Dehydroepiandrosterone (DHEA) is the most abundant steroid hormone in the circulation and has potent multifunctional activity. Epidemiological evidence suggests that levels of serum DHEA decrease with advancing age, and this has been associated with onset or progression of various age-related ailments, including cognitive decline and dementia, cardiovascular disease, and obesity. Consequently, these findings have sparked intense research interest in DHEA supplementation as an “antiaging” therapy. Currently, DHEA is being used by 25% of in vitro fertilization (IVF) clinicians as an adjuvant in assisted reproductive programs, yet the therapeutic benefit of DHEA is unclear. Here, we examined the use of novel DHEA-containing oral troches in patients undertaking IVF and investigated the impact of these troches on their serum androgen profile. This retrospective study determined the androgen profile of 31 IVF patients before (baseline) and after DHEA supplementation (with DHEA). Baseline serum measurements of testosterone (total and free), DHEA sulfate (DHEAS), sex hormone-binding globulin (SHBG), and androstenedione were made before and after supplementation. Each patient received DHEA troches containing 25 mg of micronized DHEA, and troches were administered sublingually twice daily for a period of no greater than 4 months. Adjuvant treatment with DHEA boosted the serum concentration of a number of androgen-related analytes, including total and free testosterone, androstenedione, and DHEAS, while serum SHBG remained unchanged. Supplementation also significantly increased the free-androgen index in IVF patients. Interestingly, the increase in serum analyte concentration following DHEA supplementation was found to be dependent on body mass index (BMI), but not individual age. Patients with the lowest BMI (<20.0 kg/m2) tended to have lower testosterone and DHEAS, but higher SHBG and androstenedione levels in comparison with other BMI groups postsupplementation. However, patients in the highest BMI group (>30.0 kg/m2) tended to have lower androgen responses following DHEA supplementation, but these were not statistically different from the corresponding baseline level. This method of DHEA administration results in a similar enhancement of testosterone, DHEAS, and androstenedione levels in comparison with other methods of administration. Furthermore, we showed that BMI significantly influences DHEA uptake and metabolism, and that BMI should be carefully considered during dosage calculation to ensure a significant and robust androgen-profile boost.
androstenedione; testosterone; sex hormone-binding globulin; IVF; oral troches; drug delivery
The biological basis of variability in histological progression of nonalcoholic fatty liver disease (NAFLD) is unknown. Dehydroepiandrosterone(DHEA) is the most abundant steroid hormone and has been shown to influence sensitivity to oxidative stress, insulin sensitivity, and expression of peroxisome proliferator-activated receptor alpha and procollagen messenger RNA. Our aim was to determine whether more histologically advanced NAFLD is associated with low circulating levels of DHEA. Serum samples were obtained prospectively at the time of liver biopsy in 439 patients with NAFLD (78 in an initial and 361 in validation cohorts) and in controls with cholestatic liver disease (n = 44). NAFLD was characterized as mild [simple steatosis or nonalcoholic steatohepatitis (NASH) with fibrosis stage 0–2] or advanced (NASH with fibrosis stage 3–4). Serum levels of sulfated DHEA (DHEA-S) were measured by enzyme-linked immunosorbent assay. Patients with advanced NAFLD had lower plasma levels of DHEA-S than patients with mild NAFLD in both the initial (0.25 ± 0.07 versus 1.1 ± 0.09 µg/mL, P < 0.001) and validation cohorts (0.47 ± 0.06 versus 0.99 ± 0.04 µg/mL, P < 0.001). A “dose effect” of decreasing DHEA-S and incremental fibrosis stage was observed with a mean DHEA-S of 1.03 ± 0.05, 0.96 ± 0.07, 0.83 ± 0.11, 0.66 ± 0.11, and 0.35 ± 0.06 µg/mL for fibrosis stages 0, 1, 2, 3, and 4, respectively. All patients in both cohorts in the advanced NAFLD group had low DHEA-S levels, with the majority in the hypoadrenal range. The association between DHEA-S and severity of NAFLD persisted after adjusting for age. A relationship between disease/fibrosis severity and DHEA-S levels was not seen in patients with cholestatic liver diseases.
More advanced NAFLD, as indicated by the presence of NASH with advanced fibrosis stage, is strongly associated with low circulating DHEA-S. These data provide novel evidence for relative DHEA-S deficiency in patients with histologically advanced NASH.
Glucocorticoids increase adipocyte proliferation and differentiation, a process underpinned by the local reactivation of inactive cortisone to active cortisol within adipocytes catalyzed by 11β-hydroxysteroid dehydrogenase type 1 (11β-HSD1). The adrenal sex steroid precursor dehydroepiandrosterone (DHEA) has been shown to inhibit 11β-HSD1 in murine adipocytes; however, rodent adrenals do not produce DHEA physiologically. Here, we aimed to determine the effects and underlying mechanisms of the potential antiglucocorticoid action of DHEA and its sulfate ester DHEAS in human preadipocytes. Utilizing a human subcutaneous preadipocyte cell line, Chub-S7, we examined the metabolism and effects of DHEA in human adipocytes, including adipocyte proliferation, differentiation, 11β-HSD1 expression, and activity and glucose uptake. DHEA, but not DHEAS, significantly inhibited preadipocyte proliferation via cell cycle arrest in the G1 phase independent of sex steroid and glucocorticoid receptor activation. 11β-HSD1 oxoreductase activity in differentiated adipocytes was inhibited by DHEA. DHEA coincubated with cortisone significantly inhibited preadipocyte differentiation, which was assessed by the expression of markers of early (LPL) and terminal (G3PDH) adipocyte differentiation. Coincubation with cortisol, negating the requirement for 11β-HSD1 oxoreductase activity, diminished the inhibitory effect of DHEA. Further consistent with glucocorticoid-opposing effects of DHEA, insulin-independent glucose uptake was significantly enhanced by DHEA treatment. DHEA increases basal glucose uptake and inhibits human preadipocyte proliferation and differentiation, thereby exerting an antiglucocorticoid action. DHEA inhibition of the amplification of glucocorticoid action mediated by 11β-HSD1 contributes to the inhibitory effect of DHEA on human preadipocyte differentiation.
dehydroepiandrosterone; human adipogenesis; 11β-hydroxysteroid dehydrogenase type 1; insulin sensitivity
The purpose of this study was to determine whether esterification of dehydroepiandrosterone with aspartate (DHEA-aspartate) could reduce peroxisomal proliferation induced by DHEA itself, without loss of antiosteoporotic activity. Female Sprague-Dawley rats were ovariectomized, then DHEA or DHEA-aspartate was administered intraperitoneally at 0.34 mmol/kg BW 3 times a week for 8 weeks. DHEA-aspartate treatment in ovariectomized rats significantly increased trabeculae area in tibia as much as DHEA treatment. Urinary Ca excretion was not significantly increased by DHEA or DHEA-aspartate treatment in ovariectomized rats, while it was significantly increased by ovariectomy. Osteocalcin concentration and alkaline phosphatase activity in serum and cross linked N-telopeptide type I collagen level in urine were not significantly different between DHEA-aspartate and DHEA treated groups. DHEA-aspartate treatment significantly reduced liver weight and hepatic palmitoyl-coA oxidase activity compared to DHEA treatment. DHEA-aspartate treatment maintained a nearly normal morphology of peroxisomes, while DHEA treatment increased the number and size of peroxisomes in the liver. According to these results, it is concluded that DHEA-aspartate ester has an inhibitory effect on bone loss in ovariectomized rats with a marked reduction of hepatomegaly and peroxisomal proliferation compared to DHEA.
Dehydroepiandrosterone (DHEA) is an endogenous steroid that blocks carcinogenesis, retards aging, and exerts antiproliferative properties. In vitro, it is a potent inhibitor of glucose-6-phosphate dehydrogenase, the first committed step of the pentose phosphate pathway. In man, serum levels of DHEA and its sulfate peak in early adulthood and drop markedly with age. Epidemiologic evidence indicates that low levels of DHEA or its sulfate conjugate are linked to an increased risk of developing cancer or of death from cardiovascular disease. Like cancer, atherosclerosis is a proliferative process characterized by both initiation and promotion phases. This similarity provided a framework in which to study the antiatherogenic effects of DHEA. Rabbits were randomly assigned to four groups. Two groups of rabbits received aortic endothelial injury by balloon catheter and were fed a 2% cholesterol diet for 12 wk. DHEA, 0.5%, was incorporated into the diet of one group receiving the 2% cholesterol diet and endothelial injury and also into the diet of one of the control groups. Animals were killed after 12 wk and aortas, hearts, and livers were studied. Plasma samples were analyzed for total cholesterol, VLDL, LDL, HDL, triglycerides, DHEA, and DHEA-sulfate levels. The atherogenic insult resulted in severe atherosclerosis in animals not treated with DHEA. In those receiving DHEA there was an almost 50% reduction in plaque size (P = 0.006), inversely related to the serum level of DHEA attained. Fatty infiltration of the heart and liver were also markedly reduced. These beneficial actions were not attributable to differences in body weight gain, food intake, total plasma cholesterol or distribution of cholesterol among the VLDL, LDL, or HDL fractions. The results show that high levels of plasma DHEA inhibit the development of atherosclerosis and they provide an important experimental link to the epidemiologic studies correlating low DHEA-sulfate plasma levels with an enhanced risk of cardiovascular mortality.
Dehydroepiandrosterone (DHEA) and its sulfate ester, Dehydroepiandrosterone Sulfate (DHEA-S) have been considered as putative anti-aging hormones for many years. Indeed, while DHEAS is the most abundant circulating hormone, its concentration is markedly decreased upon aging and early epidemiologic trials have revealed a strong inverse correlation between the hormone concentrations and the occurrence of several dysfunctions frequently encountered in the elderly. Naturally, hormonal supplementation has been rapidly suggested to prevent DHEA (S) deficiency and therefore, age-related development of these pathologies, using the same strategy as estrogen replacement therapy proposed in postmenopausal women.
All references were searched using PubMed and the following strategy: our initial selection included all articles in English and we sorted them with the following keywords: “DHEA or DHEA-S” and “heart or vascular or endothelium or cardiovascular disease”. The search was limited to neither the publication date nor specific journals. The final selection was made according to the relevance of the article content with the aims of the review. According to these criteria, fewer than 10% of the articles retrieved at the first step were discarded.
In this short review, we have focused on the cardiovascular action of DHEA. We started by analyzing evidences in favor of a strong inverse association between DHEA (S) levels and the cardiovascular risk as demonstrated in multiple observational epidemiologic studies for several decades. Then we discussed the different trials aimed at supplementing DHEA (S), both in animals and human, for preventing cardiovascular diseases and we analyzed the possible reasons for the discrepancy observed among the results of some studies. Finally, we presented putative molecular mechanisms of action for DHEA (S), demonstrated in vitro in different models of vascular and cardiac cells, highlighting the complexity of the involved signaling pathways.
The identification of the beneficial cardiovascular effects of DHEA (S) and a better understanding of the involved mechanisms should be helpful to develop new strategies or pharmacologic approaches for many lethal diseases in Western countries.
Dehydroepiandrosterone; Endothelium; Myocytes, Cardiac; Cardiovascular System; Disease; Steroids
Dehydroepiandrosterone (DHEA) is an abundant circulating prohormone in humans, with a variety of reported actions on central and peripheral tissues. Despite its abundance, the functions of DHEA are relatively unknown because common animal models (laboratory rats and mice) have very low DHEA levels in the blood. Over the past decade, we have obtained considerable evidence from avian studies demonstrating that (1) DHEA is an important circulating prohormone in songbirds and (2) the enzyme 3β-hydroxysteroid dehydrogenase/isomerase (3β-HSD), responsible for converting DHEA into a more active androgen, is expressed at high levels in the songbird brain. Here, we first review biochemical and molecular studies demonstrating the widespread activity and expression of 3β-HSD in the adult and developing songbird brain. Studies examining neural 3β-HSD activity show effects of sex, stress, and season that are region-specific. Second, we review studies showing seasonal and stress-related changes in circulating DHEA in captive and wild songbird species. Third, we describe evidence that DHEA treatment can stimulate song behavior and the growth of neural circuits controlling song behavior. Importantly, brain 3β-HSD and aromatase can work in concert to locally metabolize DHEA into active androgens and estrogens, which are critical for controlling behavior and robust adult neuroplasticity in songbirds. DHEA is likely secreted by the avian gonads and/or adrenals, as is the case in humans, but DHEA may also be synthesized de novo in the songbird brain from cholesterol or other precursors. Irrespective of its source, DHEA seems to be an important neurohormone in songbirds, and 3β-HSD is a key enzyme in the songbird brain.
3beta-HSD; adrenal; aggression; aromatase; brain; DHEA; estrogen; neurosteroid; season; song; sparrow; stress; testosterone; zebra finch
The adrenal steroid dehydroepiandrosterone (DHEA) and its sulfate (DHEAS) are two of the most abundant hormones in the human circulation. Furthermore, they are released in a circadian pattern and show a marked age-associated decline. Adult levels of DHEA and DHEAS are significantly higher in males than in females, but the reason for this sexual dimorphism is unclear. In the present study, we administered supplementary androgens [DHEA, testosterone and 5α-dihydrotestosterone (DHT)] to aged male rhesus macaques (Macaca mulatta). While this paradigm increased circulating DHEAS immediately after DHEA administration, an increase was also observed following either testosterone or DHT administration, resulting in hormonal profiles resembling levels observed in young males in terms of both amplitude and circadian pattern. This stimulatory effect was limited to DHEAS, as an increase in circulating cortisol was not observed. Taken together, these data demonstrate an influence of the hypothalamo-pituitary–testicular axis on adrenal function in males, possibly by sensitizing the zona reticularis to the stimulating action of adrenocorticopic hormone. This represents a plausible mechanism to explain sex differences in circulating DHEA and DHEAS levels, and may have important implications in the development of hormone therapies designed for elderly men and women.
adrenal gland; aging; androgen; dehydroepiandrosterone; non-human primate; testosterone
Dehydroepiandrosterone sulfate (DHEAS) is a circulating sulfated steroid considered to be a pro-androgen in mammalian physiology. Here we show that at a physiological concentration (1 μM), DHEAS induces the phosphorylation of the kinase Erk1/2 and of the transcription factors CREB and ATF-1 in the murine Sertoli cell line TM4. This signaling cascade stimulates the expression of the tight junction (TJ) proteins claudin-3 and claudin-5. As a consequence of the increased expression, tight junction connections between neighboring Sertoli cells are augmented, as demonstrated by measurements of transepithelial resistance. Phosphorylation of Erk1/2, CREB, or ATF-1 is not affected by the presence of the steroid sulfatase inhibitor STX64. Erk1/2 phosphorylation was not observed when dehydroepiandrosterone (DHEA) was used instead of DHEAS. Abrogation of androgen receptor (AR) expression by siRNA did not affect DHEAS-stimulated Erk1/2 phosphorylation, nor did it change DHEAS-induced stimulation of claudin-3 and claudin-5 expression. All of the above indicate that desulfation and conversion of DHEAS into a different steroid hormone is not required to trigger the DHEAS-induced signaling cascade. All activating effects of DHEAS, however, are abolished when the expression of the G-protein Gnα11 is suppressed by siRNA, including claudin-3 and -5 expression and TJ formation between neighboring Sertoli cells as indicated by reduced transepithelial resistance. Taken together, these results are consistent with the effects of DHEAS being mediated through a membrane-bound G-protein-coupled receptor interacting with Gnα11 in a signaling pathway that resembles the non-classical signaling pathways of steroid hormones. Considering the fact that DHEAS is produced in reproductive organs, these findings also suggest that DHEAS, by acting as an autonomous steroid hormone and influencing the formation and dynamics of the TJ at the blood-testis barrier, might play a crucial role for the regulation and maintenance of male fertility.
Steroid sulfatase (STS) cleaves the sulfate moiety off steroid sulfates, including dehydroepiandrosterone (DHEA) sulfate (DHEAS), the inactive sulfate ester of the adrenal androgen precursor DHEA. Deficient DHEA sulfation, the opposite enzymatic reaction to that catalyzed by STS, results in androgen excess by increased conversion of DHEA to active androgens. STS deficiency (STSD) due to deletions or inactivating mutations in the X-linked STS gene manifests with ichthyosis, but androgen synthesis and metabolism in STSD have not been studied in detail yet.
Patients and Methods:
We carried out a cross-sectional study in 30 males with STSD (age 6–27 y; 13 prepubertal, 5 peripubertal, and 12 postpubertal) and 38 age-, sex-, and Tanner stage-matched healthy controls. Serum and 24-hour urine steroid metabolome analysis was performed by mass spectrometry and genetic analysis of the STS gene by multiplex ligation-dependent probe amplification and Sanger sequencing.
Genetic analysis showed STS mutations in all patients, comprising 27 complete gene deletions, 1 intragenic deletion and 2 missense mutations. STSD patients had apparently normal pubertal development. Serum and 24-hour urinary DHEAS were increased in STSD, whereas serum DHEA and testosterone were decreased. However, total 24-hour urinary androgen excretion was similar to controls, with evidence of increased 5α-reductase activity in STSD. Prepubertal healthy controls showed a marked increase in the serum DHEA to DHEAS ratio that was absent in postpubertal controls and in STSD patients of any pubertal stage.
In STSD patients, an increased 5α-reductase activity appears to compensate for a reduced rate of androgen generation by enhancing peripheral androgen activation in affected patients. In healthy controls, we discovered a prepubertal surge in the serum DHEA to DHEAS ratio that was absent in STSD, indicative of physiologically up-regulated STS activity before puberty. This may represent a fine tuning mechanism for tissue-specific androgen activation preparing for the major changes in androgen production during puberty.
“Steroid metabolome analysis reveals mild androgen deficiency and compensatorily increased 5alpha-reductase activity in steroid sulfatase (STS) deficiency and upregulation of STS activity in healthy boys before puberty.”
Dehydroepiandrosterone sulfate (DHEAS) is the most abundant circulating steroid in human, with the highest concentrations between age 20 and 30, but displaying a significant decrease with age. Many beneficial functions are ascribed to DHEAS. Nevertheless, long-term studies are very scarce concerning the intake of DHEAS over several years, and molecular investigations on DHEAS action are missing so far. In this study, the role of DHEAS on the first and rate-limiting step of steroid hormone biosynthesis was analyzed in a reconstituted in vitro system, consisting of purified CYP11A1, adrenodoxin and adrenodoxin reductase. DHEAS enhances the conversion of cholesterol by 26%. Detailed analyses of the mechanism of DHEAS action revealed increased binding affinity of cholesterol to CYP11A1 and enforced interaction with the electron transfer partner, adrenodoxin. Difference spectroscopy showed Kd-values of 40±2.7 µM and 24.8±0.5 µM for CYP11A1 and cholesterol without and with addition of DHEAS, respectively. To determine the Kd-value for CYP11A1 and adrenodoxin, surface plasmon resonance measurements were performed, demonstrating a Kd-value of 3.0±0.35 nM (with cholesterol) and of 2.4±0.05 nM when cholesterol and DHEAS were added. Kinetic experiments showed a lower Km and a higher kcat value for CYP11A1 in the presence of DHEAS leading to an increase of the catalytic efficiency by 75%. These findings indicate that DHEAS affects steroid hormone biosynthesis on a molecular level resulting in an increased formation of pregnenolone.
Aging is associated with diminished gonadal steroid and GH/IGF-I axis activity; whether these changes contribute to the parallel declines of dehydroepiandrosterone (DHEA) and DHEA sulfate (DHEAS) production is unknown, as are the effects of sex steroid and/or GH administration on DHEA and DHEAS production.
Our objective was to evaluate morning DHEAS concentrations and nocturnal DHEA secretory dynamics in healthy older men and women, before and after chronic administration of sex steroid(s) alone, GH alone, sex steroid(s) combined with GH, or placebo alone.
We compared nocturnal DHEA secretory dynamics (2000 h to 0800 h, sampling every 20 min, analyzed by multiparameter deconvolution and approximate entropy algorithms) in healthy older (65–88 yr) men (n = 68) and women (n = 36), both before and after 26 wk of administration of sex steroid(s) alone [testosterone (T) in men or estrogen/progesterone in women], GH alone, sex steroid(s) combined with GH, or placebo alone.
Morning concentrations of DHEAS were lower; nocturnal DHEA pulsatile production rate, burst frequency, and amplitude were higher; and half-life was shorter in women (P < 0.05). Nocturnal integrated DHEA concentrations, total production rate, and approximate entropy did not differ significantly by sex. Because of small treatment group sizes in women, only hormone intervention results in men are presented. In men, T and T plus GH administration significantly decreased nocturnal integrated DHEA but not morning DHEAS concentrations. GH alone exerted no significant effects on nocturnal DHEA secretion or morning DHEAS.
Spontaneous nocturnal DHEA secretion is sexually dimorphic in healthy older individuals, and T administration decreases nocturnal DHEA secretion in older men. The clinical significance of sex steroid modulation of DHEA secretion in older persons remains to be elucidated.
Dehydroepiandrosterone (DHEA) is important for human health, especially for women. All estrogens and practically half of androgens are synthesized from DHEA in peripheral tissues. However, the mechanism and exact target tissues of DHEA biotransformation in the female are not fully clear. The present study showed that maximal content of androstenedione (AD) and testosterone (T) were observed at 3h after DHEA administration in female rats, which was 264% and 8000% above the control, respectively. Estradiol (E2) content significantly increased at 6h after DHEA administration, which was 113% higher than that in control group. Gavage with DHEA could significantly reduce 3β-hydroxysteroid dehydrogenase (3β-HSD) mRNA level at 3-12h and 17β-hydroxysteroid dehydrogenase (17β-HSD) mRNA level at 12h in ovary, while increasing aromatase mRNA levels at 6, 24, and 48h. It is interesting that administration of DHEA caused a significant increase of 17β-HSD, 3β-HSD and aromatase mRNA levels in adrenal. The AD and T contents also markedly increased by 537% and 2737% after DHEA administration in ovariectomised rats, in company with a significant increase in 17β-HSD and 3β-HSD mRNA levels and decreased aromatase mRNA level in adrenal. However, DHEA administration did not restore the decreased E2, estrone (E1), and progesterone (P) caused by the removal of the ovaries in females. These results clearly illustrated that exogenous DHEA is preferentially converted into androgens in adrenal, while its conversion to estrogens mainly happens in the ovary through steroidogenic enzyme in female rats.
Dehydroepiandrosterone (DHEA), a 19-carbon precursor of sex steroids, is abundantly produced in the human but not the mouse adrenal. However, mice produce DHEA and DHEA-sulfate (DHEAS) in the fetal brain. DHEA stimulates axonal growth from specific populations of mouse neocortical neurons in vitro, while DHEAS stimulates dendritic growth from those cells. The synthesis of DHEA and sex steroids, but not mouse glucocorticoids and mineralocorticoids, requires P450c17, which catalyzes both 17α-hydroxylase and 17,20-lyase activities. We hypothesized that P450c17-knockout mice would have disordered sex steroid synthesis and disordered brain DHEA production and thus provide phenotypic clues about the functions of DHEA in mouse brain development. We deleted the mouse P450c17 gene in 127/SvJ mice and obtained several lines of mice from two lines of targeted embryonic stem cells. Heterozygotes were phenotypically and reproductively normal, but in all mouse lines, P450c17−/− zygotes died by embryonic day 7, prior to gastrulation. The cause of this early lethality is unknown, as there is no known function of fetal steroids at embryonic day 7. Immunocytochemistry identified P450c17 in embryonic endoderm in E7 wild-type and heterozygous embryos, but its function in these cells is unknown. Enzyme assays of wild-type embryos showed a rapid rise in 17-hydroxylase activity between E6 and E7 and the presence of C17,20-lyase activity at E7. Treatment of pregnant females with subcutaneous pellets releasing DHEA or 17-OH pregnenolone at a constant rate failed to rescue P450c17−/− fetuses. Treatment of normal pregnant females with pellets releasing pregnenolone or progesterone did not cause fetal demise. These data suggest that steroid products of P450c17 have heretofore-unknown essential functions in early embryonic mouse development.
Stress has well-known effects on adrenal glucocorticoid secretion, and chronic elevation of glucocorticoids can have detrimental effects on the brain. Dehydroepiandrosterone (DHEA), an androgen precursor synthesized in the adrenal glands or the brain itself, has anti-glucocorticoid properties, but little is known about the role of DHEA in the stress response, particularly in the brain. Here, we measured the effects of acute restraint on circulating corticosterone (CORT) and DHEA levels in wild song sparrows. Blood was collected from either the brachial or jugular vein. In songbirds, jugular plasma is enriched with neurally synthesized steroids, and therefore, jugular plasma is an indirect index of the neural steroidal milieu. Subjects were sampled during four times of year: breeding, molt, early nonbreeding, and mid-nonbreeding. Baseline CORT and DHEA levels showed similar seasonal changes; both steroids were elevated during the breeding season. Baseline CORT and DHEA levels were similar in jugular and brachial plasma. Acute stress had robust effects on CORT and DHEA that were season specific and vein specific. For CORT, during the molt, stress increased jugular CORT more than brachial CORT. For DHEA, during the breeding season, stress decreased jugular DHEA but not brachial DHEA. During the molt, stress increased jugular DHEA but not brachial DHEA. Acute stress did not affect brachial DHEA. These data suggest that acute stress specifically affects the balance between DHEA synthesis and metabolism in the brain. Furthermore, these results suggest that CORT and DHEA are locally synthesized in the brain during molt, when systemic levels of CORT and DHEA are low.
PMID: 18276756 CAMSID: cams343
The neurosteroid dehydroepiandrosterone (DHEA), produced by neurons and glia, affects multiple processes in the brain, including neuronal survival and neurogenesis during development and in aging. We provide evidence that DHEA interacts with pro-survival TrkA and pro-death p75NTR membrane receptors of neurotrophin nerve growth factor (NGF), acting as a neurotrophic factor: (1) the anti-apoptotic effects of DHEA were reversed by siRNA against TrkA or by a specific TrkA inhibitor; (2) [3H]-DHEA binding assays showed that it bound to membranes isolated from HEK293 cells transfected with the cDNAs of TrkA and p75NTR receptors (KD: 7.4±1.75 nM and 5.6±0.55 nM, respectively); (3) immobilized DHEA pulled down recombinant and naturally expressed TrkA and p75NTR receptors; (4) DHEA induced TrkA phosphorylation and NGF receptor-mediated signaling; Shc, Akt, and ERK1/2 kinases down-stream to TrkA receptors and TRAF6, RIP2, and RhoGDI interactors of p75NTR receptors; and (5) DHEA rescued from apoptosis TrkA receptor positive sensory neurons of dorsal root ganglia in NGF null embryos and compensated NGF in rescuing from apoptosis NGF receptor positive sympathetic neurons of embryonic superior cervical ganglia. Phylogenetic findings on the evolution of neurotrophins, their receptors, and CYP17, the enzyme responsible for DHEA biosynthesis, combined with our data support the hypothesis that DHEA served as a phylogenetically ancient neurotrophic factor.
Dehydroepiandrosterone (DHEA) and its sulphate ester are the most abundant steroid hormones in humans, and DHEA was described as the first neurosteroid produced in the brain. DHEA is known to participate in multiple events in the brain, including neuronal survival and neurogenesis. However, to date no specific cellular receptor has been described for this important neurosteroid. In this study, we provide evidence that DHEA exerts its neurotrophic effects by directly interacting with the TrkA and p75NTR membrane receptors of nerve growth factor (NGF), and efficiently activates their downstream signaling pathways. This activation prevents the apoptotic loss of NGF receptor positive sensory and sympathetic neurons. The interaction of DHEA with NGF receptors may also offer a mechanistic explanation for the multiple actions of DHEA in other peripheral biological systems expressing NGF receptors, such as the immune, reproductive, and cardiovascular systems.
Prolonged increases in plasma glucocorticoids can exacerbate neurodegeneration. In rats, these neurodegenerative effects can be reduced by dehydroepiandrosterone (DHEA), an androgen precursor with anti-glucocorticoid actions. In song sparrows, season and acute restraint stress affect circulating levels of corticosterone and DHEA, and the effects of stress differ in plasma collected from the brachial and jugular veins. Jugular plasma is an indirect index of the neural steroidal milieu. Here, we directly measured corticosterone and DHEA in several brain regions and jugular plasma, and examined the effects of season and acute restraint stress (30 min) (n = 571 samples). Corticosterone levels were up to 10× lower in brain than in jugular plasma. In contrast, DHEA levels were up to 5× higher in brain than in jugular plasma and were highest in the hippocampus. Corticosterone and DHEA concentrations were strongly seasonally regulated in plasma but, surprisingly, not seasonally regulated in brain. Acute stress increased corticosterone levels in plasma and brain, except during the molt, when stress unexpectedly decreased corticosterone levels in the hippocampus. Acute stress increased DHEA levels in plasma during the molt but had no effects on DHEA levels in brain. This is the first study to measure (i) corticosterone or DHEA levels in the brain of adult songbirds and (ii) seasonal changes in corticosterone or DHEA levels in the brain of any species. These results highlight several critical differences between systemic and local steroid concentrations and the difficulty of using circulating steroid levels to infer local steroid levels within the brain.
PMID: 19473242 CAMSID: cams333
DHEA; glucocorticoid; hippocampus; molt; neurosteroid; song sparrow
Neurosteroid dehydroepiandrosterone sulfate (DHEAS) has been associated with important brain functions, including neuronal survival, memory, and behavior, showing therapeutic potential in various neuropsychiatric and cognitive disorders. However, the antagonistic effects of DHEAS on γ-amino-butyric acidA receptors and its facilitatory action on glutamatergic neurotransmission might lead to enhanced brain excitability and seizures and thus limit DHEAS therapeutic applications. The aim of this study was to investigate possible age and sex differences in the neuronal excitability of the mice following acute and chronic DHEAS administration.
DHEAS was administered intraperitoneally in male and female adult and old mice either acutely or repeatedly once daily for 4 weeks in a 10 mg/kg dose. To investigate the potential proconvulsant properties of DHEAS, we studied the effects of acute and chronic DHEAS treatment on picrotoxin-, pentylentetrazole-, and N-methyl-D-aspartate-induced seizures in mice. The effects of acute and chronic DHEAS administration on the locomotor activity, motor coordination, and body weight of the mice were also studied. We also investigated the effects of DHEAS treatment on [3H]flunitrazepam binding to the mouse brain membranes.
DHEAS did not modify the locomotor activity, motor coordination, body weight, and brain [3H]flunitrazepam binding of male and female mice. The results failed to demonstrate significant effects of single- and long-term DHEAS treatment on the convulsive susceptibility in both adult and aged mice of both sexes. However, small but significant changes regarding sex differences in the susceptibility to seizures were observed following DHEAS administration to mice.
Although our findings suggest that DHEAS treatment might be safe for various potential therapeutic applications in adult as well as in old age, they also support subtle interaction of DHEAS with male and female hormonal status, which may underline observed sex differences in the relationship between DHEAS and various health outcomes.
dehydroepiandrosterone sulfate; mice; age and sex differences; seizure threshold; motor activity; [3H]flunitrazepam binding
The effects of multiple-dosing with dehydroepiandrosterone sulfate (DHEA-SO4) on the pharmacokinetics and pharmacodynamics of prednisolone were examined. Prednisolone (25 mg/kg i.v.) was administered to male and female Sprague-Dawley rats (250–350 g) alone and following DHEA-SO4 (4 mg/kg i.v., every 8 h for 4 days). Male control rats cleared prednisolone faster [3.68 ± 1.30 (males) vs 1.01 ± 0.7 1/h/kg; p<0.05] and had larger Vss (1.38 ± 0.459 vs 0.394 ± 0.500 1/kg; p<0.05) than females both due largely to lesser plasma protein binding. Prednisolone clearance and Vss were not altered by DHEA-SO4 in males or females. The net effect of prednisolone on basophils and plasma corticosterone did not differ with gender. DHEA-SO4 had no effect on plasma corticosterone and did not alter prednisolone action. DHEA-SO4 inhibited basophil trafficking in males, but to a lesser extent than prednisolone, and antagonized the effect of prednisolone on basophil trafficking in both sexes. The steroid-sparing effect observed with DHEA clinically may not be due to an alteration of corticosteroid pharmacokinetics but partly to its ability to affect immune functions.
prednisolone; dehydroepiandrosterone; pharmacokinetics; pharmacodynamics; basophil trafficking; corticosterone suppression
It is generally assumed that steroid hormones are carried in the blood free and/or bound to plasma proteins. We investigated whether blood cells were also able to bind/carry sex-related hormones: estrone, estradiol, DHEA and testosterone. Wistar male and female rats were fed a cafeteria diet for 30 days, which induced overweight. The rats were fed the standard rat diet for 15 additional days to minimize the immediate effects of excess ingested energy. Controls were always kept on standard diet. After the rats were killed, their blood was used for 1) measuring plasma hormone levels, 2) determining the binding of labeled hormones to washed red blood cells (RBC), 3) incubating whole blood with labeled hormones and determining the distribution of label between plasma and packed cells, discounting the trapped plasma volume, 4) determining free plasma hormone using labeled hormones, both through membrane ultrafiltration and dextran-charcoal removal. The results were computed individually for each rat. Cells retained up to 32% estrone, and down to 10% of testosterone, with marked differences due to sex and diet (the latter only for estrogens, not for DHEA and testosterone). Sex and diet also affected the concentrations of all hormones, with no significant diet effects for estradiol and DHEA, but with considerable interaction between both factors. Binding to RBC was non-specific for all hormones. Estrogen distribution in plasma compartments was affected by sex and diet. In conclusion: a) there is a large non-specific RBC-carried compartment for estrone, estradiol, DHEA and testosterone deeply affected by sex; b) Prior exposure to a cafeteria (hyperlipidic) diet induced hormone distribution changes, affected by sex, which hint at sex-related structural differences in RBC membranes; c) We postulate that the RBC compartment may contribute to maintain free (i.e., fully active) sex hormone levels in a way similar to plasma proteins non-specific binding.
We propose that the adrenal gland of an older higher primate female animal model will respond to a human chorionic gonadotropic (hCG) hormone challenge by secreting additional dehydroepiandrosterone sulfate (DHEAS). Such a response in surgically and chemically-castrated animals will provide proof-of-concept and a validated animal model for future studies to explore the rise of DHEAS during the menopausal transition of women.
Twenty four 18–26 y/o female cynomolgus monkeys were screened for ovarian function then either ovariectomized (n=4) or treated with a gonadotropic releasing hormone agonist (GnRHa) (n=20) to block ovarian steroid production. Following a recovery period from surgery or down-regulation, a single dose challenge (1,000 IU; IM) of human chorionic gonadotropin (hCG) was then administered in order to determine if LH/CG could accelerate circulating DHEAS production. Serum DHEAS, bioactive LH and urinary metabolites of ovarian sex steroids were monitored before, during and following these treatments.
Circulating LH bioactivity and immunoreactive DHEAS concentrations were suppressed in all animals 14 days post administration of GnRHa. Urinary metabolites of estradiol and progesterone remained low following surgery or the flare reaction to GnRHa. Circulating DHEAS levels were increased following hCG administration and the increase in individual animals was proportional to the pre-treatment DHEAS baseline. Circulating DHEAS concentrations were positively correlated to endogenous LH bioactive concentrations prior to, and were increased by hCG challenge while no concomitant change was observed in ovarian steroid hormone excretion.
These data demonstrate a positive adrenal androgen response to LH/CG in older female higher primates and suggests a mechanism for the rise in adrenal androgen production during the menopausal transition in women. These results also illustrate that the nonhuman primate animal model can be effectively used to investigate this phenomenon.
DHEAS; menopause; adrenal androgens; LH/hCG
Trichloroethylene (TCE) and related hydrocarbons constitute an important class of environmental pollutants whose adverse effects on liver, kidney, and other tissues may, in part, be mediated by peroxisome proliferator-activated receptors (PPARs), ligand-activated transcription factors belonging to the steroid receptor superfamily. Activation of PPAR induces a dramatic proliferation of peroxisomes in rodent hepatocytes and ultimately leads to hepatocellular carcinoma. To elucidate the role of PPAR in the pathophysiologic effects of TCE and its metabolites, it is important to understand the mechanisms whereby PPAR is activated both by TCE and endogenous peroxisome proliferators. The investigations summarized in this article a) help clarify the mechanism by which TCE and its metabolites induce peroxisome proliferation and b) explore the potential role of the adrenal steroid and anticarcinogen dehydroepiandrosterone 3beta-sulfate (DHEA-S) as an endogenous PPAR activator. Transient transfection studies have demonstrated that the TCE metabolites trichloroacetate and dichloroacetate both activate PPAR alpha, a major liver-expressed receptor isoform. TCE itself was inactive when tested over the same concentration range, suggesting that its acidic metabolites mediate the peroxisome proliferative potential of TCE. Although DHEA-S is an active peroxisome proliferator in vivo, this steroid does not stimulate trans-activation of PPAR alpha or of two other PPAR isoforms, gamma and delta/Nuc1, when evaluated in COS-1 cell transfection studies. To test whether PPAR alpha mediates peroxisomal gene induction by DHEA-S in intact animals, DHEA-S has been administered to mice lacking a functional PPAR alpha gene. DHEA-S was thus shown to markedly increase hepatic expression of two microsomal P4504A proteins associated with the peroxisomal proliferative response in wild-type mice. In contrast, DHEA-S did not induce these hepatic proteins in PPAR alpha-deficient mice. Thus, despite its unresponsiveness to steroidal peroxisome proliferators in transfection assays, PPAR alpha is an obligatory mediator of DHEA-S-stimulated hepatic peroxisomal gene induction. DHEA-S, or one of its metabolites, may thus serve as an important endogenous regulator of liver peroxisomal enzyme expression.
Dehydroepiandrosterone (DHEA), a C19 human adrenal steroid, activates peroxisome proliferator-activated receptor α (PPARα) in vivo but does not ligand-activate PPARα in transient transfection experiments. We demonstrate that DHEA regulates PPARα action by altering both the levels and phosphorylation status of the receptor. Human hepatoma cells (HepG2) were transiently transfected with the expression plasmid encoding PPARα and a plasmid containing two copies of fatty acyl coenzyme oxidase (FACO) peroxisome-proliferator activated receptor responsive element consensus oligonucleotide in a luciferase reporter gene. Nafenopin treatment increased reporter gene activity in this system, whereas DHEA treatment did not. Okadaic acid significantly decreased nafenopin-induced reporter activity in a concentration-dependent manner. Okadaic acid treatment of primary rat hepatocytes decreased both DHEA- and nafenopin-induced FACO activity in primary rat hepatocytes. DHEA induced both PPARα mRNA and protein levels, as well as PP2A message in primary rat hepatocytes. Western blot analysis showed that the serines at positions 12 and 21 were rapidly dephosphorylated upon treatment with DHEA and nafenopin. Results using specific protein phosphatase inhibitors suggested that protein phosphatase 2A (PP2A) is responsible for DHEA action, and protein phosphatase 1 might be involved in nafenopin induction. Mutation of serines at position 6, 12, and 21 to an uncharged alanine residue significantly increased transcriptional activity, whereas mutation to negative charged aspartate residues (mimicking receptor phosphorylation) decreased transcriptional activity. DHEA action involves induction of PPARα mRNA and protein levels as well as increased PPARα transcriptional activity through decreasing receptor phosphorylation at serines in the AF1 region.
The steroid hormone dehydroepiandrosterone (DHEA) exerts protecting effects in the treatment of traumatic and septic complications in several animal models. This effect goes along with reduced amounts of infiltrating immune cells in organs such as lung and liver. However, the underlying mechanisms of DHEA action are still not known. Adhesion molecules are important for the extravasation of neutrophils into organs where they may exhibit detrimental effects. Therefore, we investigated the in vitro effect of DHEA on the expression pattern of adhesion molecules of human endothelial cells and neutrophils.
Endothelial cells derived from human umbilical cord were subjected to an lipopolysaccharide (LPS) challenge. DHEA was administered in two different concentrations, 10-5 M and 10-8 M, as a single stimulus or in combination with LPS challenge. After two, four and 24 hours, fluorescence activated cell sorter (FACS) analysis for vascular cell adhesion molecule-1, intercellular adhesion molecule-1 and E-selectin was performed. Neutrophils were freshly isolated from blood of 10 male healthy volunteers, stimulated the same way as endothelial cells and analyzed for surface expression of L-selectin, CD11b and CD18.
In the present study, we were able to demonstrate effects of DHEA on the expression of every adhesion molecule investigated. DHEA exhibits opposite effects to those seen upon LPS exposure. Furthermore, these effects are both time and concentration dependent as most DHEA specific effects could be detected in the physiological concentration of 10-8 M.
Thus, we conclude that one mechanism by which DHEA may exert its protection in animal models is via the differential regulation of adhesion molecule expression.
Men show an age-related decline in the circulating levels of testosterone (T) and dehydroepiandrosterone sulfate (DHEAS). Consequently, there is interest in developing androgen supplementation paradigms for old men that replicate the hormone profiles of young adults. In the present study, we used old (21–26 years old) male rhesus monkeys as a model to examine the efficacy of an androgen supplementation paradigm that comprised oral T administration (12 mg/kg body weight, dissolved in sesame oil/chocolate) in the evening, and two oral DHEA administrations, 3 hr apart (0.04 mg/kg body weight, dissolved in sesame oil/chocolate) in the morning. After 5 days of repeated hormone supplementation, serial blood samples were remotely collected from each animal hourly across the 24-hr day, and assayed for cortisol, DHEAS, T, 5α-dihydrotestosterone (DHT), estrone (E1), and 17β-estradiol (E2). Following androgen supplementation, T levels were significantly elevated and this was associated with a more sustained nocturnal elevation of T's primary bioactive metabolites, DHT and E1 and E2. Plasma DHEAS levels were also significantly elevated after androgen supplementation; DHEAS levels rose in the early morning and gradually declined during the course of the day, closely mimicking the profiles observed in young adults (7–12 years old); in contrast, cortisol levels were unaltered by the supplementation. Together the data demonstrate a non-invasive androgen supplementation paradigm that restores youthful circulating androgen levels in old male primates. Because this paradigm preserves the natural circulating circadian hormone patterns, we predict that it will produce fewer adverse side effects, such as perturbed sleep or cognitive impairment.