Alteration in the normal pattern of serum testosterone and 5 alpha-androstane-3 alpha, 17 beta-diol in the immature male rat following chronic treatment with luteinizing hormone releasing hormone or luteinizing hormone

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.

Effects of mGnRH on testicular steroidogenesis in the toad Bufo arenarum

GnRH controls vertebrate reproduction in several ways. This hormone not only affects the secretion of gonadotropins from the pituitary gland but also has a direct influence on several gonadal functions such as steroidogenesis, spermatogenesis, and spermiation. In the present paper we have studied the in vitro effects of GnRH on the testicular steroidogenesis of Bufo arenarum to ascertain the role of this peptide in the control of the steroidogenic pathway previously described in this species. It was found that GnRH is able to reduce basal as well as hCG-stimulated testosterone release, having an inhibitory effect on P450(c17) activity. Thus, GnRH could be involved in the mechanism that regulates the metabolic change in the testicular steroidogenesis. Additionally, testicular GnRH binding site has been characterised, showing a K(d) of 34 nM and a maximum binding of 4.7 pmol/mg protein.

Steroid metabolism in gonads of turtle embryos as a function of the incubation temperature of eggs

In embryos of many reptiles, the sexual differentiation of gonads is temperature-dependent. In the turtle Emys orbicularis, all individuals become phenotypic males at 25 degrees C, whereas 100% phenotypic females are obtained at 30 degrees C. Steroid metabolism in embryonic gonads was studied at both temperatures, during and after the thermosensitive period for sexual differentiation. Pools of gonads were incubated for various times, with 3 beta-hydroxy-5-pregnen-20-one (pregnenolone), progesterone, dehydroepiandrosterone or 4-androstene-3,17- dione as substrates. The analysis of metabolites combined two successive chromatographies (HPLC and TLC) and autoradiography. Conversion of pregnenolone to progesterone and of dehydroepiandrosterone to 4-androstene-3,17-dione was more important in testes at 25 degrees C than in ovaries at 30 degrees C. In ovaries, a large amount of 5-pregnene- 3 beta,20 beta-diol was formed from pregnenolone, and 5-androstene-3 beta,17 beta-diol was produced from dehydroepiandrosterone. In both testes and ovaries, 5 alpha-pregnane and 5 alpha-androstane derivatives were the main metabolites obtained from progesterone and 4-androstene-3,17-dione, respectively. Progesterone was also converted to 20 beta-hydroxy-4-pregnen-3-one. Dehydroepiandrosterone and 4-androstene-3,17-dione were also metabolized into 11 beta-hydroxy-4-androstene-3,17-dione (only in testes), testosterone, 11 beta,17 beta-dihydroxy-4-androstene-3-one, 17 beta-hydroxy-4-androstene-3,11-dione (low amounts in testes, traces in ovaries), 17 alpha-hydroxy-4-androstene-3-one, estrone and estradiol-17 beta (traces).

Regulation of 5 alpha-reductase activity in cultured immature leydig cells by human chorionic gonadotropin

The present studies examined the hormonal regulation of 5 alpha-reductase activity in cultured immature rat Leydig cells. Within the testis 5 alpha-reductase was concentrated in the interstitial cell compartment, and among interstitial cells, the enzyme was localized primarily in Band 3 of Percoll density gradients, which contains the majority of Leydig cells. Among various factors reported previously to stimulate testicular 5 alpha-reductase activity when administered in vivo to immature rats (LH/hCG, FSH, luteinizing hormone releasing hormone or prolactin), only LH/hCG directly stimulated 5 alpha-reductase activity of cultured immature Band 3 cells. Neither growth hormone which was reported previously to stimulate hepatic 5 alpha-reductase activity, nor insulin, insulin-like growth factor-I, or epidermal growth factor, which have been reported to modulate Leydig cell function, had any effect on 5 alpha-reductase activity of Band 3 cells. These studies suggest that the major factor directly stimulating 5 alpha-reductase activity in Leydig cells during early maturation is LH. However, it is possible that other factors acting indirectly may modulate the maturational rise in 5 alpha-reductase activity.

Characteristics of flutamide action on prostatic and testicular functions in the rat

The effect of daily treatment with the pure antiandrogen Flutamide has been studied either alone or in combination with the LHRH agonist [D-Trp6, des-Gly-NH2(10)]LHRH ethylamide (LHRH-A), on testicular and prostatic functions in adult male rats. Treatment for 10 days with Flutamide (5 mg/rat, twice daily) caused a marked stimulation of plasma testosterone (T) associated with a significant increase in plasma gonadotropin concentrations and inhibited plasma PRL levels. Testicular weight is not changed following antiandrogen administration but testicular LH/hCG receptor levels are markedly decreased with no change in FSH receptor levels. Moreover, Flutamide treatment alone produces an important inhibition of ventral prostate and seminal vesicle weights associated with a significant decrease in prostatic beta-adrenergic receptor levels but no change is observed in specific ornithine decarboxylase (ODC) activity. Daily LHRH-A treatment at the dose of 1 microgram/day for 10 days decreases plasma T to levels comparable to those found in orchiectomized men (0.30 +/- 0.5 ng/ml). This effect is associated with an almost complete loss of testicular LH/hCG receptors, a decrease in testicular weight, a significant increase in plasma gonadotropins and a marked inhibition of plasma PRL concentration. A relatively smaller inhibition of ventral prostate and seminal vesicle weights follows treatment with the LHRH agonist alone, this effect being accompanied by a significant reduction in beta-adrenergic receptor concentration but no change in prostatic ODC activity. Combination of the two drugs, however, caused a potent inhibitory effect on both ventral prostate and seminal vesicle weight to values similar to those found in castrated rats. The prostatic weight loss is accompanied by a marked fall in ODC activity and in the concentration of beta-adrenergic receptors. The present data clearly show that combined treatment with an LHRH agonist and a pure antiandrogen is highly effective in inhibiting, not only prostatic growth, but also two androgen-sensitive parameters of prostatic activity.

Effects of chronic administration of LH releasing hormone on age-dependent activities of testicular 4-ene-5 alpha-reductase and 17 beta-ol-dehydrogenase in mice

Male (WB X C57BL/6)F1 hybrid mice of 16, 26 and 66 days of age, 4 in each group, were injected daily with 0.2 micrograms/10 g body weight of LH releasing hormone (LHRH) or saline for 14 days. Testicular homogenates were incubated with [14C]4-androstene-3,17-dione and enzyme activities were examined. In mice treated with saline, testicular 17 beta-ol-dehydrogenase activity increased with age but 4-ene-5 alpha-reductase (5 alpha-reductase) activity decreased with age. LHRH treatment for 14 days starting from day 26 resulted in a delay in sexual maturation, as evidence by significant decreases (P less than 0.05) in seminal vesicle weight and testicular 17 beta-ol-dehydrogenase activity and by a significant increase (P less than 0.05) in 5 alpha-reductase activity. However, LHRH treatment starting from day 66 had no significant effect on these testicular enzyme activities.

Specificity of the direct effect of an LHRH agonist on testicular 17-hydroxylase but not on 5 alpha-reductase activity in hypophysectomized adult rats

The direct effect of treatment with a potent LHRH agonist on testicular steroidogenesis was studied by incubation of radioactive steroids with a testicular homogenate or with a suspension of interstitial cells obtained following 7 days of treatment of adult hypophysectomized male rats. The animals received [D-Ser(tBu)6,des-Gly-NH2(10)]LHRH ethylamide (25 micrograms) administered 3 times a day, hCG (5 or 25 IU) once daily or a combination of both drugs. The metabolism of tritiated progesterone into delta 4-metabolites by a suspension of interstitial cells was markedly reduced by treatment with the LHRH agonist (LHRH-A) alone or following combined treatment with hCG and LHRH-A. No formation of 5 alpha-reduced steroids was detected in the medium following incubation with testicular homogenate or interstitial cells. Similar findings were obtained by measurement of testicular steroid content. The present data demonstrate that the direct effect of the LHRH agonist is limited to the Leydig cells on 17-hydroxylase activity. This inhibitory effect is reflected by an accumulation of testicular pregnenolone and progesterone content and a marked inhibition of progesterone metabolism into delta 4-androgens. However, no stimulation of 5 alpha-reductase, an enzyme localized in seminiferous tubules, could be detected. Such data show clear differences between the direct and the pituitary-mediated effects of treatment with LHRH agonists on testicular steroidogenesis. While the LHRH agonist administered at high doses in the rat can directly inhibit 17-hydroxylase activity, the stimulatory effect on 5 alpha-reductase activity is regulated by another mechanism.

Steroid biosynthesis in turtle testes

Testicular metabolism of radiolabelled substrates (pregnenolone, progesterone and androstenedione) was examined in two species of turtles, Pseudemys scripta and Sternotherus odoratus. Chemical methods (chromatography, derivative formation and crystallization) identified testosterone (in both species) and 5 alpha-androstane-3 beta,17 beta-diol (in S. odoratus) as products. Tentative identifications were also made of 20 beta-hydroxypregn-4-en-3-one in both turtles. Chromatographic profiles indicated the presence of several other C19- and C21-steroids. In S. odoratus, changes in proportions of the two major C19-compounds (testosterone and the 5 alpha-androstanediol) suggest a "switch" in the enzymatic pathways which resembles that associated with maturation in the rat. This enzymatic switch may be associated with the annual testicular cycle of the adult turtle.

Changes with age in activities of 4-ene-5 alpha-reductase, 17 beta-ol-dehydrogenase and 17-hydroxylase in normal and neonatally grafted mouse testes

Male and female (WB X C57BL/6)F1 hybrid mice of various ages were used. Two testes from mice at day 0 after birth were grafted under the capsule of the right kidney of male, female and castrated male mice at 80-100 days of age, and the grafted testes in groups of 12-24 were removed 15-120 days after grafting. Normal testes of various ages were also used. Testicular homogenates were incubated with [3H]progesterone or [14C]4-androstene-3,17-dione, and enzyme activities per g tissue were estimated. Activities of 17-hydroxylase and 17 beta-ol-dehydrogenase increased significantly with age in the normal testes and in the grafted testes in the males, females and castrated males; the most conspicuous increases in activities of 17-hydroxylase and 17 beta-ol-dehydrogenase were found, respectively, from 15 days of age to 30 days and from 30 days to 40 days. In contrast, 5 alpha-reductase activity was the highest at 30 days of age, moderately high at 15 and 40 days and very low at 60 and 120 days in the normal testes as well as in all grafted testes examined under various endocrine conditions, though the peak value at 30 days was significantly higher in the normal testes than in the grafted ones. These results seem to indicate that changes with age in 5 alpha-reductase activity relative to other enzyme activities in mouse testes are at least in part an autonomous process related to the period of gonadotropin stimulation or age of the Leydig cells.

Recovery of gonadal functions in the adult male rat following cessation of five-month daily treatment with an LHRH agonist

This study describes the recovery of various parameters of the pituitary-gonadal axis following five months of daily treatment of adult male rats with a potent LHRH (luteinizing hormone-releasing hormone) agonist. Two-month-old male rats were treated daily with either 250 ng or 1 microgram of [D-Ser(TBU)6, des-Gly-NH2(10)]LHRH ethylamide (LHRH-A) s.c. for five months. At the end of treatment, prostate weights were within normal limits and seminal vesicle weights were only slightly decreased. While normal values were found three months following cessation of treatment, it was observed, somewhat unexpectedly, that ventral prostate and seminal vesicle weights were increased by 66 and 54%, respectively, five months after cessation of treatment with the 1 microgram daily dose of LHRH-A. Immediately following the five-month treatment period with either dose of the LHRH agonist, basal testicular levels of pregnenolone, progesterone (P), 17-OH-progesterone (17-OH-P), androstenedione, testosterone, androstane-3 beta,17 beta-diol and androst-5-ene-3 beta, 17 beta-diol were decreased, while the concentrations of dihydrotestosterone (DHT), androstane-3 alpha, 17 beta-diol (3 alpha-diol) and 17 beta-estradiol were increased. Three months following cessation of treatment, all basal testicular steroid levels had returned to normal except pregnenolone, P, 17-OH-P and androstenedione, which were still reduced by 40 to 60%. Five months following cessation of treatment, on the other hand, basal levels of all testicular steroids were 40 to 200% increased in the animals having received either dose of the LHRH agonist. The testicular steroidogenic responsiveness was measured 2 hours following the subcutaneous administration of 10 micrograms oLH. Following five months of daily treatment with the LHRH agonist, the main findings are a decreased response of pregnenolone, P, 17-OH-P and androst-5-ene-3 beta, 17 beta-diol, and an increased DHT, 3 alpha-diol and androstane-3 beta, 17 beta-diol responsiveness. Three months post-treatment, on the other hand, particularly at the higher dose of LHRH agonist, there was an increased responsiveness of androstenedione, T, DHT and 3 alpha-diol, a finding which was maintained after two additional months of recovery. Degenerative changes were observed in most tubules following five months of LHRH-A treatment. While most tubules returned to normal five months later, some tubules still showed degenerative changes. Plasma LH measured by radioimmunoassay (RIA) was elevated after five months of treatment with the daily 1 microgram dose, but all other values were within normal limits.(ABSTRACT TRUNCATED AT 400 WORDS)

Delay in the age of balano-preputial skinfold cleavage and alterations in serum profiles of testosterone, 5 alpha-androstane-3 alpha,17 beta-diol, and gonadotropins in adult rats treated during puberty with luteinizing hormone releasing hormone

Previous work has shown that chronic treatment of intact, immature male rats with luteinizing hormone releasing hormone (LHRH) decreases sex accessory gland weights and results in retardation of the normal developmental increase in the ratio of serum testosterone (T)/5 alpha-androstane-3 alpha,17 beta-diol (3 alpha-Diol) via an apparent enhancement of testicular 5 alpha-reductase or 3 alpha-hydroxysteroid oxidoreductase activities. In the present work, androgen dependent balano-preputial skinfold cleavage was significantly delayed by approximately one week in intact, immature male rats which were treated daily for two weeks with either 1.0 micrograms, 2.5 micrograms or 5.0 micrograms of LHRH during a discrete phase of pubertal development (28-41 days of age). In intact, adult (62 day old) animals which received LHRH treatments during pubertal development, serum T concentrations and sex accessory gland weights were reduced compared to control animal values. Serum 3 alpha-Diol content in the adult rats was either unaltered or increased significantly depending on the LHRH dosage employed during sexual development. Serum luteinizing hormone concentrations were not different between control and LHRH-pretreated adult rats whereas the highest dosage of LHRH employed (5.0 micrograms) during puberty resulted in a significant elevation of adult serum follicle stimulating hormone levels. It is suggested that chronic LHRH treatment of the male rat during puberty results in a perturbation in testicular androgen biosynthetic activities and an impairment of pituitary-testicular hormone feedback mechanisms which persist at least through early adulthood.

Comparative effects of LHRH agonist and ovine LH administration on testicular steroidogenesis in intact adult rat

In order to better understand the effects of LHRH administration on testicular function in adult rat, we compared the inhibitory effects of LH and LHRH analogue [D-Ser-(TBU)6, des-Gly-NH2(10)]LHRH ethylamide upon testicular steroidogenesis and LH, FSH and prolactin receptor contents. Administration of LH as well as LHRH analogue resulted in a marked decrease of LH receptor levels, accompanied by a blockage at the level of 17-hydroxylase activity. We have been able to demonstrate that multiple LH administration can achieve a testicular desensitization comparable to that observed after LHRH agonist treatment.

Combined long-term treatment with an LHRH agonist and a pure antiandrogen blocks androgenic influence in the rat

Daily administration for 5 months of the potent LHRH agonist (D-Ser(TBU)6, des-Gly-NH2(10)) LHRH ethylamide (250 ng) in combination with the pure antiandrogen RU23908 (5 mg) to adult male rats causes a marked inhibition of ventral prostate and seminal vesicle weight to 9% and 15% of control, respectively. At the doses used, owing to readjustments of the pituitary-testicular axis, neither treatment alone has an effect on prostate weight and exerts only minimal inhibitory effects on seminal vesicle weight. Whereas treatment with the LHRH agonist alone markedly inhibits testicular LH and PRL receptor levels, the antiandrogen alone stimulates the concentration of the two receptors and reverses the inhibitory effect of the LHRH agonist treatment on LH receptors. Treatment with the LHRH agonist decreases plasma PRL levels, whereas the antiandrogen increases the concentration of circulating LH and FSH by 250%. Treatment with the LHRH agonist decreases the concentration of testosterone and its precursors of the delta 4-pathway while stimulating 5 alpha-reductase activity in both the absence and presence of simultaneous treatment with the antiandrogen. The present data show that blockage of the delta 4-steroidogenic pathway induced by treatment with an LHRH agonist prevents the escape phenomenon observed during long-term treatment with a pure antiandrogen, and permits maximal inhibitory effects of the two treatments on secondary sex organ weight. Such combined treatment with an LHRH agonist (to block androgen formation) and an antiandrogen (to neutralize remaining androgens of testicular and adrenal origin) should be the hormonal therapy of choice in prostatic carcinoma.