HA groups. Significant positive correlations were observed between GH and T, E2 and DHEAS. The area under the curve (AUC) for the GH response was significantly greater in the HA group than in the normal group. The ratio of the AUC of insulin-like growth factor to that of GH was significantly lower in the HA group.

CONCLUSIONS

Growth hormone may modify ovarian and adrenal sex steroidogenic responses to tropic hormones. A significant degree of GH resistance exists in HA patients. This GH resistance may be related to an ovulatory disturbance.

Low dehydroepiandrosterone sulfate and heart disease in middle-aged men: cross-sectional results from the Massachusetts Male Aging Study

PURPOSE

Serum concentrations of the adrenal androgen dehydroepiandrosterone (DHEA) and its sulfate ester (DHEAS), both of which decline with age more markedly than other sex hormone levels, have been alternately credited and discredited as "protective" correlates of heart disease. Baseline data from the Massachusetts Male Aging Study (MMAS), collected in 1987-89, provided a large population-based random sample (n = 1709) in which to examine cross-sectionally the relation of DHEA and DHEAS levels to heart disease, while controlling for a comprehensive set of potential confounders including serum lipid and hormone levels as well as smoking, alcohol intake, obesity, hypertension, diabetes, diet, medication, physical activity, and psychological measures.

METHODS

The subjects were men aged 40-70 years, randomly sampled from the Massachusetts state census listing, measured and interviewed at home. Nonfasting blood samples were assayed for hormones and lipids.

RESULTS

In all strata of age, smoking, and alcohol intake, the age-adjusted odds ratio for self-reported heart disease was between 0.55 and 0.85 per standard deviation (SD) of log DHEA and DHEAS concentration. Multiple logistic regression analysis indicated a strong independent role for DHEAS as a predictor of self-reported heart disease, controlling for age and the potential confounders listed above. The multiply-adjusted odds ratio for heart disease was 0.64 per SD log DHEAS concentration, with 95% confidence interval (CI) 0.50-0.83 (P = 0.0002). The DHEAS effect was not diminished by controlling for use of cardiac, vasodilator, antihypertensive, or lipid-lowering medication.

CONCLUSIONS

These findings suggest that serum DHEAS levels bear an inverse relationship to heart disease, independently of a large set of established cardiovascular risk factors. The cross-sectional nature of this study requires that the findings be interpreted with caution.

Effect of growth hormone suppression on the serum levels of ovarian and adrenal sex steroid hormones in normal women and in women with polycystic ovary syndrome

We investigated the acute effect on the serum levels of ovarian and adrenal sex steroid hormones of the suppression of growth hormone during oral glucose tolerance test (OGTT). A standard 75 g OGTT was performed in 11 healthy women and eight women with polycystic ovary syndrome (PCOS). Another five controls were given a sham loading of oral distilled water. Blood samples were obtained immediately before and at 30-minute intervals after glucose or sham loading. Significant progressive declines in testosterone, estradiol, dehydroepiandrosterone sulfate (DHEAS) and growth hormone levels were observed during OGTT in both groups. In the PCOS and normal groups, respectively, at 120 min, testosterone levels were 75.8% and 64.4% of the baseline (0-time) value, estradiol levels were 83.4% and 83.1%, DHEAS levels were 79.3% and 79.1%, and growth hormone levels were 33.9% and 21.2%. Significant positive correlations were observed between the level of growth hormone and each of the testosterone, estradiol and DHEAS levels in both the groups. The area under the curve for growth hormone was significantly smaller in the PCOS group than in the normal group. Gonadotropins were not changed at any time during OGTT. It appears that growth hormone may modify ovarian and adrenal sex steroidogenic responses to tropic hormones directly or via local insulin-like growth factor-I. Women with PCOS may be relatively deficient in growth hormone, a deficiency which may play a role in the pathophysiology of ovulatory disturbance.

Ageing and adrenal cortical function

Ageing is associated with changes in the secretion of adrenal cortical steroids. In the elderly, cortisol secretion increases after stimulation, while the secretion of dehydroepiandrosterone (DHEA) decreases. Each of these hormones influences the age-related processes of energy metabolism, fat depot distribution, immune function and neurodegeneration. In animals the effects of adrenal steroids are dramatic and easily measured. In humans the effects are more subtle. This review summarizes these actions and emphasizes the differences of dosages used in various experimental designs. It is concluded that adrenal hormones may play a significant role in human ageing, but research is hindered because the molecular pathways of DHEA action are not known.

Effects of aging on dehydroepiandrosterone sulfate in relation to fasting insulin levels and body composition assessed by bioimpedance analysis

Insulin can inhibit dehydroepiandrosterone (DHEA) biosynthesis in humans, as suggested by several studies performed in induced or spontaneous hyperinsulinemia. The increased insulin resistance documented throughout aging, with its accompanying hyperinsulinemia, may contribute to the age-related decline in DHEA synthesis. The aim of this study was to assess if the aging-related differences in DHEA sulfate (DHEA-S) serum levels can be associated with differences in fasting insulin levels, as well as body composition. Two hundred fifty-two healthy subjects of both sexes aged 19 to 90 years with a body mass index (BMI) less than 30 (mean +/- SD, 23.5 +/- 2.4) were studied DHEA-S and insulin serum levels were determined by a radioimmunologic procedure; body composition was assessed by anthropometry (fat mass percentage [FM%] estimated from four skinfold thicknesses by Durnin and Womersley and Siri equations [FM%-SKF]) and by bioimpedance analysis (BIA) (FM% estimated by equations developed by Segal et al and Deurenberg et al for subjects < and > 62 years, respectively [FM%-BIA]). DHEA-S levels were significantly and inversely related to age in both sexes. No significant aging-related differences were found in fasting insulin levels, although a trend toward an increase was apparent in the women on simple regression analysis. No significant associations were found between DHEA-S and insulin levels. As for body composition, a positive relationship to age was apparent for FM%-SKF, FM%-BIA, and waist to hip ratio (WHR), whereas BMI and phase angle ([PA] a bioelectric parameter considered an index of the ratio between intracellular and extracellular water) were inversely related to age. Fasting insulin levels were positively related to FM% as estimated by both BIA and anthropometry, independently of age in both sexes; in addition, a positive correlation with WHR and with the subscapular to triceps skinfold thickness ratio (SS/TS) was found in men and women, respectively. No significant correlation was apparent between DHEA-S and body composition indices in men, whereas in women a slight negative correlation between DHEA-S and WHR was documented, and was still significant after adjustment for age and fasting insulin. Stepwise multiple regression analysis confirmed that DHEA-S levels are not related to fasting insulin, but are independently related to age and, in women only, to WHR. Our study suggests that the DHEA-S decline due to aging is independent of fasting insulin, at least in healthy, non-obese people. In addition, it is not related to the aging-dependent changes in body composition in terms of FM% and fat-free mass (FFM) percentage (FFM%). Only in women could changes in fat distribution be slightly associated with DHEA-S decline, although such a relation cannot be accounted for by changes in insulin levels.

Dehydroepiandrosterone (DHEA) and aging

Dehydroepiandrosterone sulfate (DHEAS) is the most abundant circulating steroid hormone in humans and can readily be converted to its parent steroid DHEA by tissue sulfatases. Yet, a biologic function for these steroids has not been defined. The link between DHEA and aging has been raised by: (1) its well documented age-related decline, and (2) a preventive effect of DHEA on numerous age-related illnesses: ischemic heart-disease, cognitive impairment, immunodeficiency, malignancies, osteoporosis. These effects have been suggested by epidemiological studies in humans. Animal studies support a protective effect of DHEA on these age-related diseases. However, it remains unknown whether these results in animals can be transposed in humans, because adrenal secretion of DHEA seems to be particular to primates. In humans, only a few studies have been performed. The effects of oral supplementation with DHEA have, so far, focused on the possible metabolic effects of DHEA. A few studies have shown: the absence of any side-effects; no change in body-weight; conflicting results on body-composition and lipids and no effect on insulin-tolerance. The latest study showed a beneficial effect on well-being but these results need to be confirmed.

Induction of steroidogenic enzyme genes by insulin and IGF-I in cultured adult human adrenocortical cells

Insulin and the insulin-like growth factors (IGFs) have multiple role in gene expression in steroidogenic cells. We investigated the regulation of steroidogenic enzyme gene expression by insulin and IGF-I in primary cultures of human adrenocortical cells from donors of ages 19-77 years. The effects of insulin and IGF-I observed here were independent of age and sex of the donor. After 5 days in serum-containing medium, cultures were exposed to insulin or IGF-I together with cyclic AMP analogs or ACTH in serum-free defined medium. Insulin and IGF-I at physiological concentrations increased mRNA levels for 17 alpha-hydroxylase and type II 3 beta-hydroxysteroid dehydrogenase (3 beta-HSD) in the absence of cyclic AMP or ACTH. They had lesser effects on 21-hydroxylase and cholesterol side-chain cleavage enzyme mRNA levels and were3 without effect on 11 beta-hydroxylase mRNA. All steroidogenic enzyme mRNAs were strongly increased by cyclic AMP or ACTH, and this increase was potentiated by insulin or IGF-I. These effects of insulin and IGF-I were accompanied by decreases in the ratio of dehydroepiandrosterone/cortisol synthesized from pregnenolone by the cultures. Induction of steroidogenic enzyme genes in adult human adrenocortical cells by insulin and IGF-I is unlikely to occur by means of a cyclic AMP-dependent mechanism. These data increase the evidence for an important regulation of steroidogenesis by these hormones.

A moderate increase in daily protein intake causing an enhanced endogenous insulin secretion does not alter circulating levels or urinary excretion of dehydroepiandrosterone sulfate

To study the effect of a moderate increase in insulin secretion produced by an increased daily protein intake on dehydroepiandrosterone sulfate (DHEAS), a balanced randomized crossover trial consisting of three strictly controlled dietary regimens was performed in six healthy male volunteers. The basic diet (B) contained 50 g protein/d; diets P and M (also basic diets) were enriched with either 32 g protein/d (P) or 10 mmol L-methionine/d (M). Methionine was given (as a specific nonprotein source of endogenously derived sulfate) to control for possible confounding effects on DHEAS due to an increased sulfate supply. At the end of each 4-day diet period, blood and 24-hour urine samples were collected. Fasting plasma levels of testosterone, cortisol, insulin-like growth factor-I (IGF-I), and insulin, as well as urinary output of total (hot acid-cleaved) testosterone conjugates and 3alpha-androstanediol glucuronide, did not show significant changes in response to dietary manipulations. Endogenous sulfate availability (as reflected by renal sulfate output per 24 hours) approximately doubled with diets P and M. However, plasma levels (6.3 +/- 1.5, 6.8 +/- 1.8, and 6.9 +/- 2.1 micromol/L for B, P, and M, respectively) and urinary excretion (8.8 +/- 9.8, 9.4 +/- 11.2, 8.0 +/- 8.3 micromol/d) of DHEAS remained unaffected. Considering the clear increments (P < .01) in urinary C-peptide excretion with diet P (20.4 +/- 10.3 nmol/d) versus diets B and M (12.6 +/- 5.1 and 13.2 +/- 3.6 nmol/d), respectively, our results suggest that a moderately strong diet-induced increase in daily insulin secretion does not alter urinary and plasma levels of DHEAS.

The short-term effect of dietary pectin on plasma levels and renal excretion of dehydroepiandrosterone sulfate

Studies specifically investigating the effects of single dietary components on plasma levels of dehydroepiandrosterone (DHEA) and its sulfate ester (DHEAS) are rare. Especially no data is available with regard to specific dietary fibers. Therefore, the impact of pectin (a representative fiber that affects the enterohepatic recirculation of bile acids) was studied in a randomized crossover trial consisting of three diet periods characterized by the same food supply and daily doses of 0 g, 15 g or 30 g pectin. Blood and 24-h-urine samples were collected at the end of each 4-day diet period from 6 healthy male volunteers. Plasma levels of DHEA, cortisol and the major binding protein of DHEAS albumin remained unchanged with the varying pectin supplements. Also, no changes were observed for several urinary analytes including urinary DHEAS. However, effects of pectin intake (30, 15 versus 0 g/d) were seen for plasma DHEAS (9.3 +/- 2.8, 9.2 +/- 2.6, 8.0 +/- 3.1 mumol/L, p < 0.01) and total plasma cholesterol (4.4 +/- 0.7, 4.5 +/- 0.7, 4.7 +/- 0.8 mmol/L, p = 0.1). Obviously, the altered intake of fiber in the form of pectin affects plasma concentrations of DHEAS and cholesterol in an opposite direction. The reason for this is not known but a dietetically induced modulation of the binding properties of plasma albumin for DHEAS appears possible. Our findings suggest that the target tissue-available, not protein-bound fraction of circulating DHEAS (as reflected by the renal DHEAS output) is not necessarily altered when total plasma concentrations of DHEAS vary.

Decreased androgen levels and obesity in men

Obesity in males is accompanied by a significant decrease in testosterone levels. This decrease is essentially a consequence of the decrease of the sex hormone binding hormone (SHBG) binding capacity, itself probably the consequence of the increased insulin levels. In moderate obesity, free testosterone levels are normal, however, and there does not exist a real hypogonadism. In massively obese males, on the other hand, there is real hypogonadotrophic hypogonadism, with decreased free testosterone levels. The latter are the consequence of functional alterations at the hypothalamopituitary pole of the testicular axis, characterized by a decreased amplitude of the LH pulses. The decrease in adrenal androgen (DHEAS) levels is moderate and although it has been claimed that the increased insulin levels may play a causal role, the exact mechanism of this decrease is still a matter of controversy.

Androgens and insulin resistance in type 1 diabetic men

OBJECTIVE

In healthy men, both high and low serum testosterone concentrations are associated with insulin resistance, whereas low concentration of sex hormone binding globulin (SHBG) is related to reduced insulin sensitivity. The aim of our study was to examine the association of sex hormones, SHBG, dehydroepiandrosterone (DHEAS) and insulin-like growth factor binding protein-1 (IGFBP-1) on insulin sensitivity in type 1 diabetic patients.

PATIENTS

We examined 23 male patients with the mean age of 29 +/- 1 years, body mass index 22.9 +/- 0.4 kg/m2, insulin dose 47 +/- 3 units/day, glycosylated haemoglobin (HbA1c) 7.8 +/- 0.3% and duration of diabetes 13 +/- 1 years.

DESIGN

Each patient was studied with a 4-hour euglycaemic (5.5 +/- 0.1 mmol/l), hyperinsulinaemic (612 +/- 26 pmol/l) clamp with indirect calorimetry. Muscle biopsies (quadriceps femoris) for the determination of glycogen synthase were performed in 15 patients before and at the end of the clamp.

RESULTS

Insulin infusion reduced the concentrations of IGFBP-1 by 90% (P < 0.001), DHEAS by 11% (P < 0.001), and SHBG by 4% (P < 0.01), whereas free or bound testosterone levels remained unchanged. The fall in IGFBP-1 level was closely related to the basal concentration (r = 0.99, P < 0.001). Basal SHBG concentration correlated directly with total (r = 0.51, P < 0.05) and non-oxidative glucose disposal (r = 0.41, P < 0.05), and with the decrease in lipid oxidation (r = 0.47, P < 0.05) during insulin infusion. The fall in SHBG was inversely related to the mean (30-240 min) FFA concentration during hyperinsulinaemia (r = -0.64, P < 0.001). The fractional activity of glycogen synthase at the end of insulin infusion correlated directly with fasting SHBG (r = 0.71, P < 0.01) and DHEAS concentrations (r = 0.67, P < 0.01).

CONCLUSIONS

In male type 1 diabetic patients: (1) acute hyperinsulinaemia decreases IGFBP-1, DHEAS and SHBG concentrations with the greatest decline in IGFBP-1, (2) SHBG concentration is positively associated with factors indicating good insulin sensitivity, (3) association between fuel homeostasis and SHBG, DHEAS and insulin antagonists suggests a network of these factors in the regulation of insulin action in type 1 diabetic patients.

Effects of gonadal androgens and oestrogens on adrenal androgen levels

OBJECTIVE

The physiological role of adrenal androgens in humans remains unclear. Furthermore, there are few data on the relation between sex steroids and adrenal androgen production. We have assessed the effects of sex steroid hormone administration on adrenal androgen levels, by studying a large group of transsexual patients.

DESIGN

A non-randomized intervention.

SETTING

A university teaching hospital.

PATIENTS

Thirty-one male-to-female and 22 female-to-male transsexual patients.

MEASUREMENTS

Plasma levels of adrenal androgens were measured in a group of male-to-female and female-to-male transsexual patients both before and during cross-gender hormone treatment. This treatment involves administration of testosterone esters to women and of ethinyloestradiol and cyproterone acetate to men.

RESULTS

High dose sex steroid administration had marked effects on adrenal androgens levels, which decreased by 27-48% in males treated with ethinyloestradiol and increased by 23-70% in females treated with testosterone.

CONCLUSION

We conclude that administration of high doses of testosterone and oestradiol exert opposing effects on adrenal androgen production.

Anabolic effects of insulin on bone suggest a role for chromium picolinate in preservation of bone density

Activation of osteoclasts by parathyroid hormone (PTH) is mediated by PTH stimulation of osteoblasts, and is dependent on a PTH-induced rise in protein kinase C activity. Physiological levels of insulin reduce the ability of PTH to activate protein kinase C in osteoblasts, suggesting that insulin may be a physiological antagonist of bone resorption. In addition, insulin is known to promote collagen production by osteoblasts. These findings imply that efficient insulin activity may exert an anabolic effect on bone, and rationalize the many clinical studies demonstrating reduced bone density in Type I diabetes. Recently, the insulin-sensitizing nutrient chromium picolinate has been found to reduce urinary excretion of hydroxyproline and calcium in postmenopausal women, presumably indicative of a reduced rate of bone resorption. This nutrient also raised serum levels of dehydroepiandrosterone-sulfate, which may play a physiological role in the preservation of postmenopausal bone density. The impact of chromium picolinate (alone or in conjunction with calcium and other micronutrients) on bone metabolism and bone density, merits further evaluation in controlled studies.

Hyperinsulinaemia and decreased plasma levels of dehydroepiandrosterone sulfate in premenopausal women with coronary heart disease

OBJECTIVES

The purpose of the study was to establish plasma levels of insulin, ovarian sex hormones and dehydroepiandrosterone sulfate (DHEA-S) and to evaluate their correlations with lipids in premenopausal women with angiographically demonstrated coronary stenosis.

DESIGN

Differences in plasma levels of insulin, ovarian sex hormones, DHEA-S and lipids between groups were compared by analysis of variance.

SETTING

From January 1993 until December 1993 patients were diagnosed in the Outpatient Clinic of the Department of Endocrinology Medical Centre for Postgraduate Education, Warsaw.

SUBJECTS

Premenopausal women with normal oral glucose tolerance test (OGTT) results, with and without coronary stenosis were studied: 21 women after acute myocardial infarction with angiographically demonstrated coronary stenosis (women with CHD), and 14 women with chest pain, a positive exercise test without significant changes of coronary arteries on coronarography (women with normal coronarography, NC). The control group consisted of nine, healthy women with no risk factors for CHD.

MAIN OUTCOME MEASURES

In premenopausal women with CHD, the decreased plasma level of DHEA-S and hyperinsulinaemia were anticipated.

RESULTS

In women with CHD, the plasma levels of DHEA-S (926.5 +/- 83 ng mL-1) were significantly lower than those in women with NC (1375.7 +/- 181 ng mL-1) and in healthy controls (1984 +/- 127 ng mL-1), P < 0.02 and P < 0.001, respectively. The fasting insulin and insulin response to an OGTT in women with CHD and with NC was higher than in healthy subjects. A significant decrease of high-density lipoprotein (HDL) cholesterol, HDL-2 cholesterol and apolipoprotein A-I, and an increase of total cholesterol, low-density lipoprotein cholesterol C and apolipoprotein B levels in women with CHD compared to healthy controls were observed. A negative correlation between fasting insulin and the plasma levels of DHEA-S was established.

CONCLUSION

In premenopausal women, hyperinsulinaemia and decreased DHEA-S levels may contribute to the development of coronary atherosclerosis.

Endogenous sex hormones: impact on lipids, lipoproteins, and insulin

Estrogen use has been reported to decrease triglyceride and low-density lipoprotein cholesterol (LDL-C) and increase high-density lipoprotein cholesterol (HDL-C). Estrogen use increases the secretion of large, very low-density lipoprotein cholesterol (VLDL-C) and also stimulates the uptake of VLDL-C by the liver and increases the catabolism of LDL-C in the liver. Sex hormones may affect several enzymes involved in the metabolism of HDL-C and triglyceride and may also affect lipolysis. In both pre- and postmenopausal women, several studies have shown that increased glucose and insulin concentrations are associated with increased free testosterone and decreased sex hormone binding globulin. The temporal direction of this relationship in premenopausal women is not clear, however. In contrast to women, increased androgen concentrations in men do not seem to be associated with increased cardiovascular risk factors, although testosterone concentrations are associated with increased HDL-C and decreased insulin concentrations. Dehydroepiandrosterone (DHEA) and dehydroepiandrosterone sulfate (DHEAS) appear to be associated with improved cardiovascular risk factors in men, but this connection in women is less clear.

Sex-specific action of insulin to acutely increase the metabolic clearance rate of dehydroepiandrosterone in humans

To test the hypothesis that insulin acutely enhances the metabolic clearance rate (MCR) of dehydroepiandrosterone in humans, the effect of a short-term insulin infusion on the MCR of dehydroepiandrosterone was assessed in 10 men and 7 women. After an overnight fast, dehydroepiandrosterone was infused at 3.47 mumol/h for 6.5 h. At 240 min, a hyperinsulinemic-euglycemic clamp was begun by infusing insulin at 21.5 pmol/kg per min for 2.5 h. MCR of dehydroepiandrosterone was calculated at baseline (210-240 min) and during the insulin infusion (360-390 min). A control study was conducted at least 1 wk later, in which 0.45% saline was substituted for the hyperinsulinemic-euglycemic clamp. During the insulin clamp study, serum insulin rose from 34 +/- 2 to 1084 +/- 136 pmol/liter (P = 0.0001) in men and from 40 +/- 5 to 1357 +/- 175 pmol/liter (P = 0.0003) in women, while serum glucose remained constant in both groups. MCR of dehydroepiandrosterone rose in men during the insulin infusion from 2443 +/- 409 to 3599 +/- 500 liters/24 h (P = 0.003), but did not change during the control saline infusion. In contrast, MCR of dehydroepiandrosterone in women did not change in the insulin clamp study during insulin infusion (2526 +/- 495 liters/24 h at baseline vs. 2442 +/- 491 liters/24 h during insulin infusion; P = 0.78). These findings suggest that insulin acutely increases the MCR of dehydroepiandrosterone in men but not in women.

Altered adrenal and thyroid function in children with insulin-dependent diabetes mellitus

In 129 children, aged 12.6 +/- 3.8 years, affected by type 1 diabetes mellitus, the levels of dehydroepiandrosterone sulfate (DHEAS), cortisol, T3, fT3, T4, fT4, rT3, TSH, cholesterol, and triglycerides were evaluated and compared with those of a control group of 458 healthy age-matched children. The results were also correlated with hemoglobin HbA1C. The DHEAS-standard deviation score (DHEAS-SDS; -0.36 +/- 0.77) was significantly different from zero in diabetic children, while the cortisol serum level was higher than in control subjects (485 +/- 94 vs 359 +/- 132 nmol/l). Moreover, the DHEAS-SDS and DHEAS-SDS/cortisol ratio correlated negatively with HbA1c. Diabetic patients also showed lower T3 values (2.22 +/- 0.4 vs 2.32 +/- 0.3 nmol/l) and a higher rT3/T3 ratio (0.17 +/- 0.09 vs 0.15 +/- 0.05) than controls. There was a negative correlation between T3 and HbA1C. Cholesterol (4.77 +/- 1.08 vs 4.51 +/- 0.76 mmol/l) and triglycerides (0.82 +/- 0.53 vs 0.63 +/- 0.37 g/L) levels were higher in diabetic children and positively correlated with HbA1c, but not with DHEAS-SDS. We can therefore conclude that diabetes, particularly if poorly controlled, tends to induce a dissociation of cortisol and DHEAS secretion and a low T3 syndrome, similar to that seen in other illnesses.