The effect of epitestosterone on the plasma levels of LH and FSH in ovariectomized immature rats

Liquid Chromatography-Mass Spectrometry-Based In Vitro Metabolic Profiling Reveals Altered Enzyme Expressions in Eicosanoid Metabolism

Background

Eicosanoids are metabolites of arachidonic acid that are rapidly biosynthesized and degraded during inflammation, and their metabolic changes reveal altered enzyme expression following drug treatment. We developed an eicosanoid profiling method and evaluated their changes on drug treatment.

Methods

Simultaneous quantitative profiling of 32 eicosanoids in liver S9 fractions obtained from rabbits with carrageenan-induced inflammation was performed and validated by liquid chromatography-mass spectrometry coupled to anion-exchange solid-phase purification.

Results

The limit of quantification for the devised method ranged from 0.5 to 20.0 ng/mg protein, and calibration linearity was achieved (R²>0.99). The precision (% CV) and accuracy (% bias) ranged from 4.7 to 10.3% and 88.4 to 110.9%, respectively, and overall recoveries ranged from 58.0 to 105.3%. Our method was then applied and showed that epitestosterone treatment reduced the levels of all eicosanoids that were generated by cyclooxygenases and lipoxygenases.

Conclusions

Quantitative eicosanoid profiling combined with in vitro metabolic assays may be useful for evaluating metabolic changes affected by drugs during eicosanoid metabolism.

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.

17 Alpha-oestradiol and 17 beta-oestradiol do not affect basal and follicle-stimulating hormone-stimulated inhibin B secretion by highly purified rat Sertoli cells

The effects of 17 alpha-oestradiol and 17 beta-oestradiol on basal and follicle-stimulating hormone (FSH)-stimulated inhibin B secretion by rat Sertoli cells were studied. Sertoli cells were isolated and cultivated from testes of 18-day-old Wistar rats in the presence and absence of FSH and different doses of oestrogens. On day 4 of culture, secreted inhibin was measured by enzyme-linked immunosorbent assay. Neither 17 alpha-oestradiol nor 17 beta-oestradiol had any effect on the secreted inhibin level in either the presence or absence of FSH. It is concluded that these oestradiols do not play an essential role in regulatory processes involving inhibin or FSH.

Concentration of the endogenous antiandrogen epitestosterone and androgenic C19-steroids in hyperplastic prostatic tissue

Epitestosterone (epiT, 17 alpha-hydroxy-4-androsten-3-one), an endogenous C19-steroid in humans, was considered for a long time as a physiologically inactive steroid. Recently, its antiandrogenic properties have been discovered. For the evaluation of its biological availability in the target organs the tissue concentration is of importance. EpiT, testosterone, dihydrotestosterone, and androstenedione concentrations in prostatic tissue were determined in 15 prostate samples obtained by suprapubic prostatectomy for benign prostatic hyperplasia. The steroids were extracted and separated by high-pressure liquid chromatography and determined by specific radioimmunoassay (RIA) methods. The concentration of epiT (mean 58.4 +/- 40.4 SD, range 14.0-144.0 fmol/mg protein) exceeded that of testosterone and was approximately as high as that of dihydrotestosterone. EpiT level increased with age and the correlation was significant (P < 0.05). It did not correlate significantly with testosterone but did with androstenedione and dihydrotestosterone (P < 0.05, each). As expected, a positive correlation was found between testosterone and dihydrotestosterone levels.

Inhibition of steroid 17 alpha-hydroxylase and C17,20-lyase in the human testis by epitestosterone

Epitestosterone (17 alpha-hydroxy-4-androsten-3-one) inhibited competitively 17 alpha-hydroxylation of pregnenolone and subsequent C17,20-side chain cleavage of resulting 17 alpha-hydroxypregnenolone using microsomal preparations from the human testis. The inhibition constants for 17 alpha-hydroxylase and C17,20-lyase with 5-ene-precursors of C21-steroids were 96 and 12.4 mumol/l, respectively.