Formation in vitro of 5alpha-dihydrotestosterone and other 5alpha-reduced metabolites of 3H-testosterone by the seminiferous tubules and interstitial tissue from immature and mature rat testes

Patterns of peripheral steroid metabolism vary with sex, season, and tissue type in blotched blue-tongued lizards (Tiliqua nigrolutea)

We examined sexual and seasonal variation in the ability of reproductively relevant tissues (liver, skin, adrenal gland, cloaca, kidney, renal sexual segment, epididymis, oviduct, muscle, testis, and ovary) to metabolise a primary steroid [testosterone (T) or estradiol (E2)] in the scincid lizard, Tiliqua nigrolutea. We observed considerable variation between sexes and across seasons in the patterns of conjugation and derivatisation of the primary steroids by these tissues. All tissues demonstrated the ability to conjugate the relevant primary steroid. Other general trends included increased conjugation by all tissues of gestating females, reduced metabolism of E2 by female tissues during late vitellogenesis, and reduced metabolism of T by males during early spermatogenesis. 5alpha-Dihydrotestosterone was the most commonly detected derivative in males, and production varied with season and tissue type. We suggest that seasonal variation in the ability of reproductively relevant tissues may be important in the physiological regulation of reproduction in this species.

5alpha-reductase isoenzymes 1 and 2 in the rat testis during postnatal development

The pubertal initiation of spermatogenesis is reliant on androgens, and during this time, 5alpha-reduced androgens such as dihydrotestosterone (DHT) are the predominant androgens in the testis. Two 5alpha-reductase (5alphaR) isoenzymes (5alphaR1 and 5alphaR2) have been identified, which catalyze the conversion of testosterone to the more potent androgen DHT. The present study aimed to investigate the developmental pattern of 5alphaR isoenzymes and their relationship to the production of 5alpha-reduced androgens in the postnatal rat testis. Both 5alphaR1 and 5alphaR2 isoenzyme mRNAs were measured by real-time polymerase chain reaction, isoenzyme activity levels by specific assays, and testicular androgens by radioimmunoassay after high-performance liquid chromatographic separation. Both 5alphaR1 and 5alphaR2 mRNAs and activity levels were low in the 10-day-old (prepubertal) testis, peaked between Days 20 and 40 during puberty, and then declined to low levels at 60-160 days of age. The developmental pattern of both 5alphaR isoenzyme activity levels was mirrored by the testicular production of 5alpha-reduced metabolites. Although 5alphaR1 was greater than 5alphaR2 at all ages, it is likely, given the substrate preferences of the two, that both isoenzymes contribute to the pubertal peak of 5alpha-reduced androgen biosynthesis. The peak in 5alphaR isoenzymes and 5alpha-reduced metabolite production coincided with the first wave of spermatogenesis in the rat, suggesting a role for 5alpha-reduced metabolites in the initiation of spermatogenesis. This was explored by acute administration of a 5alphaR inhibitor (L685,273) to immature rats. The L685,273 markedly suppressed testicular 5alphaR activity during puberty by 75%-86%. However, a marked increase was observed in testicular testosterone levels (in the absence of changes in LH), and no decrease was observed in the absolute levels of 5alpha-reduced metabolites. Therefore, whether the formation of DHT in the presence of low testosterone levels in the pubertal testis is required for the initiation of spermatogenesis cannot be tested using 5alphaR inhibitors. We conclude that both 5alphaR1 and 5alphaR2 isoenzymes are involved in the peak of 5alpha-reduced androgen biosynthesis in the testis during the pubertal initiation of spermatogenesis.

Enzyme assay for 5alpha-reductase type 2 activity in the presence of 5alpha-reductase type 1 activity in rat testis

The relative abundance and physiological role of 5alpha-reductase (5alphaR) isoforms in rat testis, in particular 5alpha-reductase Type 2 (5alphaR2) are poorly understood. Investigation of 5alphaR2 activity using enzyme kinetic studies was hampered by the high concentrations of 5alpha-reductase Type 1 (5alphaR1) in rat testis. Therefore, an assay was developed which exploited the differences in pH optima of the two isoforms. The 5alphaR assays measured the conversion of 3[H]-testosterone to 5alpha-reduced metabolites (dihydrotestosterone+3alpha-Androstanediol) at pH 5.0 and 7.0. To compensate for the overlap of 5alphaR1 activity at pH 5.0, the amount of 5alphaR1 activity at pH 5.0 was determined by measuring recombinant rat 5alphaR1 expressed in COS-7 cells at pH 5.0 and 7.0. The amount of activity at pH 5.0 that was attributed to 5alphaR1 was determined to be 12.4+/-1.4% (mean+/-S.D., n=14). The 5alphaR2 assay was validated by determining recombinant rat 5alphaR2 activity in the presence of recombinant rat 5alphaR1 activity in COS cells. A 99.3+/-14.7% recovery of 5alphaR2 activity was obtained when comparing 5alphaR2 activity recovered versus activity added. 5alphaR1 and 5alphaR2 activities were then assayed in rat testis extracts from 30, 75 and 147 days. Both isoforms markedly declined (50-100-fold) over this age range, with 5alphaR1 as the predominant isoform. In conclusion, an enzymatic assay that detects 5alphaR2 activity in the presence of high concentrations of 5alphaR1 was developed and is applicable in the measurement of 5alphaR2 activity in rat testis.

Stage-related changes in steroid-converting enzyme activities in Squalus testis: synthesis of biologically active metabolites via 3 beta-hydroxysteroid dehydrogenase/isomerase and 5 alpha-reductase

To investigate the relationship between steroidogenesis and spermatogenesis, two key enzymes of androgen biosynthesis, 3 beta-hydroxysteroid dehydrogenase/isomerase (3 beta-HSD) and 5 alpha-reductase, were compared at premeiotic (PrM), meiotic (M), and postmeiotic (PoM) stages. Staged tissues were obtained by dissection from the testis of the spiny dogfish Squalus acanthias, in which spermatogenesis is a simple diametric progression. Microsomal 3 beta-HSD activity was measured by conversion of [3H]dehydroepiandrosterone (DHEA) to androstenedione (AE). Reaction constants were: Km = 3.2 microM and Vmax = 243 pmol/min/mg protein. 3 beta-HSD increased progressively with maturation, resulting in three- to four-fold higher levels in PoM than in PrM stages. Absolute values and stage-related differences were the same, whether microsomes were derived from whole testis or from isolated spermatocysts (germ cell/Sertoli cell units), thus supporting microscopic studies showing that Sertoli cells are the primary steroidogenic elements of dogfish testis. In vitro conversion of [3H]testosterone to [3H]dihydrotestosterone (DHT) was used to estimate 5 alpha-reductase activity. Apparent substrate affinity was similar to that of 3 beta-HSD (Km = 2.9 microM), but maximal product yields were two to three orders of magnitude lower (Vmax = 208 fmol/min/mg protein). Also, the stage-related pattern of 5 alpha-reductase activity (PrM > PoM >> M) differed from that of 3 beta-HSD (PoM >> M > PrM).(ABSTRACT TRUNCATED AT 250 WORDS)

Sex steroids levels in the plasma and testis during the reproductive cycle of lizard Podarcis s. sicula Raf

Progesterone (P), 17-OH-progesterone (17-OH-P), androstenedione (A), dehydroepiandrosterone (DHEA), testosterone (T), 5 alpha-dihydrotestosterone (5 alpha-DHT), and 17 beta-estradiol (E2) were measured by RIA in plasma and testes of 114 males of the oviparous lizard Podarcis s. sicula raf, a species that displays annual hibernating cycles. Hormones were determined each month from January until December, except for August. Testosterone peaked at 174.8 ng/ml of plasma after emergence (March), while 5 alpha-DHT and A peaked in April. Plasma DHEA increased during hibernation. During the refractory period there were progressive increases in P and E2 plasma levels. The testicular peak of T, in March, coincided with that observed in plasma. The striking increases in testicular T and A in early July occurred at a time when plasma androgen concentrations were low. 5 alpha-DHT increased in April when spermatogenesis with spermiation occurred and then decreased alongside a second peak of T. There is an apparent separation of plasma and testicular androgen concentrations during the reproductive cycle.

Testicular autoregulation: possible role for 7-alpha-hydroxylated androgens

Pituitary FSH secretion appears to be supported by a factor distinct from the gonadotropin-releasing hormone (Gn-RH). The ratio of FSH to LH is positively correlated with testicular steroid 5 alpha-reductase activity and negatively correlated with testicular steroid 7 alpha-hydroxylase under various experimental conditions. Literature describing interactions among the above and other factors is reviewed here.

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.

Quantitative assessment of the biological effects of follicle regulatory protein on dihydrotestosterone-maintained spermatogenesis in hypophysectomized rat

Follicle regulatory protein (FRP) isolated from porcine ovarian follicles influences folliculogenesis through a paracrine mechanism. A similar protein has been found in the testes and seems to have some inhibitory effects on spermatogenesis when administered to intact male experimental animals. On the basis of female and male studies, it has been ascertained that the effects of FRP are at the level of gonads and not the pituitary or the hypothalamus. In the studies with intact males it was not possible to determine the exact site of FRP action on the testes. Dihydrotestosterone (DHT) has been shown to maintain spermatogenesis in hypophysectomized rats. In order to determine if the inhibitory effects of FRP are at steps prior to the formation of DHT, FRP was administered to hypophysectomized rats that were injected with DHT. Groups of adult rats were hypophysectomized and treated daily with FRP, DHT, FRP + DHT, or vehicle alone for 30 days. At necropsy, body, testes, prostate glands, and seminal vesicle weights were recorded. One testis and sexual accessory glands were fixed for histological evaluation. The contralateral testis was decapsulated, six 2 mm segments of seminiferous tubules, representing defined stages of spermatogenesis, were isolated by transillumination-assisted microdissection, and spermatogenic cells were quantified by DNA flow cytometry. Histologically, the seminiferous tubules of vehicle-treated hypophysectomized controls showed advanced regression. Rats treated with FRP alone showed similar degeneration. On the other hand, rats treated with DHT showed maintenance of spermatogenesis comparable to normal controls. The testes of rats treated with FRP + DHT were indistinguishable from those treated with DHT only. Flow cytometric quantification of germinal cells from all groups confirmed the histological findings. In this study FRP did not exert deleterious effects on DHT-maintained spermatogenesis. This finding suggests that the inhibitory effects of FRP on spermatogenesis in intact animals may not be a direct effect on spermatogenic cells but may impair androgen action or production or DHT formation.

Hyperprolactinemia enhances LH-stimulated 4-ene-5 alpha-reductase activity but inhibits LH-induced 17-hydroxylase activity in testes of hypophysectomized immature rats

Two pituitaries from 7-week old female rats (Sprague-Dawley strain) were grafted under the capsule of the left kidney of 21-day old male rat. The pituitary grafted and sham-operated rats were hypophysectomized at 27 days of age. The hypophysectomized rats, in groups of 4, were given daily injections of 9 micrograms NIAMDD-oLH-23 (minimum effective dose) or saline for 3 days starting from day 29. Testicular homogenates were incubated with [3H]progesterone or [14C]4-androstene-3,17-dione, and enzyme activities per testes were estimated. Testicular HCG-binding sites were also measured. Hypophysectomy caused significant decreases in activities of testicular 5 alpha-reductase, 17-hydroxylase, and 17 beta-hydroxysteroid oxidoreductase. These decreased enzyme activities were significantly stimulated by LH treatment. Although pituitary grafts alone showed no effects on these enzyme activities in the testes of the hypophysectomized rats, the grafts significantly enhanced LH-stimulated 5 alpha-reductase activities but inhibited LH-stimulated 17-hydroxylase activity. Testicular LH/HCG receptors were significantly increased by the grafts, especially in the presence of LH, without affecting affinity for HCG. The present results demonstrate for the first time that hyperprolactinemia directly stimulates LH-stimulated 5 alpha-reductase activity in rat testes. The results also show that the same grafts directly inhibit LH-stimulated 17-hydroxylase activity, probably via postreceptor mechanisms.

Hormonal regulation of activities of 4-ene-5 beta- and 5 alpha-reductases and 17 beta-hydroxy-dehydrogenase in immature golden hamster testis

We have reported [1-3] in immature golden hamster testis that 5 beta-reductase is localized in the tubular nongerm cells, while 5 alpha-reductase is present in the interstitial tissue and that the 17 beta-hydroxy-dehydrogenase activity is found predominantly in the tubular nongerm cells. Hormonal regulation of these enzyme activities was examined in the present study. Male golden hamsters were hypophysectomized on day 22 after birth. The hypophysectomized hamsters in groups of 3-8 were injected daily with 10 micrograms NIH-LH-S19, 50 micrograms NIAMD-Rat-FSH-B-1, 8 or 16 micrograms NIAMD-oFSH-13, 8 micrograms NIAMD-oFSH-13 plus 5 or 10 micrograms NIH-LH-S19, 1 mg testosterone propionate or saline for 5 days starting from day 23. Testicular homogenates of the treated hamsters and intact hamsters on day 28 were incubated with [14C]4-androstene-3,17-dione and NADPH, and enzyme activity (nmol/testes/h) was estimated. The activities of 5 beta- and 5 alpha-reductases and 17 beta-hydroxy-dehydrogenase decreased significantly 6 days after hypophysectomy. In the hypophysectomized hamster testis, a distinct response to FSH but not to LH in the activities of 5 beta-reductase and 17 beta-hydroxy-dehydrogenase was found. The injection of LH in addition to FSH showed no significant additive effects on these enzyme activities. The 5 alpha-reductase activity was stimulated significantly by LH plus FSH but not by LH alone, FSH alone or androgen. These results show that 5 beta-reduction of 4-ene-3-ketosteroids takes place in the Sertoli cells under the influence of FSH while 5 alpha-reduction occurs in the interstitial cells under the influence of LH and FSH in immature hamster testis.

Effects of testosterone and its metabolites in relation to androgen-binding activity in murine submandibular salivary glands

The relative potencies of testosterone (T), testosterone propionate (TP) and other related steroids (5 alpha-dihydrotestosterone, DHT; 5 alpha-androstane-3 alpha, 17 beta-diol, alpha-diol; 5 alpha-androstane-3 beta, 17 beta-diol, beta-diol) in restoring some morphological and functional characteristics of submandibular gland (SMG) were investigated in castrated mice. The steroids restored to near-control values the glandular weight and total protein content, alpha-diol and TP being the most effective compounds tested; with regard to proteolytic activity stimulation, beta-diol was more effective than DHT. The alpha-diol metabolite was unique in significantly increasing DNA synthesis. In competition studies, alpha-diol and beta-diol were ineffective in displacing the specifically bound [3H]-R1881 from the SMG androgen-binding macromolecules. Thus T can elicit its effects on SMG without the need of prior conversion to DHT; there must be alternative, receptor-independent mechanisms whereby alpha- and beta-diol exert trophic/metabolic effects on murine SMG.

Androgen concentrations in testicular and peripheral blood in the male Japanese quail

Two experiments were conducted in which the concentrations of testosterone and dihydrotestosterone (DHT), an active metabolite of testosterone, were studied in the general circulation and in the testicular effluent. In the first experiment, blood samples taken from adult male quail were analyzed by radioimmunoassay for androgen and DHT concentrations; from these data, testosterone concentrations were calculated. The average concentration of androgen was 4238 pg/ml plasma. The average ratio of DHT/testosterone was .75. In the second experiment, steroid concentrations were compared in blood samples taken from the testicular vein and from the general circulation. Androgen concentrations in the general circulation were 36% of that obtained for the testicular effluent. In addition, testosterone and DHT concentrations in the general circulation were 36 and 46%, respectively, as high as concentrations in the testicular vein. Comparison of the average ratios of testosterone/DHT in the general versus testicular plasma revealed a higher ratio in the general circulation (.73 vs. .51, respectively). These results provide additional evidence for testosterone as the major male steroid secreted by the gonads. In addition, the relative concentration of DHT in the quail, which is higher than documented for most species, was higher in the peripheral than in the testicular circulation. This may indicate peripheral metabolism of testosterone to its active metabolite, DHT, and could have implications as to the availability of DHT for its target tissues.

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.

Testosterone metabolism by testicular tissue

Teased testicular tissue with defined cell populations from experimental rats, as well as testicular tissue from normal rats, was incubated in an environment that insured the morphologic integrity of the tissue at the conclusion of the experiment. In cryptorchid animals, conversion of available substrate to various metabolites by testicular tissue comprised of Leydig and Sertoli cells was comparable to that of intact controls. Using hypophysectomized and hypophysectomized-cryptorchid rats, reliably measurable androgen metabolites were produced by testicular tissue that had specific populations of intact cell types. The reported methodology shows that defined cell populations, capable of testosterone metabolism, can be obtained in vivo by surgical procedures. Histologic monitoring of the tissue at the conclusion of the incubation has helped define the best environment for the maintenance of morphologic integrity throughout the incubation period. These techniques will allow future work on quantitative assessment of testosterone metabolism by defined cell populations of the testis.

Effect of antigonadotropic sera on in vitro testicular metabolism of 3H-testosterone in immature rats

Male rats were daily injected from the 5th day to the 21st day of life with purified rabbit anti-FSH serum, or anti-LH serum. After the last injection, they were killed and the testes incubated in vitro with 3H-testosterone. The radioactive metabolites were separated and identified by a double isotope dilution method. In rats treated with antigonadotropic sera, the total amount of 5 alpha-reduced metabolites was significantly decreased. The profile of the 5 alpha-reduced metabolites obtained in the anti-FSH treated group was different from those obtained in control and anti-LH treated groups. Antigonadotropic sera modify the in vitro metabolism of testosterone by the testicular tissue.

Role of testosterone levels and of hypophysis in the HCG-induced modifications of the 7 alpha-hydroxylation and 5 alpha-reduction processes in incubated rat testes

The role of a direct or a hypophysis-mediated influence of increased testosterone levels in the effects of a long-term high-dose HCG administration (10 IU/day) upon the 7 alpha-hydroxylation and 5 alpha-reduction activities of incubated testes of mature rats was investigated. Administration of high doses of HCG to hypophysectomized rats resulted in the same metabolic changes as in normal rats, namely, a large decrease in the 7 alpha-hydroxylation and an increase in the 5 alpha-reduction processes. Administration of testosterone-propionate (0.2 mg and 20 mg/day) for several days to hypophysectomized rats and to normal rats receiving and substitutive dose of 1 IU HCG/day, did not modify the testicular metabolization pattern. These findings indicate that the decrease in testicular 7 alpha-hydroxylation activity induced by long-term administration of high doses of HCG is probably not mediated by the hypophysis nor by the extracellular testosterone levels.

Modulation of steroidogenic activities in testis Leydig cells

Recent developments in the regulation of testicular Leydig-cell function support the following conclusions. (1) Enzymic activities involved in steroid production in the testis are mainly localized in Leydig cells. The aromatase enzyme complex for oestrogen production appears to be localized in Leydig cells as well as in Sertoli cells. (2) LH- (or hCG-) induced alterations of Leydig cells depend on dose and duration of exposure of the cell to the hormone. Locally produced oestradiol is probably involved in the inhibition of steroidogenesis. (3) The stimulatory action of LH on Leydig cells involves different proteins in concert with the activation of the cleavage activity of mitochondrial cholesterol side-chain. However, most of the functional properties of these proteins are yet unknown. (4) Different populations of Leydig cells are present in the testis. These different cell populations can be characterized by quantitatively and qualitatively different responses to hormones.

Increased testicular 5 alpha-androstane-3 alpha, 17 beta-diol formation induced by treatment with [D-Ser (TBU) 6, des-Gly-NH2(10)] LHRH ethylamide in the rat

While the intact male adult rats respond to LH with a predominant increase of testicular and plasma testosterone levels, the response to LH stimulation in animals treated with the LHRH agonist, [D-Ser(TBU) 6, des-Gly-NH2(10)] LHRH ethylamide is characterized by a major production of 5 alpha-androstane-3 alpha, 17 beta-diol. The marked increase of 5 alpha-androstane-3 alpha, 17 beta-diol levels in the presence of a 90% decrease of testosterone concentration strongly suggests that 5 alpha-reductase and 3 alpha-hydroxysteroid oxidoreductase activities are increased during testicular desensitization induced by treatment with the LHRH agonist.

Simultaneous measurements of testosterone and three 5 alpha-reduced androgens in the venous effluent of immature rat testes in situ

Simultaneous measurements were made by radioimmunoassay of testosterone, 17 beta-hydroxy-5 alpha-androstan-3-one (DHT), 5 alpha-androstane-3 alpha, 17 beta-diol (3 alpha-diol), and 5 alpha-androstane-3 beta, 17 beta-diol (3 beta-diol) in the testicular venous plasma (TVP) and peripheral plasma (PP) of 30, 45, and 55 day old rats. At 30 days of age, the preponderant androgen in both plasmas was 3 alpha-diol but testosterone predominated by day 55. Testosterone levels increased with age in both TVP (6.39, 15.08, and 54.93 ng/ml on days 30, 45, and 55 respectively) and PP (0.13, 0.56, and 1.02 ng/ml on days 30, 45 and 55 respectively) whereas 3 alpha-diol concentrations decreased in TVP (48.07 ng/ml, day 30; 24.85 ng/ml, day 55) though not peripherally (range: 0.41-0.52 ng/ml). DHT was low in both TVP and PP and appeared to rise only slightly although the increase was not statistically significant. Levels of 3 beta-diol remained low and unchanged. These observations suggest that the total androgen content of the venous effluent from the prepubertal rat testis is quite high and that significant changes in peripheral interconversions of androgens are occurring during sexual maturation.

The effects of 5alpha-reduced androgens on maintenance and regeneration of prostate glands and seminal vesicles in castrated and hypophysectomized rats

The effects of 5alpha-androstane-3alpha, 17beta-diol (3alpha-diol) and 5alpha-androstane-3beta, 17beta-diol (3beta-diol) were studied in rats hypophysectomized and treated daily for 30 days with the steroids, starting on the day of surgery (hypophysectomized, H) or 30 days following the removal of pituitary (hypophysectomized regressed, HR). The ability of 3beta-diol to maintain and restimulate the prostate glands and seminal vesicles of castrated (C) and castrated regressed (CR) rats, respectively, was also studied. This androgen (3beta-diol) was able to maintain as well as rejuvenate to some degree the sexual accessory glands of all treatment groups. The prostate glands and seminal vesicles in both castrated experimental groups showed increased stimulation with progressively higher dosages of 3beta-diol. At all dose levels, stimulation of seminal vesicles of CR rats was comparable to that of non-regressed castrates. The prostate glands, on the other hand, showed better maintenance in the higher dosage group. In H rats, the stimulation of sexual accessory glands by both androgens was not significantly different than normal controls. The seminal vesicles and prostate glands of HR rats treated with 3alpha-diol were well stimulated and comparable to those of H rats treated with 3alpha-diol. The seminal vesicles of HR rats treated with 3beta-diol were also well stimulated, though not to the extent as those with 3alpha-diol treatment. The prostate glands of the 3beta-diol treated HR rats were significantly smaller than those of the 3alpha-diol treatment group. However, these miniature glands were morphologically stimulated as evidenced by mitosis of parenchymal cells and accumulation of secretory products in the alveoli. This study clearly indicates that 3beta-diol is biologically active and the degree of stimulation varies with the animal preparation in which the androgens were tested.

The influence of human menopausal gonadotropin, natrium fluoride and cyproterone acetate on the spermatogenesis in immature rats

Human menopausal gonadotropin (HMG), natrium fluoride (NaF) and cyproterone acetate (CYA) were applied to immature male rats between the 26th and 32nd day of life and histological examination was performed in testes of 33rd-day-old rats. HMG treatment alone slightly influenced the spermatid completion process, while NaF evidently increased frequency of occurrence of various seminiferous tubules containing spermatids. CYA alone damaged the spermatid completion process (especially the cap-phase of spermiogenesis), produced a degeneration of meiotic spermatocytes, and decreased the tubular diameter. Those changes were prevented by addition of HMG to the CYA treated animals. The results suggest a possible regulatory role of FSH at the end of the first meiosis, and, also, in the progression of spermiogenesis. The mechanism of action of NaF may be hypothetical, but it probably consists of direct action on the seminiferous epithelium level.

Influence of experimental cryptorchidism on cholesterol side-chain cleavage enzyme and delta5-3beta-hydroxysteroid dehydrogenase activities in rat testes

Testicular cholesterol side-chain cleavage enzyme (CSCCE) and delta5-3beta-hydroxysteroid dehydrogenase (delta5-3beta-HSD) activities were assessed 12 hours and 2, 4, 8, 16, and 32 days after surgical induction of bilateral cryptorchidism in adult rats. Within 12 hours after surgery CSCCE activity (expressed as dpm of isocaproic acid-14C formed from cholesterol-26-14C/3 hours/testis) was significantly reduced (P less than 0.01) in cryptorchid testes to approximately 55% of sham-operated control values and remained depressed at less than 50% of control activities 2, 4, 16, and 32 days after surgery. Cryptorchid testis delta5-3beta-HSD activity (measured by a pregnenolone substrate-depletion assay and expressed as mumoles of products/30 minutes/testis) did not differ from controls (P greater than 0.05) 1/2, 2, or 4 days after translocation of testes to the abdominal cavity. By day 8 of cryptorchidism, however, delta5-3beta-HSD activity was reduced to 60% of control values (P less than 0.05) and continued to decline to approximately 30% of controls during the remainder of the experimental period. These observed alterations in enzyme activities suggest an impairment in the ability of cryptorchid rat testes to synthesize androgens and further indicate that testicular CSCCE is more acutely sensitive to the cryptorchid milieu than delta5-3beta-HSD.

Production and effects of 7 alpha-hydroxytestosterone on testosterone and dihydrotestosterone metabolism in rat testis

1. Testicular 7 alpha-hydroxylation of testerone was assayed in cell extracts of rats between 12 and 79 days of age. Maximal 7 alpha-hydroxylase activity was observed about 60 days, while insignificant activity was obtained prior to 42 days of age. 2. 7 alpha-Hydroxytestosterone, a major metabolite of testosterone in mature rat testis, inhibited 5 alpha-reduction of testosterone in cell extracts of mature but not of immature rat testis. 3. Maximal testicular activity of 3 beta-hydroxysteroid dehydrogenase using dihydrotestosterone as substrate was obtained in the presence of NAD, while maximal 3 alpha-hydroxysteroid dehydrogenase activity was observed with NADP. Both enzyme activites were reversible. 4. Sensitivity toward testosterone inhibition of 3-hydroxysteroid dehydrogenase varied greatly with stage of testis development being highest at 25-27 days of age. In contrast to testosterone, 7 alpha-hydroxytestosterone was an inhibitor of 3 alpha-hydroxysteroid dehydrogenase only. In the mature rat testis 7 alpha-hydroxytestosterone may be a naturally occurring inhibitor of dihydrotestosterone and 5 alpha-androstane-3 alpha, 17 beta-diol formation.

Measurement of androstanediol in plasma in a radioimmunoassay using celite column chromatography

A rapid and relatively simple, but specific, radioimmunoassay for the potent androgen, androstanediol (3 alpha-diol), is described. Despite the availability of a nonspecific C-19 androgen antibody requiring a 17 beta-hydroxy group, androstanediol can be measured in plasma by prior purification of a plasma solvent extract using a Celite microcolumn. Values obtained do not differ from those previously reported using more complicated chromatographic techniques.

Physiological role for androgen binding protein-steroid complex in testis?

The concentration of unbound androgens in the lumen of rat testis seminiferous tubules is not dependent on the presence of the extra-cellular androgen binding protein (ABP); other parameters such as permeability properties, fluid dynamics and metabolic activities in different testicular compartments appear to have a much greater influence. It has been shown that in other target tissues the metabolic effects of steroids on cells depend on the concentration of the steroids which are not bound to extra-cellular proteins. It is therefore unlikely that the physiological function of ABP is related to the accumulation of androgens around germinal cells.

Indices of gonadal function in the human male. II. Seminal plasma levels of steroids in normal and pathological conditions

A radioimmunoassay method developed previously for the measurement of unconjugated pregnenolone, dehydroepiandrosterone, androstenedione, testosterone, dihydrotestosterone and oestradiol in peripheral plasma was applied to the assay of these steroids in seminal plasma of normal, oligospermic and azoospermic males. It was not possible to use the plasma assay method for the determination of progesterone and oestrone in seminal plasma, because some of the reliability criteria were not fulfilled. A detailed analysis of these steroids in the peripheral plasma of the same subjects has been described previously. The levels of all steroids in seminal plasma were significantly lower than the corresponding blood levels. The ratios of blood plasma/seminal plasma levels of the various steroids varied from 37 (testosterone) to 1.7 (dihydrotestosterone). There was a positive correlation between the testosterone and dihydrotestosterone levels of the seminal plasma of normal and azoospermic subjects. The concentrations of dihydrotestosterone, pregnenolone and oestradiol were significantly lower in azoospermic subjects than in normals. The only pathological finding in the seminal plasma of oligospermic subjects was a diminished level of dihydrotestosterone. Enzymic hydrolysis of a seminal plasma pool resulted in a 3- to 8-fold increase in the concentration of pregnenolone, dehydroepiandrosterone, testosterone, dihydrotestosterone and oestradiol, indicating that human seminal plasma contains large amounts of steroid conjugates. It is suggested that the analysis of steroids in the seminal plasma in combination with determinations in peripheral plasma may be a valuable aid to the assessment of testicular function.

3Alpha-androstanediol kinetics in man

Kinetics of 5alpha-androstane-3alpha, 17beta-diol (3alpha-diol) were studied in man. Clearance rates were determined by both the constant infusion and single injection techniques. Production rates were calculated as the product of clearance rate data and plasma values in the a.m. obtained by a radioimmunoassay specific for 3alpha-diol. Mean metabolic clearance rates were 1,776+/-492 (SD) liters/day in males and 1,297+/-219 (SD) liters/day in females. Metabolic clearance rates by single injection were similar. Calculated production rates are 208+/-26 (SD) mug/day in males and 35+/-11 mug/day in females, which are significantly different. Hepatic extraction of 3alpha-diol determined by hepatic vein catheterization during constant infusion was 76% which was greater than expected from information on in vitro binding in plasma. The kinetic data is of interest since 3alpha-diol has a calculated inner pool (V(1)) volume of 12-14 liters, similar to 17beta-hydroxyandrost-4-en-3-one (testosterone) and 5alpha-androstan-17beta-ol-3-one (dihydrotestosterone), but the calculated outer pool (V(2)) of 33.5 liters is very large as are the metabolic rate and transfer constant. In contrast to testosterone and dihydrotestosterone, 3alpha-diol, although bound to sex hormone binding globulin, has a high metabolic clearance of which a large fraction represents extrahepatic (splanchnic) metabolism. A production rate of 3alpha-diol similar to dihydrotestosterone together with rather unique kinetic characteristics encourages further investigation of the biological role of this potent androgen.