Long-term exposure to dehydroepiandrosterone affects the transcriptional activity of the glucocorticoid receptor

DHEA-pretreatment attenuates oxidative stress in kidney-cortex and liver of diabetic rabbits and delays development of the disease

In view of reported discrepancies concerning antioxidant activity of dehydroepiandrosterone (DHEA), a widely used dietary supplement, the current investigation was undertaken to evaluate the antioxidant properties of DHEA in both kidney-cortex and liver of alloxan (ALX)-induced diabetic rabbits, as this diabetogenic compound exhibits the ROS-dependent action. ALX was injected to animals following 7 days of DHEA administration. Four groups of rabbits were used in the experiments: control, DHEA-treated control, diabetic and DHEA-treated diabetic. Our results show for the first time, that in kidney-cortex DHEA resulted in normalization of hydroxyl free radicals (HFR) levels and restoration of catalase (CAT) and glutathione peroxidase (GPx) activities to near the control values, while in liver DHEA prevented the malondialdehyde (MDA) accumulation and normalized glutathione reductase (GR) and glucose-6-phosphate dehydrogenase (G6PDH) activities. Moreover, in both kidney-cortex and liver DHEA supplementation prevented GSSG elevation accompanied by a decrease in GSH/GSSG ratio. Although DHEA attenuated oxidative stress in both kidney-cortex and liver of ALX-induced diabetic rabbits and significantly delayed the onset of diabetes in time, it did not protect against the final development of diabetes. In conclusion, the current investigation underscores the complexity of the antioxidant action of DHEA. The data are of clinical interest since DHEA supplementation could prevent the deleterious effects of ROS and delay, or even prevent the onset of many diseases. However, in view of the reported pro-oxidant effects of high DHEA doses, the potential use of this agent as a supplement needs a careful evaluation.

Hyperandrogenemia and insulin resistance: The chief culprit of polycystic ovary syndrome

Polycystic ovary syndrome (PCOS) is one of the most common systemic reproductive endocrine diseases, which has a variety of effects on a woman's health. Because of the involvement of multiple pathways and the lack of common clues, PCOS demonstrates multifactorial properties and heterogeneity of symptoms. Recent studies have demonstrated that the core etiology and primary endocrine characteristics of PCOS are hyperandrogenemia (HA) and insulin resistance (IR). HA and IR are the main causes of PCOS and they can interplay each other in the occurrence and development of PCOS. Just because of this, the study about the effects of HA and IR on pathophysiology of various related symptoms of PCOS is very important to understand the pathogenesis of PCOS. This paper reviews the main symptoms of PCOS, including neuroendocrine disorders, reproductive processes, dyslipidemia, obesity, hypertension, nonalcoholic fatty liver disease (NAFLD), and sleep disordered breathing, which seriously affect the physical and mental health of PCOS women. The increasing knowledge of the development pattern of HA and IR in PCOS suggests that changes in diet and lifestyle, and the discovery of potential therapeutic agents may improve PCOS. However, further studies are needed to clarify the mutual influence and relation of HA and IR in development of PCOS. This review provides an overview of the current knowledge about the effects of HA and IR on PCOS.

Dehydroepiandrosterone and Dehydroepiandrosterone-Sulfate and Emotional Processing

Steroid hormones are important regulators of brain development, physiological function, and behavior. Among them, dehydroepiandrosterone (DHEA) and dehydroepiandrosterone-sulfate (DHEAS) also do modulate emotional processing and may have mood enhancement effects. This chapter reviews the studies that bear relation to DHEA and DHEAS [DHEA(S)] and brain emotional processing and behavior. A brief introduction to the mechanisms of action and variations of DHEA(S) levels throughout life has also been forward in this chapter. Higher DHEA(S) levels may reduce activity in brain regions involved in the generation of negative emotions and modulate activity in regions involved in regulatory processes. At the electrophysiological level, higher DHEA-to-cortisol and DHEAS-to-DHEA ratios were related to shorter P300 latencies and shorter P300 amplitudes during the processing of negative stimuli, suggesting less interference of negative stimuli with the task and less processing of the negative information, which in turn may suggest a protective mechanism against negative information overload. Present knowledge indicates that DHEA(S) may play a role in cortical development and plasticity, protecting against negative affect and depression, and at the same time enhancing attention and overall working memory, possibly at the cost of a reduction in emotional processing, emotional memory, and social understanding.

Targeting the HPA axis in major depression: does it work?

In the search for antidepressant drugs with enhanced efficacy, targeting the hypothalamic–pituitary–adrenal (HPA) axis is a valid strategy. This commentary critically summarises the evidence for the efficacy of antidepressant drugs targeting the HPA axis, and concludes that the available clinical trials do not support claims that this class of drugs is superior to existing treatments.

DHEA supplementation to dexamethasone-treated rabbits alleviates oxidative stress in kidney-cortex and attenuates albuminuria

Our recent study has shown that dehydroepiandrosterone (DHEA) administered to rabbits partially ameliorated several dexamethasone (dexP) effects on hepatic and renal gluconeogenesis, insulin resistance and plasma lipid disorders. In the current investigation, we present the data on DHEA protective action against dexP-induced oxidative stress and albuminuria in rabbits. Four groups of adult male rabbits were used in the in vivo experiment: (1) control, (2) dexP-treated, (3) DHEA-treated and (4) both dexP- and DHEA-treated. Administration of dexP resulted in accelerated generation of renal hydroxyl free radicals (HFR) and malondialdehyde (MDA), accompanied by diminished superoxide dismutase (SOD) and catalase activities and a dramatic rise in urinary albumin/creatinine ratio. Treatment with DHEA markedly reduced dexP-induced oxidative stress in kidney-cortex due to a decline in NADPH oxidase activity and enhancement of catalase activity. Moreover, DHEA effectively attenuated dexP-evoked albuminuria. Surprisingly, dexP-treated rabbits exhibited elevation of GSH/GSSG ratio, accompanied by a decrease in glutathione peroxidase (GPx) and glutathione-S-transferase (GST) activities as well as an increase in glucose-6-phosphate dehydrogenase (G6PDH) activity. Treatment with DHEA resulted in a decline in GSH/GSSG ratio and glutathione reductase (GR) activity, accompanied by an elevation of GPx activity. Interestingly, rabbits treated with both dexP and DHEA remained the control values of GSH/GSSG ratio. As the co-administration of DHEA with dexP resulted in (i) reduction of oxidative stress in kidney-cortex, (ii) attenuation of albuminuria and (iii) normalization of glutathione redox state, DHEA might limit several undesirable renal side effects during chronic GC treatment of patients suffering from allergies, asthma, rheumatoid arthritis and lupus. Moreover, its supplementation might be particularly beneficial for the therapy of patients with glucocorticoid-induced diabetes.

The feto-placental unit, and potential roles of dehydroepiandrosterone (DHEA) in prenatal and postnatal brain development: A re-examination using the spiny mouse

Synthesis of dehydroepiandrosterone (DHEA) by the fetal adrenal gland is important for placental oestrogen production, and may also be important for modulating the effects of glucocorticoids on the developing brain. We have preciously shown that the enzymes and accessory proteins needed for DHEA synthesis-cytochrome P450 enzyme 17α-hydroxylase/17,20 lyase (P450c17), cytochrome-b5 (Cytb5), 3β-hydroxysteroid dehydrogenase (3βHSD)-are expressed in the adrenal gland from 30 days gestation, and DHEA, cortisol and aldosterone are present in fetal plasma from this time. Explant culture of fetal adrenal tissue showed that the spiny mouse adrenal gland, can synthesize and secrete DHEA from at least 0.75 of gestation, and suggest that DHEA may have an important role(s) in placental biosynthesis of oestrogens and in modulating the actions of glucocorticoids in the developing brain in this species. Post-natally, increased immuno-expression of P450c17 and Cytb5 expression in the zona reticularis of the adrenal gland and a significant increase in the synthesis and secretion of DHEA in plasma from 8 to 20 days of age in the spiny mouse, are representative of a period of high adrenal androgen production consistent with the human phenomenon of adrenarche. The studies summarised in this review also show that DHEA is produced de novo in the developing brain of the spiny mouse. These results showed that the spiny mouse brain can indeed produce DHEA from pregnenolone in a time-dependant manner, and coupled with the identification of P450c17 and Cytb5 protein in several regions of the brain, support the idea that DHEA is an endogenous neuro-active steroid in this species. Together, the studies outlined in this review indicate that the androgen DHEA is an important hormone of adrenal and Central Nervous System (CNS) origin in the fetal and postnatal spiny mouse. Disturbance of the development of these fetal tissues, and/or of the relationship between the fetal adrenal gland and placenta during pregnancy, may have significant consequences for fetal development, placental function, and maturation of the brain. It is proposed that such disturbances of normal adrenal function could account for some of the neuropathologies that arise in juvenile and adult offspring following illness and stress experienced by the mother during pregnancy.

Ontogenetic Change in the Regional Distribution of Dehydroepiandrosterone-Synthesizing Enzyme and the Glucocorticoid Receptor in the Brain of the Spiny Mouse (Acomys cahirinus)

The androgen dehydroepiandrosterone (DHEA) has trophic and anti-glucocorticoid actions on brain growth. The adrenal gland of the spiny mouse (Acomys cahirinus) synthesizes DHEA. The aim of this study was to determine whether the brain of this precocial species is also able to produce DHEA de novo during fetal, neonatal and adult life. The expression of P450c17 and cytochrome b5 (Cytb5), the enzyme and accessory protein responsible for the synthesis of DHEA, was determined in fetal, neonatal and adult brains by immunocytochemistry, and P450c17 bioactivity was determined by the conversion of pregnenolone to DHEA. Homogenates of fetal brain produced significantly more DHEA after 48 h in culture (22.46 ± 2.0 ng/mg tissue) than adult brain homogenates (5.04 ± 2.0 ng/mg tissue; p < 0.0001). P450c17 and Cytb5 were co-expressed in fetal neurons but predominantly in oligodendrocytes and white matter tracts in the adult brain. Because DHEA modulates glucocorticoids actions, the expression of the glucocorticoid receptor (GR) was also determined. In the brainstem, medulla, midbrain, and cerebellum, the predominant GR localization changed from neurons in the fetal brain to oligodendrocytes and white matter tracts in the adult brain. The change of expression of P450c17, Cytb5 and GR proteins with cell type, brain region and developmental age indicates that DHEA is an endogenous neurosteroid in this species that may have important trophic and stress-modifying actions during both prenatal and postnatal life.

Dehydroepiandrosterone (DHEA): hypes and hopes

Dehydroepiandrosterone (DHEA) and its sulfated form dehydroepiandrosterone sulfate (DHEAS) are the most abundant circulating steroid hormones in humans. In animal studies, their low levels have been associated with age-related involuntary changes, including reduced lifespan. Extrapolation of animal data to humans turned DHEA into a 'superhormone' and an 'anti-aging' panacea. It has been aggressively marketed and sold in large quantities as a dietary supplement. Recent double-blind, placebo-controlled human studies provided evidence to support some of these claims. In the elderly, DHEA exerts an immunomodulatory action, increasing the number of monocytes, T cells expressing T-cell receptor gamma/delta (TCRγδ) and natural killer (NK) cells. It improves physical and psychological well-being, muscle strength and bone density, and reduces body fat and age-related skin atrophy stimulating procollagen/sebum production. In adrenal insufficiency, DHEA restores DHEA/DHEAS and androstenedione levels, reduces total cholesterol, improves well-being, sexual satisfaction and insulin sensitivity, and prevents loss of bone mineral density. Normal levels of CD4+CD25(hi) and FoxP3 (forkhead box P3) are restored. In systemic lupus erythematosus, DHEA is steroid-sparing. In an unblinded study, it induced remission in the majority of patients with inflammatory bowel disease. DHEA modulates cardiovascular signalling pathways and exerts an anti-inflammatory, vasorelaxant and anti-remodelling effect. Its low levels correlate with increased cardiovascular disease and all-cause mortality. DHEA/DHEAS appear protective in asthma and allergy. It attenuates T helper 2 allergic inflammation, and reduces eosinophilia and airway hyperreactivity. Low levels of DHEAS accompany adrenal suppression. It could be used to screen for the side effects of steroids. In women, DHEA improves sexual satisfaction, fertility and age-related vaginal atrophy. Many factors are responsible for the inconsistent/negative results of some studies. Overreliance on animal models (DHEA is essentially a human molecule), different dosing protocols with non-pharmacological doses often unachievable in humans, rapid metabolism of DHEA, co-morbidities and organ-specific differences render data interpretation difficult. Nevertheless, a growing body of evidence supports the notion that DHEA is not just an overrated dietary supplement but a useful drug for some, but not all, human diseases. Large-scale randomised controlled trials are needed to fine-tune the indications and optimal dosing protocols before DHEA enters routine clinical practice.

Is DHEA replacement beneficial in chronic adrenal failure?

Although dehydroepiandrosterone (DHEA) and its sulphate ester dehydroepiandrosterone sulphate (DHEAS) are the most abundant steroid hormones in the human circulation, its exact physiological role is not yet fully understood. In patients with adrenal insufficiency, secretion of DHEA is impaired, leading to decreased circulating DHEA and DHEAS levels, and to androgen deficiency in women. Replacement of DHEA in patients with adrenal insufficiency positively influence mood, sexuality and subjective health status. These effects are generally moderate and show high inter-individual variability. Limited evidence exists for immunomodulatory effects of DHEA. Although an increase of IGF-I levels has been documented, relevant effects on body composition, metabolic or cardiovascular parameters has not been observed in patients with adrenal insufficiency receiving DHEA. Larger-scale phase III studies are still lacking; therefore, initiation of DHEA replacement is decided on an individual basis, focussing on those patients with impaired well-being associated with signs and symptoms of androgen deficiency.

Opposing effects of cortisol and dehydroepiandrosterone on the expression of the receptor for Activated C Kinase 1: implications in immunosenescence

Aging is associated to a decline in immune functions that are in part related to a defective protein kinase C dependent signal transduction machinery. RACK-1 (Receptor for Activated C Kinase 1) is a scaffold protein for different kinases and membrane receptors. We have previously demonstrated, in the elderly, a defective PCKβII (Protein Kinase C βII) translocation related to a decrease in RACK-1 protein expression, which is correlated to the age-associated decline in DHEA (dehydroepiandrosterone) levels. As a consequence of this signal transduction impairment, a significant decrease in immune cells functionality was observed. Furthermore, we could demonstrate that in vivo and in vitro DHEA administration restored RACK-1 level and immune functions, indicating that this hormone behaved as a positive RACK-1 regulator. We have most recently characterized the human GNB2L1 promoter region, coding for RACK-1 protein. Although no direct DHEA responsive elements were found, a glucocorticoid responsive element (GRE) was identified. The purpose of this work was to investigate, in the human pro-myelocytic cell line THP-1, whether physiological cortisol concentrations were able to modulate GNB2L1 promoter activity, RACK-1 transcription as well as cytokine production. As DHEA is endowed of anti-glucocorticoid properties in several cellular systems, and as cortisol:DHEA ratio imbalance is relevant in aging, we also investigated their possible interaction at the RACK-1 expression level. We could demonstrate that cortisol acted in a dose-related manner as a GNB2L1 promoter repressor, reducing RACK-1 mRNA expression and protein level. Probably by interfering with glucocorticoid receptor binding to GRE sequence, prolonged DHEA exposure counteracted cortisol effects, restoring RACK-1 levels and cytokine production, as assessed by LPS-induced TNF-α release.

A potential role for 5-androstene-3β,7β,17β-triol in obesity and metabolic syndrome

Metabolic syndrome is marked by perturbed glucocorticoid (GC) signaling, systemic inflammation, and altered immune status. Dehydroepiandrosterone (DHEA), a major circulating adrenal steroid and dietary supplement, demonstrates antiobesity, anti-inflammatory, GC-opposing and immune-modulating activity when administered to rodents. However, plasma DHEA levels failed to correlate with metabolic syndrome and oral replacement therapy provided only mild benefits to patients. Androstene-3β,7β,17β-triol (β-AET) an anti-inflammatory metabolite of DHEA, also exhibits GC-opposing and immune-modulating activity when administered to rodents. We hypothesized a role for β-AET in obesity. We now report that plasma levels of β-AET positively correlate with BMI in healthy men and women. Together with previous studies, the observations reported here may suggest a compensatory role for β-AET in preventing the development of metabolic syndrome. The β-AET structural core may provide the basis for novel pharmaceuticals to treat this disease.

Steroidal and gonadal effects on neural cell proliferation in vitro in an adult songbird

Neurogenesis in the adult songbird brain occurs along the ventricular zone (VZ), a specialized cell layer surrounding the lateral ventricles. To examine the acute effects of sex steroids on VZ cell proliferation, male and female adult zebra finch brain slices containing the VZ were exposed to 5-bromo-2'-deoxyuridine-5'-monophosphate (BrdU) in vitro. Slices from one hemisphere served as the control, while contralateral slices were treated with steroids, steroidogenic enzyme inhibitors or gonadal tissue itself. There were no significant effects on VZ cell proliferation in either sexes by acute exposure to 17beta-estradiol (E2), dihydrotestosterone (DHT), a cocktail of four sex steroids, and inhibitors of sex steroid synthesis (aminoglutethimide, ketoconazole, and fadrozole), or by activation of a mitochondrial cholesterol transporter. By contrast, dehydroepiandrosterone (DHEA) suppressed VZ cell proliferation in males, but not females, replicating previous observations involving treatments with corticosterone and RU-486. This suggests that DHEA suppresses proliferation in males via a glucocorticoid receptor-related mechanism. These results suggest that neurosteroidogenesis per se has little effect on acute VZ cell proliferation. Co-incubation with an ovary of female, but not male, slices significantly increased VZ cell proliferation; testicular tissue had no impact on proliferation in males or females. This suggests a role for a non-steroidal ovarian factor on adult female VZ cell proliferation. We also have evidence that previously reported sex-differences in BrdU-labeling along the adult VZ (males>females) result from a more rapid loss of cells in females. Sex differences in steroid action and cell death along the VZ may contribute to the maintenance of the sexually dimorphic song system.

Age, body mass index, and serum level of DHEA-S can predict glucocorticoid receptor function in women with polycystic ovary syndrome

Glucocorticoid receptor (GR) transduces the glucocorticoid (GC) signal that could lead to metabolic derangements depending on the tissue responsiveness to GC. We aimed to investigate possible causative relation of the GR functional properties in peripheral blood mononuclear cells of women with polycystic ovary syndrome (PCOS), with their clinical and biochemical characteristics. Thirty women with PCOS [mean age: 26.5 ± 5.1 years, mean body mass index (BMI) 24.5 ± 5 kg/m(2)], and thirty respective controls were analyzed for the number of GR sites per cell (B (max)), apparent equilibrium dissociation constant (K (d)), and binding potency (GR potency). A strong association between B (max) and K (d) (r = 0.70, P < 0.0001), and GR potency with age (r = 0.49, P = 0.009) was observed in PCOS women. The multiple regression analyses within the PCOS group revealed that independent predictors for K (d) were BMI, total cholesterol, and dehydroepiandrosterone-sulfate (DHEA-S) (r = 0.58, P = 0.038), while for GR potency (r = 0.687, P = 0.013) were age, BMI, DHEA-S, and basal cortisol concentration. The results suggest that PCOS pathophysiology may be related to alterations of a cross stalk between glucocorticoid signaling, age, and metabolic parameters. These findings should be further explored in studies on the role of GR in PCOS-related metabolic derangements.

Synergistic effects of dehydroepiandrosterone and fluoxetine on proliferation of progenitor cells in the dentate gyrus of the adult male rat

The 5-HT re-uptake inhibitor (SSRI) fluoxetine and the adrenal hormone dehydroepiandrosterone (DHEA) both increase the proliferation of progenitor cells in the adult hippocampus and also have antidepressant activity. This paper explores the combined ability of fluoxetine and DHEA to affect this process in the dentate gyrus of adult rats. We show that DHEA can render an otherwise ineffective dose of fluoxetine (2.5 mg/kg) able to increase progenitor cell proliferation to the same extent as doses four times higher (10 mg/kg). This synergistic action does not appear to be mediated by alterations in brain-derived neurotrophic factor (BDNF) gene expression; or by TrkB, mineralocorticoid, glucocorticoid, or 5-HT (5HT1A) receptor expression in the dentate gyrus; or by altered levels of plasma corticosterone. In a second experiment, the synergism between DHEA and fluoxetine was replicated. Furthermore, flattening the diurnal rhythm of plasma corticosterone by implanting additional corticosterone pellets s.c. prevented the effect of fluoxetine on progenitor cell division. This was not overcome by simultaneous treatment with DHEA, despite the latter's reported anti-glucocorticoid actions. The cellular mechanism for the potentiating action of DHEA on the pro- proliferative effects of fluoxetine in the adult hippocampus remains to be revealed. Since altered neurogenesis has been linked to the onset or recovery from depression, one consequence of these results is to suggest DHEA as a useful adjunct therapy for depression.

Leukemia inhibitory factor protein and receptors are expressed in the bovine adrenal cortex and increase cortisol and decrease adrenal androgen release

The release of adrenal steroids during acute stress is primarily regulated by adrenocorticotropic hormone (ACTH). In contrast, during chronic inflammatory stress additional factors are involved in regulating adrenal function. Leukemia inhibitory factor (LIF) is a pleiotropic cytokine that increases ACTH release from the pituitary. In addition, LIF and LIF receptors (LIFR) are expressed in the human adrenal cortex and the human adrenocortical tumor cell line H295R. Furthermore, LIF increases basal and ACTH-stimulated cortisol release from H295R cells. However, the expression of LIF and LIFR in non-human adrenal glands and the effects of LIF on the release of cortisol from adrenal cells of non-human species have not been determined. Furthermore, the effects of LIF on adrenal androgen release from all species are unknown. In this study, immunohistochemistry, Western blots, RT-PCR, and nucleotide sequencing was utilized to demonstrate that LIF and its receptor are expressed throughout the bovine adrenal cortex. Although LIF did not modify basal cortisol release from dispersed cells isolated from the bovine adrenal zona fasciculate, this cytokine increased ACTH-stimulated release of cortisol from these cells in a manner dependent on the LIF concentration and exposure interval. In contrast, LIF in a concentration-dependent and time-dependent manner decreased basal and ACTH-stimulated adrenal androgen release from dispersed cells isolated from the bovine adrenal zona reticularis. Because LIF release increases during inflammatory stress and this cytokine stimulates adrenal cortisol release and inhibits adrenal androgen release, this cytokine may play an important role in regulating the release of adrenal steroids during inflammatory stress.

Interleukin-4 increases cortisol release and decreases adrenal androgen release from bovine adrenal cells

ACTH is the primary regulator of adrenal function during acute stress. However, during chronic inflammatory stress additional factors play a major role in the regulation of adrenal secretion. Many cytokines circulate in the blood and are synthesized and released from adrenal tissue. Furthermore, these peptides modify adrenal function. Recently, interleukin-4 (IL-4) was demonstrated to be released from a human adrenal tumor cell line. Therefore, we hypothesized that normal bovine adrenocortical cells could express IL-4 and that this cytokine may modify adrenal function. We determined that IL-4 and IL-4 receptors (IL-4R) are expressed in the bovine adrenal cortex whereas the expression of IL-4 and IL-4R in the adrenal medulla was not apparent. Exposure of dispersed bovine adrenocortical cells isolated from the zona fasciculate to IL-4 did not modify basal release of cortisol. However, the ACTH-stimulated release of cortisol from the bovine adrenal cells was augmented by IL-4. IL-4 exposure had no affect on adrenal androgen release from bovine zona reticularis cells, but IL-4 inhibited the ACTH-stimulated release of adrenal androgens from these cells. The effects of IL-4 on ACTH-stimulated cortisol and adrenal androgen release were dependent upon the IL-4 incubation interval and the IL-4 concentration. Because communication between the immune and endocrine systems is important in inflammatory conditions, IL-4 may play a role in coordinating the adrenal response to inflammatory stress.