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Effect of dehydroepiandrosterone (DHEA) on intestinal mucosal immunity in young adult and aging rats.

The present study assesses the effectiveness of oral DHEA on the intestinal mucosal immune response in aging rats. Young adult (6 months) and aging (21 months) female rats received powdered rat chow with or without 0.2% DHEA for 23 days. The animals were immunized intraduodenally with either cholera toxin (CTx) or vehicle alone and boosted two weeks later. Seven days after boosting, serum, bile, small intestinal tissue, and liver were collected for analysis. Anti-CTx IgA antibody titers were measured in serum and bile and the concentration of anti-CTx antibody containing cells (ACCs) in the small intestinal lamina propria and liver were determined by quantitative immunohistochemistry. Intergroup comparisons indicated that there was only one significant difference in serum and none in bile anti-CTx IgA titers between CTx-immunized animals fed DHEA or the diet alone. Immunohistochemical analysis determined that the density and distribution patterns of ACCs within the lamina propria were unaffected by DHEA. Both DHEA-treated and control young immunized animals exhibited similar numbers of ACCs. Only 40% of the aging rats responded to intraduodenal immunization with CTx, as determined by the presence of ACCs in the intestine, regardless of the presence or absence of DHEA in the diet. These data suggest that DHEA in the diet does not enhance the intestinal mucosal immune response to intraduodenal CTx in either young adult or aging rats.

Adjuvants, Immunologic↗

Effect of estradiol on DHEAS production in the human adrenocortical cell line, H295R.

OBJECTIVE: To determine if estradiol regulates DHEA and DHEAS production in a human adrenocortical (H295R) cell line and to determine if this effect is receptor mediated. METHODS: NCI-H295 (H295R) cells were rinsed and placed in phenol red free Dulbecco's Modified Eagle's-F12 medium supplemented with 0.1% charcoal-stripped serum. After 24 hours, cells were rinsed and treated based on experimental design. The effects of estradiol were investigated by: 1) treatment of cells with increasing concentrations of estradiol (300-3000 nmol/L) with or without forskolin (10 mumol/L), 2) treatment of cells with the nonsteroidal synthetic estrogen diethylstilbestrol (DES) (300-3000 nmol/L) with or without forskolin (10 mumol/L), and 3) treatment of cells with an estradiol antagonist (ICI 182, 780) in the presence of estradiol. RESULTS: Estradiol alone increased the basal production of DHEAS in H295R cells in a concentration-dependent manner with a maximal effect at 1000 nmol/L. Forskolin treatment increased the basal production of DHEAS ten-fold. Estradiol also increased the forskolin stimulation of DHEAS production two-fold. In contrast, DES alone or DES in addition to forskolin did not stimulate DHEAS production. Estradiol, in contrast, inhibited H295R adrenal cell production of cortisol whereas DES exhibited a similar inhibition. The estrogen receptor antagonist ICI 182,780 was unable to inhibit the stimulatory effect of estradiol. Finally, estradiol in a concentration-dependent manner suppressed 3 beta-hydroxysteroid dehydrogenase (3 beta HSD) activity in H295R adrenal cells. CONCLUSION: These experiments support the role of estradiol in regulation DHEAS production by inhibiting 3 beta HSD activity; however, the mechanism appears to require high concentrations of estradiol and appears to be independent of the estrogen receptor.

3-Hydroxysteroid Dehydrogenases↗

Evidence for the involvement of the fatty acid and peroxisomal beta-oxidation pathways in the inhibition by dehydroepiandrosterone (DHEA) and induction by 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) and benz(a)anthracene (BA) of cytochrome P4501B1 (CYP1B1) in mouse embryo fibroblasts (C3H10T1/2 cells).

Treatment of intact C3H10T1/2 cells or microsomes therefrom with 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) and benzanthracene (BA) enhanced CYP1B1 activity and CYP1B1 expression as revealed by elevations of CYP1B1-catalyzed DMBA metabolism, CYP1B1 apoprotein level and CYP1B1 gene expression. One hundred microM DHEA caused an 80-90% inhibition of cellular DMBA metabolism without inflicting cell death. Cytosolic glucose-6-phosphate dehydrogenase (G6PDH) was also inhibited in DHEA-treated cells, presumably due to the inhibition of NADP reduction. In contrast, neither DMBA metabolism nor CYP1B1 apoprotein was inhibited by DHEA in the microsomes isolated from these cells. DHEA (100 microM), TCDD (10 nM) and BA (10 microM) stimulated the activities and increased the apoprotein levels of two peroxisomal enzymes, namely, acyl CoA oxidase (ACOX) and acyl CoA hydrolase (ACH2) and also induced the expression of CYP1B1 and ACOX genes. Cytosolic fatty acyl-CoA beta-oxidation was also stimulated by DHEA, TCDD and BA. In corroboratory experiments, it was found that concomitant with the stimulation of the activity of a key enzyme regulator of fatty acid homeostasis, namely, glycerol-3-phosphate dehydrogenase (G3PDH), these agents enhanced arachidonic acid (AA) metabolism as judged by the release of [3H] from AA into the culture medium. Collectively, these data suggest that DHEA mediates the regulation of CYP1B1 and inhibits BA and TCDD-induced CYP1B1-catalyzed carcinogen (DMBA) activation in 10T1/2 cells through metabolic interactions that involve the activation of the peroxisomal and fatty acid beta-oxidation signaling pathways. These results also present evidence for the first time, for the possible peroxisomal effects of TCDD and BA which are similar to those of DHEA in this mouse embryo fibroblast cell line.

9,10-Dimethyl-1,2-benzanthracene↗

Effects of the chronic use of dehydroepiandrosterone (DHEA) on testicular weight and spermatogenesis: experimental study in rats.

AIM: The complete biological effects of chronic use of dehydroepiandrosterone (DHEA), reported as a weak androgen, are not completely understood. The aim of the present study is to evaluate the effects of chronic administration of DHEA on the spermatogenesis in rats. METHODS: Male Wistar rats, 4 months old, were selected for the study. The animals were divided into two groups. Group 1 (n = 9) received placebo (saline solution) 0.5 ml/day and Group 2 (n = 15) received DHEA 5 mg/kg/day. Both the groups received the respective treatments 5 days a week during 10 months. At the end of the exposure, the rats were sacrificed and the testes removed, weighed and processed for histologic analysis. Spermatogenesis was evaluated as the mean number of seminiferous tubules with and without spermatids in maturation phase in their lumen, in five random fields on the same slide. RESULTS: The median levels of serum total testosterone and dehydroepiandrosterone sulfate was measured in the two groups. Significant higher concentrations in total testosterone (2.06 +/- 0.4 vs. 0.80 +/- 0.2; p < 0.05) and DHEAS (222.1 +/- 41.5 vs. 2.0 +/- 0.3) were observed in the group treated with DHEA as compared to the control group. The mean weights of the right testes were 1.59 +/- 0.3 in group 1 and 1.58 +/- 0.2 g in group 2 (p > 0.05). These values for the left testes were 1.57 +/- 0.3 and 1.55 +/- 0.3 g, respectively (p > 0.05). The histologic analysis showed a mean of 13.5 +/- 1.5 and 12.8 +/- 1.8 seminiferous tubules per field in the groups 1 and 2, respectively (p > 0.05). The same analysis demonstrated that in the control group 0.06 +/- 0.1 of the tubules presented without spermatids in maturation phase and in the DHEA group this was observed in 0.22 +/- 1.2 of the tubules (p > 0.05). CONCLUSION: Chronic administration of DHEA in the present dose did not show any detectable effect on the quantitative and qualitative analyses of spermatogenesis in rats.

Animals↗

The influence of age and gender on serum dehydroepiandrosterone sulphate (DHEA-S), IL-6, IL-6 soluble receptor (IL-6 sR) and transforming growth factor beta 1 (TGF-beta1) levels in normal healthy blood donors.

Dysregulation of IL-6 synthesis is thought to play a role in the development of a number of age-related conditions, such as rheumatoid arthritis, osteoporosis, atherosclerosis, Alzheimer's disease and B cell malignancies. Recently it has been suggested that the production of IL-6 is influenced by the adrenal hormone dehydroepiandrosterone (DHEA) and its sulphated derivative DHEA-S. In humans we investigated the relationship between DHEA-S, IL-6, IL-6 sR and TGF-beta1 in the serum of normal healthy male and female blood donors. Using immunoassay techniques we found that the serum levels of DHEA-S significantly (P = 0.0001) decreased with age in both males and females. Furthermore, mean DHEA-S levels in all age groups were significantly (P = 0.0001) higher in males. Such correlations were not apparent for IL-6 using a standard assay, but a high sensitivity assay revealed that serum IL-6 was significantly (P = 0.0018) positively correlated with age in males only. In addition, serum levels of DHEA-S were significantly (P = 0.048) negatively correlated with serum IL-6, again in male subjects only. In contrast, serum IL-6 sR and TGF-beta1 levels were not correlated with age in either males or females and were not significantly different between the sexes. However, a significant (P = 0.024) negative correlation between DHEA-S and IL-6 sR was found in males. These studies clearly highlight the complex nature of the relationship between these molecules in the ageing process in normal healthy blood donors and demonstrate the need to use high sensitivity assays when measuring IL-6 in apparently healthy individuals under the age of 70 years.

Adolescent↗

Dehydroepiandrosterone (DHEA) stimulates neurogenesis in the hippocampus of the rat, promotes survival of newly formed neurons and prevents corticosterone-induced suppression.

Treating adult male rats with subcutaneous pellets of dehydroepiandrosterone (DHEA) increased the number of newly formed cells in the dentate gyrus of the hippocampus, and also antagonized the suppressive of corticosterone (40 mg/kg body weight daily for 5 days). Neither pregnenolone (40 mg/kg/day), a precursor of DHEA, nor androstenediol (40 mg/kg/day), a major metabolite, replicated the effect of DHEA (40 mg/kg/day). Corticosterone reduced the number of cells labelled with a marker for neurons (NeuN) following a 28-day survival period, and this was also prevented by DHEA. DHEA by itself increased the number of newly formed neurons, but only if treatment was continued throughout the period of survival. Subcutaneous DHEA pellets stimulated neurogenesis in a small number of older rats ( approximately 12 months old). These results show that DHEA, a steroid prominent in the blood and cerebral environment of humans, but which decreases markedly with age and during major depressive disorder, regulates neurogenesis in the hippocampus and modulates the inhibitory effect of increased corticoids on both the formation of new neurons and their survival.

Age Factors↗

Dehydroepiandrosterone (DHEA) levels in patients with prostatic cancer, heart diseases and under surgery stress.

DHEA levels in patients with prostatic cancer were significantly lower, but total and free testosterone (T) significantly higher as those in an age-matched control group. Therefore, the calculated quotients DHEA/free T and DHEA/T were especially different between both groups. DHEA and DHEAS levels in patients with heart diseases were also significantly lower but cortisol (F) levels were significantly higher as those in a control group. The quotients DHEA/F and DHEAS/F were also of greater significance between both groups than the hormone values alone. The response of DHEA and F levels in patients undergoing surgery showed an increase of both steroids under surgery. On the second postoperative day, however, F levels were still significantly higher but DHEA levels were significantly lower as the initial values. The differences between the initial values and those on the second postoperative day of F and DHEA showed a significant correlation, i.e. the higher the elevation of F levels above the initial values the greater was the diminution of DHEA levels below the initial values.

Adult↗

Cortisol, DHEA, performance and training in elite swimmers.

Salivary cortisol (C) and DHEA concentrations were measured in 9 elite swimmers (4 female and 5 male) over a 37-week period, 5 to 12 times per swimmer, before 68 competitions. For female and male swimmers, no significant relationship was found between C, DHEA and performance. For the whole group, C was negatively correlated with week number of training (r = -0.31, p < 0.01). The incorporation of the cumulated distance swum as a second variable in the regression increased r to 0.56 (p < 0.01). The higher the cumulated distance swum, the higher C. No significant relationship was found between DHEA and distance swum. For individual swimmers, 3 of 4 females showed a significant negative relationship between C and cumulated dry-land training. No equivalent relationship was found for DHEA. The 2 males practicing dry-land training showed a significant and negative relationship between DHEA and cumulated dry-land training. No equivalent relationship was found for C. Thus, C and DHEA were not good predictors of swimming performance. C for individual females, and DHEA for individual males were considered useful markers for dry-land training stress.

Adolescent↗

Activation of human monocytes by LPS and DHEA.

Dehydroepiandrosterone (DHEA) alone, whatever the concentration used, or lipopolysaccharide (LPS) alone at 0.2 ng/ml did not induce the release of interleukin-6 (IL-6) or tumor necrosis factor (TNF) by human monocytes. However DHEA (10[-9] M or 10[-12] M) in association with LPS (0.2 ng/ml) did induce the release of IL-6 and TNF. When human monocytes were activated by 1 microg/ml LPS, both IL-6 and TNF secretions were observed. Monocytes activated by both DHEA (10[-9] M or 1O[-12] M) and LPS (1 microg/ml) secreted IL-6 and TNF at a higher level than that observed for monocytes activated only by LPS (1 microg/ml) alone. DHEA alone, whatever the concentration used, or LPS alone at 0.2 ng/ml did not induce the activation of mitogen-activated protein kinases (MAPkinases) and protein kinase C (PKC) or the expression of c-fos and c-jun. However DHEA (10[-9] M or 10[-12] M) and 0.2 ng/ml LPS together induced the activation of both MAPKinases and PKC and the expression of c-fos and c-jun. Furthermore, the activation of PKC and MAPKinases and the expression of c-fos and c-jun were much greater when human monocytes were activated by both LPS (1 microg/ml) and DHEA (10[-9] M or 10[-12] M) than when the monocytes were activated only by LPS at 1 microg/ml. Therefore, DHEA and LPS displayed a synergistic effect on monocyte activation.

Calcium-Calmodulin-Dependent Protein Kinases↗

Supplementation with DHEA: effect on muscle size, strength, quality of life, and lipids.

OBJECTIVE: To evaluate the effects of combination estrogen/androgen therapy on muscle mass, strength and endurance, serum hormone and lipid profiles, and quality of life measures in postmenopausal women. METHODS: Prospective, randomized, placebo-controlled pilot study at a tertiary care medical center. Fifty postmenopausal women were randomized to a 12-week course of (1) dehydroepiandrostenedione (DHEA) 50 mg daily, (2) conjugated equine estrogen (CEE) 0.625 mg daily, (3) DHEA 50 mg+CEE 0.625 mg daily, or (4) placebo. Main outcome measures of lower extremity muscle (calf) mass, functional muscle parameters, serum hormone and lipid levels, and quality of life (QOL) were obtained at baseline and after treatment. Statistical analysis compared percent change from baseline values and treatment differences among outcomes. RESULTS: Significant increases in mean DHEA, DHEA sulfate (DHEA-S), testosterone, and androstenedione levels were noted with DHEA alone or combined DHEA/CEE treatments when compared with placebo. Compared with no hormone therapy, none of the supplemental hormone groups caused significant changes in muscle mass, muscle strength, muscle endurance, feelings of well-being, sleep, or sexual function. CONCLUSIONS: Androgen replacement therapy, with DHEA, to menopausal women increases serum androgen levels without any appreciable effect on muscle cross-sectional area, muscle strength, muscle function, or improvement in health-related QOL.

Aged↗

Effect of dehydroepiandrosterone (DHEA) on the metabolism of 7,12-dimethylbenz[a]anthracene (DMBA) in rats.

The influence of dehydroepiandrosterone (DHEA), an adrenal steroid, on the biotransformation of the carcinogen 7,12-dimethylbenz[a]anthracene (DMBA) in rats has been investigated. Male Sprague-Dawley rats (2-3 months old) were fed DHEA for 14 days at a dietary level of 0.8%. There was an increase in liver weights with increases per whole liver, in total protein, microsomal and cytosolic protein and cytochrome P-450, and cytosolic glutathione transferase activity in DHEA fed rats. DNA content of the liver, however, remained constant. Forty-eight hours after a single i.p. dose of [3H]DMBA (133 mumol/kg body weight, 102 muCi/rat) binding of DMBA derived metabolites to DNA decreased significantly both per unit of DNA (605 versus 194 pmol/mg DNA) as well as per whole liver DNA (25.4 versus 8.5 nmol) in DHEA fed rats. However, a significantly higher amount of DMBA-derived metabolites were bound to total hepatic protein (455 versus 288 nmol) in the steroid fed rats. Microsome mediated binding of DMBA to DNA was 3-fold higher in DHEA fed rats. Excretion of DMBA-derived metabolites in urine was 2-fold higher in DHEA fed rats. The results of this study demonstrate that DHEA inhibits binding of DMBA to hepatic DNA in vivo in spite of the increased metabolic activation of the carcinogen perhaps due to increased detoxification and competitive binding of its active species to proteins.

9,10-Dimethyl-1,2-benzanthracene↗

Seizure frequency and cortisol and dehydroepiandrosterone sulfate (DHEAS) levels in women with epilepsy receiving antiepileptic drug treatment.

PURPOSE: Hormonal changes occur in epilepsy because of seizures themselves and of antiepileptic drug (AED) effects on steroid production, binding, and metabolism. Conversely, steroids may influence neuron activity and excitability by acting as neuroactive steroids. This cross-sectional observational study aimed to evaluating cortisol and dehydroepiandrosterone sulfate (DHEAS) levels in female epilepsy patients with different disease severity, as assessed by a seizure frequency score (SFS). METHODS: Morning serum levels of cortisol and DHEAS were assayed in 113 consecutive women, aged 16 to 47 years, with varied epilepsy syndromes, receiving mono- or polytherapy with enzyme-inducing and/or noninducing antiepileptic drugs (AEDs). Hormonal data were correlated with clinical parameters (age, body mass index, epilepsy syndrome, disease onset and duration, SFS, AED therapy, and AED serum levels) and compared with those of 30 age-matched healthy women. RESULTS: In epilepsy patients, cortisol levels and cortisol-to-DHEAS ratios (C/Dr) were significantly higher, whereas DHEAS levels were significantly lower than those in controls. Patients with more frequent seizures showed higher cortisol and C/Dr values and lower DHEAS levels than did those with rarer or absent seizures during the previous 6 months. SFS mainly explained the increase of cortisol levels and C/Dr in patients with more active disease. Changes in DHEAS levels correlated with SFS and epilepsy syndrome, as well as with AED treatments and ages. CONCLUSIONS: Women with more frequent seizures had alterations of their adrenal steroids characterized by an increase of cortisol and a decrease of DHEAS levels. Such hormonal changes might be relevant in seizure control and in patient health.

Adolescent↗

The sex steroid precursor DHEA accelerates cutaneous wound healing via the estrogen receptors.

Age-related impaired wound healing states lead to substantial morbidity and cost, with treatment in the USA resulting in an expenditure of over $9 billion per annum. Dehydroepiandrosterone (DHEA) is a ubiquitous adrenal hormone with immunomodulatory properties whose levels decline significantly with advanced age in humans. Conversion of DHEA locally to downstream steroid hormones leads to estrogenic and/or androgenic effects which may be important in age-related skin homeostasis, and which would avoid systemic adverse effects related to estrogen. We report that systemic DHEA levels are strongly associated with protection against chronic venous ulceration in humans. DHEA accelerated impaired healing in an impaired healing model (mice rendered hypogonadal) associated with increased matrix deposition and dampens the exaggerated inflammatory response. Such effects were mediated by local conversion of DHEA to estrogen, acting through the estrogen receptor, and vitro studies suggest a direct effect on specific pro-inflammatory cytokine production by macrophages via mitogen activated kinase (MAP) and phosphatidylinositol 3 (PI3) kinase pathways. In addition, we show that local injection of DHEA accelerates impaired healing in an ageing mouse colony. We suggest that exogenous application of DHEA accelerates impaired wound repair, results which may be applicable to the prophylaxis and treatment of human impaired wound healing states.

Aging↗

Dehydroepiandrosterone (DHEA) replacement reduces growth hormone (GH) dose requirement in female hypopituitary patients on GH replacement.

OBJECTIVE: GH dose requirement is lower in ACTH replete compared with ACTH deficient hypopituitary patients suggesting that adrenal androgens may augment IGF-I generation for a given GH dose. This study aimed to determine the effect of dehydroepiandrosterone (DHEA) administration on GH dose requirements in hypopituitary adults. DESIGN: A double blind placebo controlled trial was conducted adding 50 mg DHEA to the standard replacement of hypopituitary patients, including GH, over an initial 6 months, followed by an open phase study of 6 months DHEA replacement and a final 2 month washout phase after DHEA withdrawal. The dose of GH was adjusted to achieve a constant serum IGF-I. PATIENTS: Thirty female and 21 male hypopituitary patients were enrolled. Data from 26 women and 18 men were analysed after patient withdrawal. MEASUREMENTS: The primary outcome objective was the GH dose required to achieve a stable serum IGF-I. Secondary outcome measures were lipoprotein profiles, insulin, insulin sensitivity, IGFBP-3, waist/hip ratio and indices of bone remodelling. RESULTS: DHEA replacement in female patients lead to a 14.6 +/- 20% reduction in the dose of GH for a constant serum IGF-I (P < 0.05, 95% CI: 1.8, 32.7). This was maintained for 12 months and there was a significant fall in serum IGF-I two months after withdrawal of DHEA. There was no change in the male group. CONCLUSIONS: DHEA replacement may reduce GH dose requirements in female hypopituitary patients.

Adult↗

Raised cortisol:DHEAS ratios in the elderly after injury: potential impact upon neutrophil function and immunity.

The detrimental effect of stress on the immune response increases with age, though the mechanisms responsible are not fully understood. The physiological response to stress is regulated in part by the adrenocortical system. Adrenal hormones dehydroepiandrosterone sulphate (DHEAS) and cortisol have opposing effects on the innate immune system, DHEAS enhances while cortisol suppresses immunity and the molar ratio of cortisol to DHEAS increases with age. We found that elderly hip fracture patients produced a robust neutrophilia after injury, but circulating neutrophils showed an impaired antibacterial response. We therefore proposed that adrenocortical hormones mediate the heightened immunosuppression seen in the elderly after injury. We examined neutrophil function and adrenocortical hormone levels in elderly (> 65 years) hip fracture patients and age-matched healthy controls. Thirteen out of 35 elderly patients acquired infections following hip fracture. Neutrophil superoxide production was lower in elderly hip fracture patients compared with controls (P < 0.005) and lower in patients who acquired infection following injury compared with those who did not (P < 0.05). Serum cortisol:DHEAS ratio was higher in elderly hip fracture patients (0.56 +/- 0.38) compared with either age-matched controls (0.36 +/- 0.21; P < 0.05) or young fracture patients (0.087 +/- 0.033; P < 0.0001). Moreover, cortisol: DHEAS was increased in elderly patients who succumbed to infection compared with those who did not (0.803 +/- 0.42 vs. 0.467 +/- 0.28; P < 0.02). In vitro cortisol significantly decreased neutrophil superoxide generation (P < 0.05) and this was prevented by coincubation with DHEAS. We propose that increased cortisol:DHEAS ratios may contribute to reduced immunity following physical stress in the elderly.

Aged↗

The epidemiology of DHEAS and cardiovascular disease.

In 1986 we reported that high levels of plasma dehydroepiandrosterone sulfate (DHEAS) reduced the risk of fatal cardiovascular disease (CVD) in 242 men and increased the risk in 289 women from the Rancho Bernardo cohort who were followed up for 12 years. We report here an update on the epidemiology of DHEAS and CVD based on a 19-year follow-up of 1,029 men and 942 women aged 30-88 years from the same cohort. In cross-sectional analyses, DHEAS levels decreased with age in both sexes and were lower in women than men. Men who were overweight were more likely to have low DHEAS levels; women who had hypercholesterolemia or hypertension or were nonusers of estrogen therapy had higher DHEAS levels. Alcohol intake and cigarette smoking were associated with higher DHEAS levels in both sexes. All differences were no longer statistically significant after adjusting for alcohol intake. All participants were followed for vital status. After 19 years there were 254 CVD deaths in men and 199 CVD deaths in women. DHEAS was not associated with CVD or ischemic heart disease (IHD) deaths in age-adjusted analyses where the comparison group was individuals without CVD or IHD death. In contrast, when the comparison group was survivors, multiply adjusted models showed a statistically significant, modestly reduced risk of fatal CVD (RR = 0.85) in men and a nonsignificant increased risk of fatal CVD (RR = 1.11) in women.

Adult↗

DHEA administration increases rapid eye movement sleep and EEG power in the sigma frequency range.

Dehydroepi-androsterone (DHEA) exhibits various behavioral effects in mammals, at least one of which is enhancement of memory that appears to be mediated by an interaction with the gamma-aminobutyric acidA (GABAA) receptor complex. We investigated the effects of a single oral dose of DHEA (500 mg) on sleep stages, sleep stage-specific electroencephalogram (EEG) power spectra, and concurrent hormone secretion in 10 healthy young men. DHEA administration induced a significant (P < 0.05) increase in rapid eye movement (REM) sleep, whereas all other sleep variables remained unchanged compared with the placebo condition. Spectral analysis of five selected EEG bands revealed significantly (P < 0.05) enhanced EEG activity in the sigma frequency range during REM sleep in the first 2-h sleep period after DHEA administration. In contrast, the EEG power spectra of non-REM sleep were not affected, nor were the nocturnal time course curves of plasma cortisol, growth hormone, or testosterone concentration. The results suggest that DHEA administration has a mixed GABAA-agonistic/antagonistic effect, exerted either directly or through DHEA-induced changes in steroid metabolism. Because REM sleep has been implicated in memory storage, its augmentation in the present study suggests the potential clinical usefulness of DHEA in age-related dementia.

Adult↗

DHEA protects against visceral obesity and muscle insulin resistance in rats fed a high-fat diet.

Visceral obesity is frequently associated with muscle insulin resistance. Rats fed a high-fat diet rapidly develop obesity and insulin resistance. Dehydroepiandrosterone (DHEA) has been reported to protect against the development of obesity. This study tested the hypothesis that DHEA protects against the increase in visceral fat and the development of muscle insulin resistance induced by a high-fat diet in rats. Feeding rats a diet providing 50% of the energy as fat for 4 wk resulted in a twofold greater visceral fat mass and a 50% lower rate of maximally insulin-stimulated muscle 2-deoxyglucose (2-DG) uptake compared with controls. Rats fed the high-fat diet plus 0.3% DHEA were largely protected against the increase in visceral fat (+ 11.3 g in high fat vs. + 2.9 g in high fat plus DHEA, compared with controls) and against the decrease in insulin-stimulated muscle 2-DG uptake (0.94 +/- 0.15 mumol.ml-1.20 min-1, controls; 0.46 +/- 0.06 mumol.ml-1.20 min-1, high-fat diet; 0.78 +/- 0.07 mumol.ml-1.20 min-1, high fat + DHEA). DHEA did not affect food intake. These results show that DHEA has a protective effect against accumulation of visceral fat and development of muscle insulin resistance in rats fed a high-fat diet.

Animals↗