Plasma levels of epitestosterone from prepuberty to adult life

5α-reduction of epitestosterone is catalysed by human SRD5A1 and SRD5A2 and increases androgen receptor transactivation

Epitestosterone is a stereoisomer of the active androgen testosterone and its circulating concentrations are similar to those of testosterone in women and children. However, its biological function and pathways of metabolism remain unknown. The structural similarity to testosterone suggests a potential function in the modulation of androgen receptor signalling. It is well established that the conversion of testosterone to 5α-dihydrotestosterone enhances local androgen receptor signalling. In this study, we show that epitestosterone is metabolized to 5α-dihydroepitestosterone by both human steroid 5α-reductase isoforms, SRD5A1 and SRD5A2. Using two different variations of a reporter assay for transactivation of the human androgen receptor, we show that epitestosterone is a partial AR agonist and that the 5α-reduction of epitestosterone increases its androgenic activity. In line with this, we show that 5α-reduction of epitestosterone reduces its ability to antagonize 5α-dihydrotestosterone-induced androgen receptor transactivation. In conclusion, we provide evidence that steroid 5α-reductases regulate the modulatory effect of epitestosterone on androgen receptor signalling.

Copy number variations in autistic children

Autism spectrum disorder (ASD) manifests as a neurodevelopmental condition marked by challenges in social communication, interaction and the performing of repetitive behaviors. The prevalence of autism increases markedly on an annual basis; however, the etiology remains incompletely understood. Cytogenetically visible chromosomal abnormalities, including copy number variations (CNVs), have been shown to contribute to the pathogenesis of ASD. More than 1% of ASD conditions can be explained based on a known genetic locus, whereas CNVs account for 5-10% of cases. However, there are no studies on the Saudi Arabian population for the detection of CNVs linked to ASD, to the best of our knowledge. Therefore, the aim of the present study was to explore the prevalence of CNVs in autistic Saudi Arabian children. Genomic DNA was extracted from the peripheral blood of 14 autistic children along with four healthy control children and then array-based comparative genomic hybridization (aCGH) was used to detect CNVs. Bioinformatics analysis of the aCGH results showed the presence of recurrent and non-recurrent deletion/duplication CNVs in several regions of the genome of autistic children. The most frequent CNVs were 1q21.2, 3p26.3, 4q13.2, 6p25.3, 6q24.2, 7p21.1, 7q34, 7q11.1, 8p23.2, 13q32.3, 14q11.1-q11.2 and 15q11.1-q11.2. In the present study, CNVs in autistic Saudi Arabian children were identified to improve the understanding of the etiology of autism and facilitate its diagnosis. Additionally, the present study identified certain possible pathogenic genes in the CNV region associated with several developmental and neurogenetic diseases.

Testosterone/Epitestosterone Ratios-Further Hints to Explain Hyperandrogenemia in Children with Autism

BACKGROUND

Epitestosterone [E] has for a long time been considered as a biologically inactive androgen. However, recently a distinct antiandrogenic activity of this naturally occurring endogenous epimer of Testosterone has been demonstrated. Especially the ratios of testosterone/epitestosterone (T/E) seem to be key as inhibition of epitestosterone on androgen activity was postulated. As in autism, a higher androgen activity was implied. We, therefore, suggested higher levels of T/E ratios of children with autism versus children with typical development.

METHODS

Urine probes of 22 girls with autism (BMI 18.7 ± 4.3; average age 12.3 ± 3.8 years) and a sample of 51 controls (BMI 17.0 ± 2.6; average age 11.9 ± 4 years), as well as 61 boys with autism (BMI 17.04 ± 2. average age 11.9 ± 2.5 years) and 61 control boys (BMI 17.0 ± 2.6; average age 11.1 ± 3.0 years), were analyzed with gas chromatography mass spectrometry.

RESULTS

The average T/E ratio of all boys with autism was 2.5 ± 1.8 versus 2.4 ± 1.3 in boys with typical development, respectively. No significant difference between boys with autism versus boys with typical development could be detected (p = 0.977). In girls with autism, the average T/E ratio was 1.4 ± 0.9 versus 2.0 ± 1.4 in girls with typical development, whereby a significant difference could be detected (p = 0.0285). Further, polynomial analysis of the third degree were conducted, showing a dependence from age with reasonable coefficients of determination (0.075 < R² < 0.22, all samples).

DISCUSSION

As encompassing steroid hormone analysis are expensive and work-intensive, we hoped to find an easily applicable biomarker to support diagnostics in autism. However, as a relatively small sample of only 22 girls with autism were analyzed and menstrual cycle and pubertal status were only partly controllable through the matching of BMI and age, the question arises if it was an incidental finding. Nevertheless, one suggestion might be that epitestosterone has the effect of a competitive inhibition on the androgen receptor, which would probably help to explain the higher prevalence of autism in boys as compared to girls. Presumably, as no significant difference was detected in boys, this effect might not be as relevant from a steroid hormone perspective, and other effects such as altered 17/20-hydroxylase activity as previously shown in boys and girls with autism seem to have more relevance. Analysis of larger samples, including plenty of metabolites and enzymatic cascades, as well as the role of backdoor pathway activity of androgen synthesis of girls with autism, are demanded in order to validate current findings of altered steroid hormones in autism.

Epitestosterone- and testosterone-replacement in immature castrated rats changes main testicular developmental characteristics

Epitestosterone is the 17α-epimer of testosterone and has been described as an anti-androgen, since it inhibits the effects produced by testosterone and dihydrotestosterone via the nuclear androgen receptor (nAR). However, epitestosterone also displays an effect which is similar to the non-classical effect of testosterone, depolarizing the membrane potential of Sertoli cells and inducing a rapid Ca²⁺ uptake. This study aimed to investigate the effects of a treatment with epitestosterone on developmental parameters of immature rats. Animals were chemically castrated by using the gonadotropin-releasing hormone (GnRH) antagonist cetrorelix and then received a replacement of 7 days with epitestosterone or testosterone. Replacement with either epitestosterone or testosterone restored the anogenital distance (AGD) and testicular weight which had been reduced by chemical castration. The immunocontent of nAR and the nAR-immunoreactivity were reduced by epitestosterone treatment in the testis of both castrated and non-castrated animals. Furthermore, testosterone was unable of changing the membrane potential of Sertoli cells through its non-classical action in the group of animals castrated and replaced with epitestosterone. In conclusion, in relation to the level of protein expression of nAR epitestosterone acts as an anti-androgen. However, it acts in the same way as testosterone when genital development parameters are evaluated. Moreover, in castrated rats epitestosterone suppressed the non-classical response of testosterone, changing the pattern of testosterone signalling via a membrane mechanism in Sertoli cells.

Flowers for Algernon: steroid dysgenesis, epigenetics and brain disorders

While a recent study has reported that early citalopram exposure alters cortical network function and produces autistic-like behaviors in male rats, when evaluating antidepressant animal models of autism spectrum disorder (ASD) it is important to note that some selective serotonin (5-HT) reuptake inhibitors alter 3α-hydroxysteroid dehydrogenase activity, and thus steroidogenesis. At least one study has examined the effect of repeated citalopram administration on the serum and brain concentration of testosterone (T) and its metabolites and shown that citalopram increases serum T. Several in vitro studies also suggest that sex steroid can alter 5-HT homeostasis. While research efforts have demonstrated that transgenic mice expressing the most common of multiple gain-of-function 5-HT reuptake transporter (SERT) coding variants, SERT Ala56, previously identified in children with ASD, exhibit autistic-like behaviors, elevated p38 MAPK-dependent transporter phosphorylation, enhanced 5-HT clearance rates and hyperserotonemia, a few studies provide some evidence that 5-HT may alter gonadal steroidogenesis. T, 17β-estradiol and synthetic estrogens are known inhibitors of AKR1C21 (BRENDA, E.C. 1.1.1.209), the epitestosterone (epiT) producing enzyme in rodents. EpiT is a naturally occurring steroid in mammals, including man. An analysis of the literature suggests that epiT may be the central mediator in the epigenetic regulation of gene expression. Over thirty years ago, it was shown that rat brain epiT production is higher in females than in males. A similar finding in humans could explain the sex differences in the incidence of autism and other brain disorders. Despite this, the role of epiT in brain development remains a long neglected area of research.

LC-MS analysis of androgen metabolites in serum and urine from east African chimpanzees (Pan troglodytes schweinfurthii)

Testosterone regulates a wide variety of behavioral and physiological traits in male vertebrates. It influences reproductive and aggressive behaviors and is used as a marker of gonadal activity. While testosterone is the primary biologically active male gonadal steroid in the blood, it is metabolized into a variety of related steroids when excreted via urine and feces. To monitor endocrinological profiles studies on wild-living animals primarily rely on non-invasively collected samples such as urine or feces. Since a number of androgen metabolites that are found in high concentrations in these matrices do not stem exclusively from gonadal production, but are also produced by the adrenal cortex, the metabolism and excretion pattern of testosterone and its characteristic metabolites have to be investigated. Here, we compare the levels of 11 androgens and their metabolites in serum and urine (after hydrolytic/solvolytic cleavage of conjugates) from female, and intact and castrated male chimpanzees to investigate whether they were of testicular or adrenal origin. For serum, significant differences in concentrations were found only for native testosterone. For urine, testosterone concentrations showed the largest differences between intact and castrated males, and intact males and females, while no differences were seen between females and castrated males. Epitestosterone levels revealed the same pattern. These differences in urinary concentrations could also be seen for 5α-androstane-3α,17β-diol (androstanediol), and less clearly for 5α-dihydrotestosterone (5α-DHT), etiocholanolone, and androsterone. In urine of males, significant correlations were found between the levels of testosterone and 5α-androstane-3α,17β-diol, as well as between testosterone and epitestosterone. Therefore, the clearest urinary markers of gonadal activity in male chimpanzees seems to be testosterone itself.

Biochemical and physiological aspects of endogenous androgens

This review attempts to give a synopsis of the major aspects concerning the biochemistry of endogenous androgens, supplemented with several facets of physiology, particularly with respect to testosterone. Testosterone continues to be the most common adverse finding declared by World Anti-Doping Agency accredited laboratories, such samples having an augmented testosterone to epitestosterone ratio. Knowledge regarding the precursors and metabolism of endogenous testosterone is therefore fundamental to understanding many of the issues concerning doping with testosterone and its prohormones, including the detection of their administration. Further, adverse findings for nandrolone are frequent, but this steroid and 19-norandrostenedione are also produced endogenously, an appealing hypothesis being that they are minor by-products of the aromatization of androgens. At sports tribunals pertaining to adverse analytical findings of natural androgen administration, experts often raise issues that concern some aspect of steroid biochemistry and physiology. Salient topics included within this review are the origins and interconversion of endogenous androgens, the biosynthesis of testosterone and epitestosterone, the mechanism of aromatization, the molecular biology of the androgen receptor, the hypothalamic-pituitary-testicular axis, disturbances to this axis by anabolic steroid administration, the transport (binding) of androgens in blood, and briefly the metabolism and excretion of androgens.

Sex, drugs and sports: Prostaglandins, epitestosterone and sexual development

Amateau and McCarthy's findings published in Nature Neuroscience (June 2004) are noteworthy for suggesting a role for prostaglandins in sexual development. However, evidence suggests that in manipulating PGE2, they unknowingly implicated 3alpha-hydroxysteroid dehydrogenase [E.C. 1.1.1.50], 3(or 17)alpha-hydroxysteroid dehydrogenase [E.C. 1.1.1.209] and their respective products, androsterone (ADT) and epitestosterone (EpiT), in the developmental masculinization of sex behavior. EpiT is generally regarded as a hormonally inactive 17alpha-epimer of testosterone (T). In rats, the kidney is the primary site of EpiT formation, whereas in humans it originates from the gonads, with only a small contribution secreted by the adrenals. Because the ratio of T to EpiT is nearly constant, it is presently used for assessing steroid abuse in competitive sports, where the World Anti-Doping Agency (WADA) considers a T/EpiT ratio >4 evidence of T doping. Despite its central role in the detection of illict anabolic steroid use, our knowledge of factors effecting EpiT production is poor. Clues in the literature, however, reveal that prostaglandin-mediated processes, such as LHRH release, may influence its production. Antimycotics, NSAIDs, and opioid analgesics used in sports medicine are all known to effect prostaglandin E2 synthesis. Primary PGs are potent inhibitors of ADT oxidation, while indomethacin, a prostaglandin blocker, powerfully inhibits 3alpha-HSD reduction and ADT oxidation. This is significant because ADT inhibits the oxidation of EpiT, and may modulate its antiandrogenic and neuroprotective effects. It is hypothesized that the T/EpiT ratio is increased by COX-2 inhibitors and opiod analgesics, and decreased by antimycotics that do not impair testosterone biosynthesis. Given the devastating personal and career consequences that may result from false positive drug tests, substantive research on the effects of PGE2 manipulations on EpiT is warranted.

Characterization of 17alpha-hydroxysteroid dehydrogenase activity (17alpha-HSD) and its involvement in the biosynthesis of epitestosterone

BACKGROUND

Epi-testosterone (epiT) is the 17alpha-epimer of testosterone. It has been found at similar level as testosterone in human biological fluids. This steroid has thus been used as a natural internal standard for assessing testosterone abuse in sports. EpiT has been also shown to accumulate in mammary cyst fluid and in human prostate. It was found to possess antiandrogenic activity as well as neuroprotective effects. So far, the exact pathway leading to the formation of epiT has not been elucidated.

RESULTS

In this report, we describe the isolation and characterization of the enzyme 17alpha-hydroxysteroid dehydrogenase. The name is given according to its most potent activity. Using cells stably expressing the enzyme, we show that 17alpha-HSD catalyzes efficienty the transformation of 4-androstenedione (4-dione), dehydroepiandrosterone (DHEA), 5alpha-androstane-3,17-dione (5alpha-dione) and androsterone (ADT) into their corresponding 17alpha-hydroxy-steroids : epiT, 5-androstene-3beta,17alpha-diol (epi5diol), 5alpha-androstane-17alpha-ol-3-one (epiDHT) and 5alpha-androstane-3alpha,17alpha-diol (epi3alpha-diol), respectively. Similar to other members of the aldo-keto reductase family that possess the ability to reduce the keto-group into hydroxyl-group at different position on the steroid nucleus, 17alpha-HSD could also catalyze the transformation of DHT, 5alpha-dione, and 5alpha-pregnane-3,20-dione (DHP) into 3alpha-diol, ADT and 5alpha-pregnane-3alpha-ol-20-one (allopregnanolone) through its less potent 3alpha-HSD activity. We also have over-expressed the 17alpha-HSD in Escherichia coli and have purified it by affinity chromatography. The purified enzyme exhibits the same catalytic properties that have been observed with cultured HEK-293 stably transfected cells. Using quantitative Realtime-PCR to study tissue distribution of this enzyme in the mouse, we observed that it is expressed at very high levels in the kidney.

CONCLUSION

The present study permits to clarify the biosynthesis pathway of epiT. It also offers the opportunity to study gene regulation and function of this enzyme. Further study in human will allow a better comprehension about the use of epiT in drug abuse testing; it will also help to clarify the importance of its accumulation in breast cyst fluid and prostate, as well as its potential role as natural antiandrogen.

Epitestosterone

Epitestosterone has been identified as a natural component of biological fluids of several mammals including man. For a long time it was believed that it is a metabolite without any hormonal activity and without any marked relationship to the hormonal state in health and disease. Neither the biosynthetic pathway nor the site of its formation in man have been unequivocally confirmed to date. It apparently parallels the formation of testosterone (T), but on the other hand its concentration is not influenced by exogenous administration of testosterone. This fact creates the basis of the present doping control of testosterone abuse. In 1989 an observation was presented in a dermatological study that epitestosterone exerts an effect counteracting the action of testosterone on flank organ of Syrian hamster. Further studies showed that a complex action consisting of competitive binding of epitestosterone to androgen receptor, of inhibition of testosterone biosynthesis and its reduction to dihydrotestosterone and of antigonadotropic activity could be demonstrated in rat, mice and human tissues. It can be presumed that epitestosterone as a natural hormone can contribute to the regulation of such androgen dependent events as, e.g. the control of prostate growth or body hair distribution.

Sex- and age-related changes in epitestosterone in relation to pregnenolone sulfate and testosterone in normal subjects

Epitestosterone has been demonstrated to act at various levels as a weak antiandrogen. So far, its serum levels have been followed up only in males. Epitestosterone and its major circulating precursor pregnenolone sulfate and T were measured in serum from 211 healthy women and 386 men to find out whether serum concentrations of epitestosterone are sufficient to exert its antiandrogenic actions. In women, epitestosterone exhibited a maximum around 20 yr of age, followed by a continuous decline up to menopause and by a further increase in the postmenopause. In men, maximum epitestosterone levels were detected at around 35 yr of age, followed by a continuous decrease. Pregnenolone sulfate levels in women reached their maximum at about age 32 yr and then declined continuously, and in males the maximum was reached about 5 yr earlier and then remained nearly constant. Epitestosterone correlated with pregnenolone sulfate only in males. In both sexes a sharp decrease of the epitestosterone/T ratio around puberty occurred. In conclusion, concentrations of epitestosterone and pregnenolone sulfate are age dependent and, at least in prepubertal boys and girls, epitestosterone reaches or even exceeds the concentrations of T, thus supporting its role as an endogenous antiandrogen. The dissimilarities in the course of epitestosterone levels through the lifespan of men and women and its relation to pregnenolone sulfate concentrations raise the question of the contribution of the adrenals and gonads to the production of both steroids and even to the uniformity of the mechanism of epitestosterone formation.

Free and conjugated estrogens and androgens in stallion semen

The steroid content of semen from a total of 11 mature fertile stallions was studied during two breeding seasons and one winter. The levels of free and conjugated substrates (testosterone and androstenedione), and products (estradiol and estrone), of aromatase were measured by radioimmunoassay with a validated method. The results were seasonally and monthly highly variable with characteristic peaks. The concentrations of free and conjugated estrogens were always higher in the gel-free ejaculate than in the gel except in one subfertile stallion used as comparison. Furthermore, the steroid production and the maximal resulting aromatase activity, estimated by the estrogens/androgens ratio, peaked in April-May and June. The breeding season (spring and summer) presents a clear estrogenic profile with estrogens/androgens ratios higher in contrast to the nonbreeding period (autumn and winter). The involvement of estrogens in the regulation of reproduction and equine spermatogenesis is discussed, and estrogens production and thus equine aromatase is proposed as a strong marker of testicular endocrine function.

Biochemical roles of testosterone and epitestosterone to 5 alpha-reductase as indicators of male-pattern baldness

In establishing a theory to predict male-pattern baldness, we investigated the correlation of testosterone, epitestosterone, and dihydrotestosterone with 5alpha-reductase in hair using gas chromatography-mass spectrometry. One hundred milligram hair samples were obtained from a group of balding subjects and their sons, as well as from a corresponding aged-matched, nonbalding group. The ratio of testosterone to epitestosterone was significantly greater (mean 46.41, p < 0.001; mean 35.83, p < 0.001, respectively) in the hair of balding fathers (n = 19, age 28-50 y) and their sons (n = 16, age 8-16 y) than in the hair of the nonbalding control subjects (mean 9.17 and 10.47, respectively). These findings demonstrate that analysis of terminal hair may not only provide a basis for predicting baldness when the subject is still young, but also for preventing and treating male-pattern baldness by controlling the steroid hormone balance.

Adrenal and gonadal contributions to urinary excretion and plasma concentration of epitestosterone in men--effect of adrenal stimulation and implications for detection of testosterone abuse

OBJECTIVE

The ratio of urinary testosterone (T) to epitestosterone (EpiT) is used to detect T abuse in sport. Also, plasma or urinary concentrations of EpiT have been measured to assess testicular steroidogenesis during hormonal male contraception. Further investigations are required to evaluate the relative contributions of the testis and adrenal to EpiT production. To this purpose, we have compared basal urinary EpiT glucuronide and plasma EpiT and the response to synthetic adrenocorticotrophic hormone (ACTH) stimulation between eugonadal and hypogonadal men.

DESIGN AND SUBJECTS

The basal urinary excretion rate of EpiT glucuronide was determined in 34 eugonadal men. Six men, clinically diagnosed as hypogonadal, and 6 out of the 34 eugonadal men previously described, received an intramuscular injection of synthetic ACTH depot (1 mg) at 0800 h on two consecutive days. Blood samples were collected prior to and then at 1.5, 8, 24, 25.5, 32 and 48 h with respect to the first administration (0 h). 24-h urine specimens were collected from 0800 h on days 1 and 2 (baseline) and 3 and 4 (stimulation).

MEASUREMENTS

Plasma EpiT, T and cortisol were measured by RIA and urinary EpiT and T, following glucuronide hydrolysis, by gas chromatography-mass spectrometry (extract combines aglycones with a minor amount of urinary free steroids).

RESULTS

Basal excretion rates of EpiT glucuronide in eugonadal men (range: 62-751 nmol/24 h) were considerably greater than in hypogonadal men (range: 3-34 nmol/24 h). Mean basal plasma EpiT in eugonadal men (1.32 +/- 0.08 nmol/l) were greater than in hypogonadal men (0.68 +/- 0.04 nmol/l). In each group, synthetic ACTH stimulation increased plasma cortisol 4-fold. In eugonadal men, plasma and urinary EpiT were unchanged whereas plasma and urinary T glucuronide decreased in response to ACTH. In hypogonadal patients, ACTH increased plasma and urinary EpiT while plasma T remained unchanged.

CONCLUSION

The testes are the major source of epitestosterone, the adrenal contribution being relatively modest. Following adrenal stimulation, urinary epitestosterone glucuronide increases considerably in hypogonadal men but this increase is masked in eugonadal men because testicular production is probably suppressed by the ACTH-induced rise in cortisol. Activation of the adrenal cortex results in no change or only a small decrease in the urinary T/EpiT ratio in eugonadal men.

The role of androgens in female vertebrates

The role of androgens in vertebrate females has been overlooked until recently. We examine the functional significance of androgens in females by reviewing studies that document relatively high levels of circulating plasma androgens, androgen receptors, or androgen-metabolizing enzymes in females. Among the mechanisms of androgenic action identified are enhanced neuron survival, stimulation of muscle satellite cell proliferation, alteration of ion current kinetics, and release of somatostatin. These mechanisms are not sex specific and thus we hypothesize that androgens play a significant role in normal female development. We encourage study in this nontraditional research area.

Primary immunolocalization of androgen target cells in the human anterior cruciate ligament

To identify androgen target cells in the human anterior cruciate ligament, immunohistochemical localization of the androgen receptor was performed in 31 specimens of the ligament. All of the specimens were obtained at surgery. Seventeen specimens were from women, and 14 were from men: the average age of the patients was 45.2 years (range: 18-78 years). An immunoperoxidase method using monoclonal antibodies to the androgen receptor was employed to identify androgen target cells in the ligament. Consistent staining of the androgen receptor was demonstrable in six specimens obtained from young men 18-24 years old, and equivocal positive staining was seen in two other specimens from young men. No receptors were demonstrated by this method in any of the specimens from women or older men. Androgen receptors were localized to synoviocytes in the synovium and under the synovial lining, fibroblasts in the ligament stroma, and cells lining the blood-vessel walls of the anterior cruciate ligament. The demonstration of androgen receptors in the cells of the anterior cruciate ligament strongly suggests that male sex hormones may have an effect on the structure and composition of this ligament in young men.