Androgen biosynthesis during minipuberty favors the backdoor pathway over the classic pathway: Insights into enzyme activities and steroid fluxes in healthy infants during the first year of life from the urinary steroid metabolome

The steroid profile changes dramatically from prenatal to postnatal life. Recently, a novel backdoor pathway for androgen biosynthesis has been discovered. However, its role remains elusive. Therefore, we investigated androgen production from birth to one year of life with a focus on minipuberty and on production of androgens through the backdoor pathway. Additionally, we assessed the development of the specific steroid enzyme activities in early life. To do so, we collected urine specimens from diapers in 43 healthy newborns (22 females) at 13 time points from birth to one year of age in an ambulatory setting, and performed in house GC-MS steroid profiling for 67 steroid metabolites. Data were analyzed for androgen production through the classic and backdoor pathway and calculations of diagnostic ratios for steroid enzyme activities were performed. Analysis revealed that during minipuberty androgen production is much higher in boys than in girls (e.g. androsterone (An)), originates largely from the testis (An^boys-An^girls), and uses predominantly the alternative backdoor pathway (An/Et; Δ5<Δ4 lyase activity). Modelling of steroid enzyme activities showed age-related effects for 21-, 11-, 17-hydroxylase and P450 oxidoreductase activities as well as 3β-hydroxysteroid dehydrogenase, 11β-hydroxylase type 1/2 and 5α-reductase activities. Sex-related characteristics were found for 21-hydroxylase and 5α-reductase activities. Overall, our study shows that androgen biosynthesis during minipuberty favors the backdoor pathway over the classic pathway. Calculations of specific diagnostic ratios for enzyme activities seem to allow the diagnosis of specific steroid disorders from the urinary steroid metabolome.

Measuring Faecal Epi-Androsterone as an Indicator of Gonadal Activity in Spotted Hyenas (Crocuta crocuta)

Enzyme immunoassays (EIA) that measure faecal testosterone metabolites (fTM) are useful tools to monitor gonadal activity. The aim of this study was to validate an "in-house" epiandrosterone EIA to monitor fTM in spotted hyenas. FTM were characterised in a male and a female hyena that each received an injection of 3H-testosterone. High-performance liquid chromatography (HPLC) analyses revealed a cluster of highly polar enzyme-hydrolysable hormone metabolite conjugates. We performed hydrolysis using β-glucuronidase to deconjugate metabolites and improve sensitivity of the assay. Because β-glucuronidase from Helix pomatia has been reported to bias testosterone measurements in some species, we compared the enzymatic activity of the commonly used β-glucuronidase extracted from H. pomatia with the same enzyme from Escherichia coli. Our results showed that β-glucuronidases from both sources produced similar results from spotted hyena faeces. We therefore hydrolysed samples with H. pomatia enzymes. HPLC analyses also demonstrated that following hydrolysis the epiandrosterone EIA measured significant amounts of immunoreactive metabolites corresponding to radiolabelled metabolites in both sexes. Additionally, HPLC and GC-MS analyses confirmed the presence of epiandrosterone in faeces of spotted hyenas. The biological relevance of the epiandrosterone EIA was validated by demonstrating (1) a significant increase in fTM levels in response to a testosterone injection within 16 h, (2) no biological responsiveness to an adrenocorticotropic hormone (ACTH) injection and (3) significant differences in fTM levels between juvenile males and adult immigrant males in a free-ranging wild population. Our results clearly demonstrate that the epiandrosterone EIA is a reliable non-invasive method to monitor gonadal activity in spotted hyenas.

Identification of a single nucleotide polymorphism in porcine testis cytochrome P450-c17 (CYP17) and its effect on steroidogenesis

Raising uncastrated male pigs could have significant economic benefits for pig production. Uncastrated male pigs can accumulate high levels of 16-androstene steroids, however, resulting in boar taint, which is highly objectionable to consumers. Cytochrome P450-c17 (CYP17) interacts with cytochrome b5 in the biosynthesis of the 16-androstene steroids and the sex steroids from pregnenolone. Amino acid substitutions in CYP17 could therefore affect the ability of this enzyme to catalyze the reactions leading to the production of androstenone and the sex steroids. In this study, we established a sensitive and flexible single-stranded conformational polymorphism technique capable of detecting a single nucleotide polymorphism. We then used this method to identify a substitution from T to A at nucleotide 1317 of CYP17, which caused a change in the amino acid sequence from Leu(439) to His(439). This mutation, however, did not alter the enzyme activity of CYP17 in the biosynthesis of androstenone or sex steroids. Other polymorphisms previously suggested for CYP17, which are vital for the functional interaction of CYP17 with CYB5 in human, were not observed. This study suggests that the synthesis of androstenone in pig testis is not directly affected by any polymorphisms in the coding region of the porcine CYP17 gene.

Development of a cryopreservation protocol for Leydig cells

BACKGROUND

In the present study, we describe a procedure to cryopreserve the postnatal members of the Leydig cell lineage, including progenitor (PLC), immature (ILC) and adult (ALC) Leydig cells from, respectively 21-, 35- and 90-day-old rats.

METHODS

The cells were resuspended in a culture medium supplemented with 1% bovine serum albumin (Dulbecco's Modified Eagle's Medium [DMEM]/F12) to a final concentration of 2 x 10(6)cells/ml and the effects of varying concentrations of dimethylsulfoxide (DMSO) (5, 10, 15 or 20%) were assessed after freezing at -70 degrees C and then storing in liquid nitrogen. After 12 months of frozen storage, these cells were thawed rapidly at 37 degrees C and Trypan Blue exclusion staining and attachment to culture dishes were assessed as measures of viability.

RESULTS

The trypan blue exclusion and attachment rates for Leydig cell stages were around 85% in the presence of 15% DMSO. After frozen storage, Leydig cell steroidogenic capacity in response to a range of LH doses, (0.01-100 ng/ml) was unchanged compared with freshly isolated control cells. Furthermore, the steady-state mRNA levels for Leydig cell specific transcripts were maintained.

CONCLUSIONS

This study demonstrates that purified rat Leydig cells at a range of developmental stages can be frozen and that the cryopreserved cells retain normal function.

17 beta-hydroxysteroid dehydrogenase type XI localizes to human steroidogenic cells

We searched expressed sequence tag databases with conserved domains of the short-chain alcohol dehydrogenase superfamily and identified another isoform of 17 beta-hydroxysteroid dehydrogenase, 17 beta HSDXI. This enzyme converts 5 alpha-androstane-3 alpha, 17 beta-diol to androsterone. The substrate has been implicated in supporting gestation and modulating gamma-aminobutyric acid receptor activity. 17 beta HSDXI is colinear with human retinal short-chain dehydrogenase/reductase retSDR2, a protein with no known biological activity (accession no. AAF06939). Of the proteins with known function, 17 beta HSDXI is most closely related to the retinol-metabolizing enzyme retSDR1, with which it has 30% identity. There is a polymorphic stretch of 15 adenosines in the 5' untranslated region of the cDNA sequence and a silent polymorphism at C719T. A 17 beta HSDXI construct with a stretch of 20 adenosines was found to produce significantly more enzyme activity than constructs containing 15 or less adenosines (43% vs. 26%, P < 0.005). The C719T polymorphism is present in 15% of genomic DNA samples. Northern blot analysis showed high levels of 17 beta HSDXI expression in the pancreas, kidney, liver, lung, adrenal, ovary, and heart. Immunohistochemical staining for 17 beta HSDXI is strong in steroidogenic cells such as syncytiotrophoblasts, sebaceous gland, Leydig cells, and granulosa cells of the dominant follicle and corpus luteum. In the adrenal 17 beta HSDXI, staining colocalized with the distribution of 17 alpha-hydroxylase but was stronger in the mid to outer cortex. 17 beta HSDXI was also found in the fetus and increased after birth. Liver parenchymal cells and epithelium of the endometrium and small intestine also stained. Regulation studies in mouse Y1 cells showed that cAMP down-regulates 17 beta HSDXI enzymatic activity (40% vs. 32%, P < 0.05) and reduces gene expression to undetectable levels. All-trans-retinoic acid did not affect 17 beta HSDXI expression or activity, but addition of the retinoid together with cAMP significantly decreased activity over cAMP alone (32% vs. 23%, P < 0.05). Cloning and sequencing of the 17 beta HSDXI promoter identified the potential nuclear receptor steroidogenic factor-1 half-site TCCAAGGCCGG, and a cluster of three other potential steroidogenic factor-1 half-sites were found in the distal part of intron 1. Collectively, these results suggest a role for 17 beta HSDXI in androgen metabolism during steroidogenesis and a possible role in nonsteroidogenic tissues including paracrine modulation of 5 alpha-androstane-3 alpha, 17 beta-diol levels. 17 beta HSDXI could act by metabolizing compounds that stimulate steroid synthesis and/or by generating metabolites that inhibit it.

Human 17beta-hydroxysteroid dehydrogenase type 5 is inhibited by dietary flavonoids

Phytoestrogens contained in a vegetarian diet are supposed to have beneficial effects on the development and progression of a variety of endocrine-related cancers. We have tested the effect of a variety of dietary phytoestrogens, especially flavonoids, on the activity of human 17beta-hydroxysteroid dehydrogenase type 5 (17beta-HSD 5), a key enzyme in the metabolism of estrogens and androgens. Our studies show that reductive and oxidative activity of the enzyme are inhibited by many compounds, especially zearalenone, coumestrol, quercetin and biochanin A. Among flavones, inhibitor potency is enhanced with increased degree of hydroxylation. The most effective inhibitors seem to bind to the hydrophilic cofactor binding pocket of the enzyme.

Use of bioconversion for the preparation of [4-14C]-labeled 7 alpha- and 7 beta-hydroxylated derivatives of dehydroepiandrosterone and epiandrosterone

The 7 alpha- and 7 beta-hydroxylated derivatives of [4-14C]-dehydroepiandrosterone were prepared with use of the yeast-expressed human cytochrome p4507B1. Epiandrosterone (EPIA), 5 alpha-androstane-3beta,17 beta-diol, and 5 alpha-androstane-3,17-dione were obtained after incubation of [4-14C]-5 alpha-dihydrotestosterone with Escherichia coli-expressed (3beta,17 beta)-hydroxysteroid dehydrogenase from Pseudomonas testosteroni. The 7 alpha- and 7 beta-hydroxylated derivatives of [4-14C]-EPIA produced were prepared after incubation with mycelium of Rhizopus nigricans. Each labeled steroid was purified by chromatography and identified by crystallization to constant specific activity after isotopic dilution with each authentic steroid carrier. Production yields and radio-purity measurements allowed the use of such procedures for the preparation of the described radio-steroids for studies of metabolism and mode of action.

Decrease of core body temperature in mice by dehydroepiandrosterone

Dietary dehydroepiandrosterone (DHEA) reduces food intake in mice, and this response is under genetic control. Moreover, both food restriction and DHEA can prevent or ameliorate certain diseases and mediate other biological effects. Mice fed DHEA (0.45% w/w of food) and mice pair-fed to these mice (food restricted) for 8 weeks were tested for changes in body temperature. DHEA was more efficient than food restriction alone in causing hypothermia. DHEA injected intraperitoneally also induced hypothermia that reached a nadir at 1 to 2 hr, and slowly recovered by 20 to 24 hr. This effect was dose dependent (0.5-50 mg). Each mouse strain tested (four) was susceptible to this effect, suggesting that the genetics differ for induction of hypophagia and induction of hypothermia. Because serotonin and dopamine can regulate (decrease) body temperature, we treated mice with haloperidol (dopamine receptor antagonist), 5,7-dihydroxytryptamine (serotonin production inhibitor), or ritanserin (serotonin receptor antagonist) prior to injection of DHEA. All of these agents increased rather than decreased the hypothermic effects of DHEA. DHEA metabolites that are proximate (5-androstene-3beta, 17beta-diol and androstenedione) or further downstream (estradiol-17beta) were much less effective than DHEA in inducing hypothermia. However, the DHEA analog, 16alpha-chloroepiandrosterone, was as active as DHEA. Thus, DHEA administered parentally seems to act directly on temperature-regulating sites in the body. These results suggest that DHEA induces hypothermia independent of its ability to cause food restriction, to affect serotonin or dopamine functions, or to act via its downstream steroid metabolites.

Hepatocyte growth factor regulates ovarian theca-interstitial cell differentiation and androgen production

During ovarian follicle growth, precise regulation of the onset of androgen production by ovarian theca-interstitial cells (TIC) is necessary for maintaining follicle viability. Thus, temporary suppression of TIC androgen production in preantral follicles is the key to promoting follicle development. Evidence indicates that this process is coordinated via intraovarian growth factors. Hepatocyte growth factor (HGF) can induce granulosa cell (GC) proliferation and suppress follicular atresia, indicating a role for HGF in promoting follicle growth and viability. To determine whether HGF could reversibly suppress androgen production, this study investigated the effect of HGF on TIC differentiation and steroid production. Twenty-six-day-old rats were used in all studies. HGF messenger RNA (mRNA) expression in TIC and GC was determined by reverse transcription-PCR. Agarose gel electrophoresis of the PCR products yielded a single band corresponding to the 290-bp HGF product for both TIC and GC. HGF expression in cultured TIC and GC was not blocked by gonadotropins or HGF. To investigate the effects of HGF on TIC steroidogenesis, TIC were isolated from the ovaries of hypophysectomized rats. TIC (3.0 x 10(4) cells/well) were cultured with LH (0-3 ng/ml) and/or HGF (0-100 ng/ml) for 48 h, and androsterone levels were measured by RIA. HGF did not alter androsterone levels in the absence of LH; however, HGF reversibly impaired LH-dependent androsterone production by as much as 57% (IC50 = 1.5 +/- 0.01 ng/ml). LH (0.3 ng/ml) stimulated progesterone (P4) synthesis by TIC (1201 +/- 190 pg/ml) compared to that by control cells (210 +/- 30 pg/ml). HGF stimulated basal P4 production, and LH-dependent P4 synthesis was augmented 2.6-fold by HGF (ED50 = 0.3 +/- 0.01 ng/ml). The DNA content and cell viability in TIC cultures were not affected by HGF. The effect of HGF on steroidogenic enzyme gene expression in TIC was also investigated via PCR. HGF did not alter the level of basal or LH-induced P450 side-chain cleavage and 3 beta-hydroxysteroid dehydrogenase mRNAs; however, LH-dependent P45017 alpha hydroxylase/C17,20 lyase mRNA content was reduced 4.5 fold in the presence of HGF. Thus, HGF is expressed in both TIC and GC obtained from the immature rat ovary, suggesting its presence in growing follicles. In TIC, HGF stimulated P4 synthesis, but impaired androgen production, concurrent with a down-regulatory effect on P45017 alpha hydroxylase/C17,20 lyase gene expression. Collectively, these results indicate that HGF reversibly impairs LH-stimulated androgen production in TIC. Such effects may help promote folliculogenesis.

Developmental and hormonal regulation of rat theca-cell differentiation factor secretion in ovarian follicles

We have recently presented data demonstrating that preantral follicles secrete a peptide (or family of peptides) that stimulates ovarian theca-interstitial cell (TIC) androgen production by an LH-independent mechanism. The purpose of the study reported here was to study the gonadotropin and developmental regulation of this thecal differentiating factor(s) (TDF) and to determine whether follicle-conditioned medium (FCM) containing TDF bioactivity could stimulate LH receptor and steroidogenic enzyme mRNA expression in TIC. Preantral follicles devoid of theca were obtained by limited enzymatic dispersal of 26-day-old rat ovaries. Follicles were cultured (5 follicles/well) in 96-well plates containing serum-free medium to generate FCM containing bioactive TDF. To bioassay for TDF activity, isolated TIC were cultured (2 days) with 50% FCM; then androsterone production was measured by RIA. Recombinant FSH (rFSH, 0.3-100 mlU/ml) increased TDF bioactivity in a dose-dependent fashion, stimulating maximum androsterone production (20 ng/ml) at 30 mlU/ml. To determine the time course of the production of TDF bioactivity, FCM was collected from follicle cultures treated with and without rFSH at 1, 6, 12, 18, 24, 30, 36, 42, and 48 h. FCM from follicles cultured without rFSH caused a progressive increase in androsterone production to a peak (8 ng/ml) at 18 h followed by a decline to baseline by 48 h. A similar time course was observed for the first 18 h with the rFSH-treated FCM, but androsterone production continued to increase to a level twice that of the untreated FCM (18 ng/ml) at 36 h of culture. In the presence of 100 mlU/ml of rFSH, TDF bioactivity was produced by preantral follicles with > or = 2 layers of granulosa cells but not by small antral follicles, preovulatory follicles, or corpora lutea, demonstrating that production of TDF bioactivity is developmentally regulated. To determine whether FCM could stimulate mRNA expression in TIC, LH receptor, cholesterol side-chain cleavage (P450scc), 3 beta-hydroxysteroid dehydrogenase (3 beta-HSD), and 17 alpha-hydroxylase (P450(17) alpha) mRNAs were measured by reverse transcription polymerase chain reaction assays. FCM stimulated LH-receptor, P450scc, 3 beta-HSD, and P450(17) alpha mRNAs above controls. Our data demonstrate that the production of TDF bioactivity is increased by FSH during a specific stage in follicular development when the theca interna is rapidly differentiating, but its production stops when the follicle develops an antrum. Treatment of TIC with FCM stimulates the expression of the mRNAs coding for LH receptors and the steroidogenic enzymes P450scc, 3 beta-HSD, and P450(17) alpha, mimicking the events that occur during normal thecal differentiation. Thus, it seems likely that TDF is involved in the regulation of initial thecal differentiation in preantral follicles.

Growth hormone stimulates androsterone synthesis by rat theca-interstitial cells

The aim of this study was to assess the possible role of growth hormone (GH) on androsterone synthesis. This effect was analyzed in theca-interstitial cells obtained from immature female rats. The addition of GH to the cultures significantly stimulated androsterone (A) synthesis in a dose- and time-dependent way and this effect was not due to a cellular number increase. When added to the hCG cultures, GH significantly enhanced androgen production even though it did not synergyze with the chorionic gonadotropin. The addition of antibodies anti-IGF-I to the GH cultures did not modify the growth hormone effect suggesting that GH probably does not require IGF-I to achieve its effect on A production. Finally, no effect of GH on cAMP levels were observed in the cultures at the end of the treatment. Our results demonstrate that GH is able to significantly induce A synthesis by rat theca-interstitial cells. Since the presence of GH and its receptors in the ovary is now well established the present data strongly suggest a potential relevance of GH in reproductive biology.

Granulosa cell modulation of luteinizing hormone-dependent androgen production by ovarian theca-interstitial cells: a temporal switch from suppression to augmentation stimulated by follicle-stimulating hormone in vitro

The production of estradiol-17 beta (E2) by granulosa cells (GC) of the dominant follicle is dependent upon LH-stimulated synthesis of androgens by ovarian theca-interstitial cells (TIC). Recent evidence has pointed toward an intrafollicular paracrine system, regulated by FSH and involving GC, that may modulate the LH-dependent production of androgens by TIC. In the present study, the role of GC and FSH in modulating LH-dependent TIC and androsterone production was examined. In cultures of dispersed whole ovarian cells (containing populations of both GC and TIC) from intact immature rats, LH stimulated a 10-fold increase in androsterone production (maximum androsterone = 21.0 +/- 1.1 ng/ml). By comparison, androsterone production was increased 50-fold in LH-stimulated cultures of dispersed whole ovarian cells from hypophysectomized immature rats (108 +/- 18 ng androsterone/ml). The EC50 for LH (0.02 +/- 0.001 ng/ml) was identical in the two cell preparations. We hypothesized that the lesser androgen production by whole ovarian cell cultures from intact rats was due to suppression by the GC. To investigate the role of GC in modulating TIC androgen production, highly purified TIC from immature hypophysectomized rats were cultured in the presence of GC obtained from intact immature rats. Increasing numbers of GC (2.5-100 x 10(3) GC per well) caused a progressive decrease in LH-dependent androsterone production by TIC. Additionally, LH-dependent androsterone production was suppressed by the conditioned medium from recombinant human FSH (rFSH)-stimulated GC (54% of the value for LH-stimulated TIC controls), indicating the involvement of a GC-secreted paracrine factor or factors.(ABSTRACT TRUNCATED AT 250 WORDS)

An autoregulatory process for androgen production in rat thecal-interstitial cells

The regulation of androgen production by thecal-interstitial cells (TIC) of the mammalian ovary is a complex process. Although androgen production is primarily controlled by LH, a variety of factors have been demonstrated to alter LH-stimulated androgen production. It is uncertain, however, if an androgen-mediated autoregulatory process for androgen production exists in TIC. To determine the existence of this phenomenon, TIC obtained from ovaries of immature hypophysectomized rats were enriched by Percoll density gradient centrifugation. When TIC (20,000 viable cells/0.2 ml/well) were cultured for 48 h in the presence of a maximal concentration of hCG (0.2 ng/ml), androsterone production was increased 26-fold versus control levels. Treatment with increasing concentrations (5-1000 nM) of the synthetic androgen 17 beta-hydroxy-7 alpha,17 alpha-dimethyl-4-estren-3-one (mibolerone) inhibited hCG-stimulated androsterone production by an average of 32% at every dose tested. Mibolerone (100 nM) alone was without effect on basal levels of androgens. The addition of insulin (100 ng/ml) or insulin-like growth factor I (100 ng/ml) to TIC cultures did not alter the basal accumulation of androsterone but significantly augmented hCG-induced androgen production by 2- and 3-fold, respectively, versus controls. Concomitant treatment with mibolerone (100 nM) decreased the synergistic action of insulin or IGF-I on hCG-stimulated androsterone synthesis by 46% and 40%, respectively. To elucidate the mechanism(s) of action of mibolerone, we investigated the effects on 8-bromo-cAMP-stimulated androgen production. At a dose of 0.1 mM 8-bromo-cAMP, androsterone production was maximally stimulated to levels observed with 0.2 ng/ml hCG. In the presence of mibolerone (100 nM), cAMP-induced androsterone synthesis was inhibited by 41%. This result suggested that mibolerone was acting at a site distal to cAMP formation. Additional evidence revealed that through the use of the combination of cAMP analogs, N6-monobutyryl-cAMP (50 microM) and 8-bromo-cAMP (75 microM)--which are known activators of the cAMP-dependent protein kinase isoenzymes PKA I and II--androsterone synthesis was increased by 130-fold over basal levels. Treatment with mibolerone (100 nM), however, reduced this cAMP-stimulated androgen synthesis by 51%. Therefore, the results demonstrate the existence of an autoregulatory process for androgen production in TIC, which may be important in limiting the overproduction of androgens.

Transforming growth factor-beta 1 inhibits ovarian androgen production: gene expression, cellular localization, mechanisms(s), and site(s) of action

It is the aim of this study to establish ovarian transforming growth factor-beta 1 (TGF beta 1) gene expression, to reevaluate its cellular localization, and to explore potential interactions of this regulatory peptide on ovarian androgen biosynthesis. Northern analysis of whole ovarian polyadenylated RNA revealed a single 2.5-kilobase transcript corresponding to the TGF beta 1 precursor. Immunohistochemical staining localized the protein to the thecal-interstitial (interfollicular) compartment. To explore potential autocrine effects of TGF beta 1, use was made of whole ovarian dispersates from immature rats the differentiation of which was monitored by the acquisition of androgen biosynthetic capacity. The accumulation of androsterone, the major androgenic steroid detectable in this culture system, increased 5.4-fold over baseline in response to treatment with hCG (1 ng/ml). This effect was further optimized (2- to 4-fold) by supplementation with insulin (1 microgram/ml) and insulin-like growth factor-I (50 ng/ml). In the absence of these optimizing supplements, TGF beta 1 (10 ng/ml) was without effect on basal androsterone accumulation, producing distinct, albeit relatively limited (25%), inhibition of hCG hormonal action. In contrast, supplement-mediated optimization of ovarian androgen biosynthesis revealed TGF beta 1 to be a highly potent inhibitor (greater than 80%) of hCG hormonal action. This reversible TGF beta 1 action proved time and dose dependent, with a minimal time requirement of 72 h and a median inhibitory dose of 2.6 ng/ml. TGF beta 1 action was not due to diminution in the viable cell mass or altered cAMP generation and, therefore, most likely involved a site(s) of action distal to or independent of cAMP generation. Cellular radiolabeling studies of TGF beta 1-treated ovarian cells disclosed the accumulation of steroid intermediates proximal to the 17 alpha-hydroxylation step, suggesting TGF beta 1-mediated blockade at the level of the steroidogenic enzyme 17 alpha-hydroxylase/17-20-lyase. Taken together, these observations are in keeping with the view that TGF beta 1, possibly of thecal-interstitial origin, may not only play a positive paracrine role at the level of the adjacent granulosa cell (as previously reported), but may also constitute one of several autocrine signals concerned with the regulation of ovarian androgen economy. As such, these findings reaffirm the polyfunctional nature of TGF beta 1 action, as manifested by its diametrically opposed effects in different ovarian compartments.

Insulin-like growth factor-I enhances luteinizing hormone binding to rat ovarian theca-interstitial cells

We tested the hypothesis that insulin-like growth factor-I (IGF-I) stimulates ovarian androgen production by increasing theca-interstitial cell luteinizing hormone (LH) binding affinity and/or binding capacity. We then investigated the role of transcriptional and translational events in mediating these actions of IGF-I. LH bound to saturable, high affinity binding sites on rat ovarian theca-interstitial cells. Preincubation with LH produced a decrease in LH binding capacity with no effect on LH binding affinity. Treatment with IGF-I, both in the absence and presence of LH, increased LH binding capacity 1.5- to 2-fold with no change in LH binding affinity. Androgen production was increased progressively by LH, suggesting that LH-stimulated steroidogenesis is not tightly coupled to LH receptor downregulation. IGF-I increased androgen synthesis in proportion to its upregulation of LH binding capacity. Transcriptional inhibition with dichlorobenzimidazole riboside inhibited the IGF-I-mediated increase in LH binding capacity but had no effect on androgen production. Translational inhibition with cycloheximide inhibited both the IGF-I-mediated increase in LH binding and stimulation of androgen synthesis. We conclude that IGF-I increases theca-interstitial cell LH binding capacity and reverses the LH-induced downregulation of LH binding sites. The enhancement of LH binding by IGF-I is compatible with transcriptional mediation whereas the effect of IGF-I on androgen synthesis appears to be mediated by a direct effect of the peptide on the translational process(es) involved in steroidogenesis.

Basic fibroblast growth factor inhibits gonadotropin-supported ovarian androgen biosynthesis: mechanism(s) and site(s) of action

Current evidence favors the hypothesis that granulosa cell-derived basic fibroblast growth factor (bFGF) may be the centerpiece of an intraovarian autocrine loop. In this report we examine the possibility that bFGF may also be involved in paracrine interactions at the level of the ovarian theca-interstitial cell. To this end, whole ovarian dispersates obtained from immature rats were cultured for 96 h under serum-free conditions. The accumulation of androsterone, the major androgenic steroid detected, increased 3- to 5-fold over baseline in response to treatment with hCG (1 ng/ml), an effect further optimized (2- to 4-fold) by supplementation with insulin-like growth factor-I (10 ng/ml), insulin (1 microgram/ml), terbutaline (10(-6) M), or high density lipoprotein (100 micrograms/ml). In the absence of these optimizing supplements, bFGF was without effect on basal androsterone accumulation, but produced a relatively modest (20%) inhibition of hCG hormonal action. In contrast, bFGF proved a highly potent inhibitor (80%) of hCG-stimulated androgen biosynthesis in supplement-enriched cultures. This reversible bFGF action proved to be time and dose dependent, with a minimal time requirement of 48 h and a median inhibitory dose of 2 ng/ml. Unaccounted for by altered (hCG-stimulated) cAMP generation or a diminution in the viable cell mass, the antigonadotropic effect of bFGF may by inference be assumed to involve a site(s) of action distal to or independent of cAMP generation. In this connection, cellular radiolabeling with [3H] pregnanolone (3 alpha-hydroxy-5 alpha-pregnane-20-one) revealed bFGF to be a potent inhibitor of the steroidogenic enzyme 17 alpha-hydroxylase/17-20-lyase. As such, these findings are in keeping with the possibility that locally derived bFGF may exert a dual inhibitory action on (mature) ovarian estrogen production by reducing androgen substrate provision as well as by exercising its now established ability to attenuate granulosa cell aromatase activity.

An improved method for primary culture of ovarian androgen-producing cells in serum-free medium: effect of lipoproteins, insulin, and insulinlike growth factor-I

Although luteinizing hormone (LH) alone stimulates ovarian interstitial cells cultured in serum-free medium to synthesize large amounts of androgens, there seem to be additional factors in vivo that modulate the time course and magnitude of the cellular responses to LH. In an attempt to develop a more nearly physiologic cell culture model, lipoproteins, insulin, and insulinlike growth factor-I (IGF-I) were added to the serum-free medium. The effects of these modifications on androgen biosynthesis by dispersed cells from ovaries of hypophysectomized immature rats cultured in 96-well tissue culture plates were examined. A saturating dose of LH stimulated a 25-fold increase in androsterone synthesis at 2 d, which decreased at 4 and 6 d. Addition of human high density (hHDL) or human low density lipoprotein (hLDL) caused a 2.5-fold increase in LH-stimulated androsterone synthesis. Cells were approximately twice as sensitive to hHDL (ED50 = 5.5 +/- 0.5 micrograms cholesterol/ml) compared to hLDL (ED50 = 9.1 +/- 1.1 micrograms cholesterol/ml). Surprisingly, rat HDL caused only a 40% increase in LH-stimulated androsterone synthesis. When insulin alone was added to cells cultured with a saturating dose of LH, there was a 2.8-fold increase in androsterone synthesis. Addition of hHDL and insulin together caused a synergistic increase in LH-stimulated androsterone synthesis. In contrast to hHDL, which did not change the time course of LH-stimulated androsterone production, insulin prolonged maximal LH-stimulated androsterone synthesis at 4 and 6 d. Inasmuch as the ED50 for insulin action (1.3 +/- 0.1 micrograms/ml) was supraphysiologic, the effects of IGF-I on LH-stimulated androgen synthesis were examined. IGF-I mimicked all of the effects of insulin, but at a physiologic concentration (ED50 = 2.5 +/- 0.3 ng/ml). Ovarian cells cultured in serum-free medium supplemented with hHDL and insulin or IGF-I exhibit responses that closely approximate the physiologic responses observed in vivo. These results suggest that lipoproteins and IGF-I are important physiologic stimulators of ovarian theca-interstitial cell androgen biosynthesis which, when added to the serum-free medium, make the cellular responses in this in vitro model more nearly approximate the responses in vivo.

Insulin-like growth factor I and insulin potentiate luteinizing hormone-induced androgen synthesis by rat ovarian thecal-interstitial cells

We tested the hypothesis that insulin-like growth factor I (IGF-I) and insulin play a role in androgen production by rat ovarian thecal-interstitial cells. Collagenase/DNase-dispersed rat ovarian thecal-interstitial cells obtained from immature hypophysectomized Sprague-Dawley rats were cultured at a concentration of 10(6) cells/ml in serum-free medium in the presence of increasing concentrations of LH, IGF-I, or insulin. The medium was replaced every 48 h, and the androsterone concentration in the culture supernatants was used as an index of androgen production. In the absence of added hormones (control) androsterone levels were consistently less than 0.1 ng/ml. Increasing concentrations of LH stimulated androsterone synthesis in a dose-dependent manner. IGF-I, in the absence of LH, did not significantly increase androsterone levels above control values. However, when combined with 10 ng/ml LH, IGF-I increased androsterone synthesis above levels seen with LH alone in a dose-related fashion: for example, the peak androsterone levels seen with LH and 100 ng/ml (13 nM) IGF-I at 96 h of culture were significantly greater than the peak level seen with 10 ng/ml LH alone (302 +/- 71 vs. 17 +/- 7 ng/ml; P less than 0.0125). Similarly, while insulin alone did not increase androsterone synthesis above control values, androsterone concentrations were increased by insulin in combination with 10 ng/ml LH; a peak value of 240 +/- 67.7 ng/ml was observed at 96 h of culture with 100 ng/ml (18 mM) insulin (P less than 0.025 vs. LH alone) Androsterone levels were slightly less with insulin than with IGF-I, but this difference was not significant. The combination of IGF-I and insulin did not increase levels of androsterone synthesis above those observed with each hormone alone. IGF-I bound to a high affinity binding site on ovarian cell monolayer cultures with an apparent binding affinity of 1.3 x 10(-9) M. Insulin also competed for binding with radiolabeled IGF-I in a dose-dependent manner, but the affinity of insulin was approximately 500-fold less; half-maximal inhibition of [125I] IGF-I binding occurred with an insulin concentration of approximately 300 nM (or approximately 1700 ng/ml). Sodium dodecyl sulfate-polyacrylamide gel electrophoresis of thecal-interstitial cell monolayers affinity labeled with radiolabeled IGF-I in the absence and presence of unlabeled hormone revealed proteins with characteristics of type I IGF receptors. Affinity labeling to a protein of a relative molecular mass of approximately 45,000 was also noted, probably representing IGF carrier proteins synthesized by thecal-interstitial cell monolayers.(ABSTRACT TRUNCATED AT 400 WORDS)

Insulin as a regulator of androgen biosynthesis by cultured rat ovarian cells: cellular mechanism(s) underlying physiological and pharmacological hormonal actions

It is the objective of the in vitro studies reported herein to further evaluate the role of insulin in the regulation of ovarian androgen biosynthesis, to assess its dose requirements, and to elucidate the cellular mechanism(s) underlying its high dose action. To this end, use was made of recently developed primary culture systems of ovarian androgen-producing cells, the differentiation of which is subject to regulation by gonadotropic and insulinotropic signaling. Treatment of collagenase-processed whole ovarian dispersates or highly enriched (greater than 90%) thecal-interstitial cells from immature rats with insulin (1 microgram/ml) or hCG (1 ng/ml), resulted in 1.5- and 2.6-fold increments in the accumulation of androsterone (3 alpha-hydroxy-5 alpha-androstan-17-one), the main androgenic steroid identified in culture medium by HPLC. However, combined treatment with both agents unmasked a synergistic interaction resulting in 5.7-fold amplification of hCG action, the increase in androsterone accumulation representing enhanced biosynthesis rather than diminished degradation. Unaccounted for by cellular growth and independent of the cellular density of plating (1 X 10(4)-1 X 10(6) viable cells/culture) or the hCG dose (0.1-10 ng/ml) employed, the insulin effect proved time and dose dependent with a minimal time requirement of 72 h. [125I-TyrA14]Iodoinsulin binding to untreated highly enriched thecal-interstitial cells proved highly specific, saturable, and reversible, displaying a single class (Hill coefficient = 0.93 +/- 0.07) of high affinity (Kd = 1.7 X 10(-10) M), low capacity (4746 +/- 283 sites/cell) binding sites. Treatment with physiological concentrations (10 ng/ml) of insulin produced limited, albeit measureable, down-regulation of the insulin receptor. In contrast, provision of relatively high concentrations (1 microgram/ml) of insulin resulted (despite marked adsorption/degradation) in substantial (greater than 60%) down-regulation of the insulin receptor, but not the type I insulin-like growth factor receptor, the ligand of which has also been shown to amplify hCG-supported androgen biosynthesis. These findings suggest that the thecal-interstitial cell is a site of insulin reception and action, that physiological concentrations of insulin are capable of participating in the regulation of ovarian androgen biosynthesis, and that this effect is probably mediated via high affinity insulin receptors.(ABSTRACT TRUNCATED AT 400 WORDS)

Conversion of androstenedione to 3 beta-hydroxy-5-androsten-17-one and 3 beta-hydroxy-4-androsten-17-one by the testicular microsomal fraction of Sprague-Dawley rats

When androstenedione was incubated with testicular microsomes of Sprague-Dawley rats in the presence of reduced nicotinamide-adenine dinucleotide (NADH), unknown metabolites were produced, in addition to testosterone and 7 alpha-hydroxyandrostenedione. The metabolites were identified as 3 beta-hydroxy-4-androsten-17-one and 3 beta-hydroxy-5-androsten-17-one (3:1) by biochemical and radiochemical methods. These results confirmed the occurrence of the reverse reactions from androstenedione to 3 beta-hydroxy-4-androsten-17-one and 3 beta-hydroxy-5-androsten-17-one catalyzed by the 3 beta-hydroxysteroid dehydrogenase and 5-ene-4-ene isomerase in the microsomal fraction of Sprague-Dawley rat testes.

Stimulatory effect of prolactin on luteinizing hormone-induced testicular 5 alpha-reductase activity in hypophysectomized adult rats

Two pituitaries from 7-week-old female rats were grafted under the capsule of the left kidney of 50-day-old male rat to induce hyperprolactinemia. All of the pituitary-grafted and sham-operated rats were hypophysectomized at 56 days of age. The hypophysectomized rats in groups of 4 were given daily sc injections of saline or 9 micrograms NIADDK-ovine-(o)LH-23 for 4 and 5 days starting from days 58 and 70, respectively (short and long term hypophysectomized groups). The metabolism of [3H]progesterone or [14C]androstenedione by testicular homogenates, concentrations of testosterone and 5 alpha-androgens (androsterone plus 5 alpha-androstane-3 alpha, 17 beta-diol) in the serum and testes, and testicular LH receptors were estimated. Hypophysectomy caused significant decreases in testicular enzyme activities per gram of tissue, androgen production, and testicular LH receptors. In the testes of hypophysectomized rats, LH treatment significantly stimulated 5 alpha-reductase and 17-hydroxylase activities. Although pituitary grafts alone showed little or no effect on these testicular enzyme activities, hyperprolactinemia induced by the grafts markedly enhanced the LH-stimulated 5 alpha-reductase activity in both groups, especially in the long term hypophysectomized group. Therefore, androsterone and 5 alpha-androstane-3 alpha,17 beta-diol were shown to be the major C19-steroid products (immature type of testicular androgen production) in the LH- and PRL-stimulated testes of long term hypophysectomized adult rats. On the other hand, hyperprolactinemia was associated with a significant inhibition and a slight increase of the LH-stimulated 17-hydroxylase activities in the short and long term hypophysectomized groups, respectively. This difference can be attributed to both a PRL-induced increase in testicular LH receptors and a PRL-induced inhibition of 17-hydroxylase via a postreceptor mechanism(s). The present findings demonstrate for the first time that PRL directly stimulates LH-induced 5 alpha-reductase activity in the testes. It appears that PRL may play a role in the increased production of 5 alpha-C19-steroids and the parallel decrease of testosterone production in immature rat testes.

Concerted metabolism of steroid hormones produced by cocultured ovarian cell types

Ovaries of immature, intact rats were dispersed by collagenase-DNase treatment and cultured in serum-free medium (ovarian cell culture). The hormonal responsiveness of the ovarian cell was compared to that exhibited by pure granulosa cells isolated via needle puncturing. Surprisingly, despite the fact that the majority of the cultured cells should have been comprised of granulosa type, no follicle-stimulating hormone-inducible progesterone or 20 alpha-OH-progesterone (20 alpha-OH-P) could be detected by radioimmunoassay, as typically occurs in cultures of pure granulosa cells. Therefore, in order to unravel the cause for the different responsiveness between the granulosa and the ovarian cell, we applied thin-layer chromatography analysis to follow the metabolic fate of added radioactive pregnenolone to intact monolayers in culture. Such TLC analysis revealed that, after priming with follicle-stimulating hormone, added [3H]pregnenolone was converted to progesterone which was rapidly reduced and finally accumulated as 5 alpha-pregnane-3 alpha,20 alpha-diol(pregnanediol). In addition to pregnanediol, a second class of steroid hormones accumulated in the coculture medium, namely androsterone and 5 alpha-pregnane-3 alpha,17 alpha,20 alpha-triol (pregnanetriol). These latter two were specific products of the ovarian coculture, indicating the presence of theca-interstitial cells bearing 17 alpha-hydroxylase and 17,20-lyase activities. Pregnanediol, rather than progesterone, was found to be the progestin precursor for androgen formation. We thus conclude that due to exchange of steroid metabolites between the cocultured cell types, the final steroid products are different by far from the expected contributions of each individually cultured cell type. Moreover, these findings reveal an additional aspect of the "two-cell theory," suggesting a granulosa-thecal concerted metabolism of progestin steroids, rather than exchange of aromatizable androgens.

Identification of potential antiatherosclerotic/hypolipidemic agents by their effect on hepatic conversion of androst-4-ene-3,17-dione to etiocholanolone and androsterone

Clinical observations have shown that hypercholesterolemia is associated with abnormal androgen metabolism, viz. an increased excretion of etiocholanolone (E) relative to androsterone (A). Substances which restore the A/E ratio to normal likewise lower serum cholesterol. Postulating that the abnormal steroid and sterol metabolism may be either causally related or dependent on the same metabolic defect, we have developed in vitro and in vivo models to select drugs which favorably effect the ratio of A to E produced from [4-14C]androst-4-ene-3,17-dione [4-14C]A-dione). The in vitro model employs a mixture of rat liver microsomal delta 4-3-ketosteroid-5 alpha-reductase and cytosolic 3 alpha-hydroxysteroid dehydrogenase and delta 4-3-ketosteroid-5 beta-reductase. Kinetic and mechanistic studies have been performed on active compounds using this in vitro assay. The in vivo model employs i.v. injection of [4-14C]A-dione followed by collection of bile in anesthetized, hypophysectomized female rats. Many compounds preselected in the in vitro assay likewise reduced the A/E ratio in vivo. One of these compounds (CGS 10614A) also lowered serum cholesterol and reduced the incidence and severity of atherosclerotic lesions in aortas of cholesterol-fed rabbits.

Synthesis of testosterone and 5 alpha-reduced androgens during initiation of spermatogenesis in the rat

Numerous investigators demonstrated increased 5 alpha-reductase activity in testes of developing rats. The rapid in vitro metabolism of progesterone to 5 alpha-reduced androgens occurs at certain stages of testicular development. This was considered evidence for the conclusion that testosterone is primarily an intermediate rather than the final product in testes of immature rats. However, a discrepancy is noted when developmental patterns of circulating or intratesticular levels of androgens are compared with the patterns of accumulation of metabolites of progesterone in vitro. In blood and testicular tissue of 17-20 day old rats a testosterone peak has been reported, while in the in vitro studies such peak was not observed. In this study radiolabelled pregnenolone was utilized in vitro as a substrate, and a pattern of androgen formation similar to that observed in the in vivo studies was noted. A peak of androgen formation (testosterone and 5 alpha-androstanediol) was observed used prior to completion of the meiotic prophase. However, when testosterone was utilized as the substrate, no correlation between 5 alpha-reduction and completion of the meiotic prophase was detected. This suggests that the rise in testosterone may be associated with completion of the meiotic prophase. Investigation of the androgen metabolic pathways revealed the following age-related patterns: no change in 17 beta-hydroxysteroid dehydrogenase, activation of 5 alpha-reductase at 12 days of age, and activation of 3 alpha-hydroxysteroid dehydrogenase between 14 and 18 days of age.(ABSTRACT TRUNCATED AT 250 WORDS)

Direct inhibitory effect of estrogen on LH-stimulated androgen synthesis by ovarian cells cultured in defined medium

The direct inhibitory effect of estrogen on ovarian androgen synthesis was investigated. When primary cultures of rat ovarian theca-interstitial cells were grown in defined medium with LH there was a marked increase in androgen synthesis of which 98% was androsterone (control = 11 +/- 2 ng; LH = 1219 +/- 217 ng/ml/10(6) cells). Diethylstilbestrol (DES), estrone (E1), estradiol (E2), and estriol (E3) inhibited LH-stimulated androsterone synthesis by 81%, 81%, 81%, and 47%, respectively. The ED50's of the estrogens were: DES = 4.2 +/- 2.1 X 10(-9) M; E1 = E2 = 9.5 +/- 2.4 X 10(-8) M; and E3 = 3.8 +/- 2.6 X 10(-7) M. The estrogen effect was very rapid (t1/2 = 10 min) and long-lasting. Metabolic studies revealed that estrogen inhibited androsterone, androstenedione, 5 alpha-androstane-3 alpha, 17 beta-diol, and testosterone accumulation by 80%, dehydroepiandrosterone and 17 alpha-hydroxypregnenolone by 40%, 17 alpha-hydroxyprogesterone by 30%, while pregnenolone and progesterone were unchanged. These results prove, for the first time, that estrogen can directly inhibit LH-stimulated androgen production in ovarian theca-interstitial cells and suggest that mechanism involves, at least in part, a rapid selective inhibition of the 17 alpha-hydroxylase/C17-20 desmolase activities.

Metabolism of testosterone by the epithelium and mesenchyme of the rat urogenital sinus

Testosterone metabolism was measured in separated epithelium and mesenchyme from the urogenital sinuses of 17- and 19-day-old male and female rat embryos and compared with testosterone metabolism in the intact sinus. Both the epithelium and the mesenchyme converted testosterone to 5 alpha-dihydrotestosterone. The epithelium produced much more androstanedione and androsterone but less 3 alpha, 17 beta-androstanediol than did the mesenchyme. The whole sinus synthesized all four metabolites, but in different proportions, producing relatively more androsterone than either of its two component tissues. These data suggest that androsterone is formed by the joint action of epithelium and mesenchyme. Metabolism of testosterone did not differ with sex or foetal age in either of the separated tissues or in the intact sinus, implying that the failure of urogenital mesenchyme from 19-day-old female foetuses to induce prostatic morphogenesis is not due to the loss of 5 alpha-reductase. It is suggested that this lack of inductive capacity may be attributable to a decline in androgen levels with age in female mesenchyme.

[Clinical aspects of the anti-androgens]

The ongoing development and gradual availability of the new anti-androgens hold exciting clinical implications for the future. The biosynthesis and interchangeability of the sex steroids, the roles of the ovaries and adrenals and the value and interpretation of biochemical assays in clinical practice are briefly discussed. Because the anti-androgens are used primarily for seborrhoea/acne/hirsutism/oligomenorrhoea, the pathophysiological basis of this socially debilitating syndrome is discussed. The classification of the anti-androgens, their indications, side-effects, dosage schemes and results of treatment are reviewed. Finally, a summary of a possible clinical management regimen is presented.

Production of testosterone, 5 alpha-androstane-3 alpha, 17 beta-diol and androsterone by dispersed testicular interstitial cells and whole testes in vitro

The production of 5 alpha-androstane-3 alpha, 17 beta-diol (androstanediol), androsterone and testosterone by whole rat testes and testicular interstitial cells dispersed with collagenase was studied in vitro. Luteinizing hormone stimulated the production of each of the androgens by cells prepared from 31- to 34-day-old rats. Half maximum stimulation of the production of each androgen occurred with approximately 3.5 ng NIH-LH-B9/ml medium. Androstanediol was the predominant product then androsterone and then testosterone. Luteinizing hormone stimulated the production of testerone, but not androstanediol or androsterone by dispersed interstitial cells from 200-day-old rats. The time-course of production and the effect of the concentration of cells on the production of these androgens suggested that in dispersed testicular interstitial cells from immature animals androstanediol and androsterone are formed, at least partially, by the metabolism of testosterone. In these experiments LH-stimulated testosterone production increased during incubation for 15--60 min and then remained constant up to 180 min. The concentrations of androstanediol and androsterone increased in a linear manner during incubation for 60--180 min. Varying the number of cells incubated yielded a positive correlation between cell concentration and the ratio 5 alpha-reduced androgen : testosterone produced. Luteinizing hormone stimulated production of each androgen by whole tests obtained from rats at 30--175 days of age. The serum concentration of testosterone in these rats increased abruptly at 50 days of age. Significant changes in androgen production in vitro also observed at this age included: (1) increased production of the three steroids when incubated in either the presence or absence of LH and (2) testosterone production, either in the presence or absence of LH, which represented a greater percentage of the total production of the three androgens.

Formation of 5alpha-reduced C19-steroids from progesterone in vitro by a pathway through 5alpha-reduced C21-steroids in ovaries of late prepubertal rats

Ovarian homogenates from 10-150-day-old rats were incubated with [3H]progesterone and NADPH. Also, ovarian homogenates from 28-day-old rats were incubated for 5-180 min with either [14C]progesterone, [3H]5alpha-pregnane-3,20-dione or [14C]progesterone plus [3H]5alpha-pregnane-3,20-dione. Following incubation, radioactive metabolites were isolated, identified, and measured by column and paper chromatography, with derivative formation and recrystallizations to constant specific activity. Prepubertal ovaries (10, 20, and 28 days of age) converted 15-60% of progesterone to C21-17-hydroxysteroids and C19-steroids. At 40 and 150 days of age (postpubertal), the formation of these steroids decreased to less than 2%. At 10 and 150 days of age, the major C19-steroids formed from progesterone were androstenedione and testosterone. At 20 and 28 days of age, however, no accumulation of these C19-delta4-3ketosteroids was found (less than 0.1% of each), at which time the conversion of progesterone to 5alpha-reduced C19-steriods, such as androsterone and 5alpha-androstane-3alpha,17beta-diol, reached 30%. In ovaries of 28-day-old rats, the results from incubation studies for the detection of metabolic pathways indicated two biosynthetic pathways leading to 5alpha-reduced C19-steroids, one from progesterone via 5alpha-reduced C21 steroids, such as 3alpha-hydroxy-5alpha-pregnan-20-one and 3alpha,17alpha-dihydroxy-5alpha-pregnan-20-one, and a second via 17-hydroxyprogesterone, androstenedione, and testosterone. It seems that the active 5alpha-reduction of C19-delta4-3-ketosteroids and the formation of 5alpha-reduced C19-steroids by the pathway through 5alpha-reduced C21-steroids, are present in the ovaries of older prepubertal rats and may be the biological significance.

In vivo uptake and metabolism of 3-h-5alpha-androstane-3alpha,17beta-diol and of 3-h-5alpha-androstane-3beta,17beta-diol by human prostatic hypertrophy

Tritiated 5alpha-androstane-3alpha,17beta-diol (3alpha-diol) and 5alpha-androstane-3beta,17beta-diol (3beta-diol) respectively were administered to patients with benign prostatic hypertrophy (bph) undergoing prostatectomy. In prostate and skeletal muscle homogenates and in plasma the total radioactivity content as well as the formation of metabolites were measured. Histological examination of each ectomized prostate was performed to evaluate the cellular composition of the tissue. After 3alpha-diol injection, a higher uptake of radioactivity in the prostate was obtained than after 3beta-diol. Within 30 min the 3alpha-isomer was very efficiently converted to 5alpha-DHT, while most of the 3beta-isomer remained unchanged. There was, however, also after administration of the 3beta-diol a substantial biconversion to 5alpha-DHT as has been confirmed by recrystallization to constant specific radioactivity. Only after 3beta-diol epiandrosterone was detected in small but significant amounts. 3alpha-diol administration resulted in distinct concentrations of 3beta-diol, whereas the conversion of 3beta-diol to the 3alpha-isomer was insignificant. When comparing the histological composition of the prostatic tissue with the accumulation of radioactivity and the formation of metabolites only a weak correlation between glandular structure and radioactivity uptake after 3alpha-diol administration could be revealed.

Metabolism of testosterone sulfate in the rat: analysis of biliary metabolites

Following intraperitoneal injection of a mixture of testosterone-7-3-H-17-sulfate and testosterone-4-14-C into male and female rats with bile fistulas, biliary metabolites were separated and purified by a combination of column chromatography, enzymic hydrolysis or solvolysis of the conjugate fractions and identification of the liberated aglycones. The injected steroids were extensively metabolized and excreted predominantly in the bile. The major portion of the 3H was excreted in the disulfate fraction in both sexes. Solvolysis of the disulfate revealed the sex-specific aglycone pattern: 5alpha-Androstane-3beta,17beta-diol was the major metabolite in the male rat, whereas 5alpha-androstane-3alpha,17beta-diol and polar steroids were found in the female. In marked contrast, testosterone was metabolized in a different way than testosterone sulfate. 14-C radioactivity was distributed in monoglucosiduronate, monosulfate, and diconjugate fractions. Analysis of the aglycones showed that polar steroids were the main metabolites in the male. In the female, testosterone was metabolized to polar steroids, androsterone, and 5alpha-androstane-3alpha,17beta-diol.

Testosterone metabolism in cultured hyperplasia of the human prostate

Slices of human benign prostatic hyperplasia were maintained in organ culture in the presence of [3H]- or [14C]testosterone.

Explants concentrated radioactivity from the culture medium, although this effect was depressed by the inclusion of foetal calf serum in the medium.

Testosterone was metabolised to products with chromatographic mobilities corresponding to androstanediols, androsterone, dehydroepiandrosterone, and androstanedione. The principal metabolite was identified as 5α-dihydrotestosterone, and small amounts of testosterone and androstenedione were also found.

As culture time increased from 1 to 6 days there was a diminution in the proportion of 5α-, and an increase in 17-ketometabolites, indicating a swing to a less physiological pattern of testosterone metabolism by the aging culture. Testosterone metabolism was thought to provide a sensitive index by which to evaluate changes in culture conditions.

Metabolism of (7 alpha-3H)dehydroepiandrosterone and (4-14C)androstenedione in vitro by testicular tissue from adult and prepubertal Wistar rats

The metabolism of [7α-3H]dehydroepiandrosterone (DHA) and [4-14C] androstenedione in vitro was investigated in 30-day-old (prepubertal) and adult rat testicular tissue in the presence of cyanoketosteroid, a 5-ene-3β-hydroxysteroid oxidoreductase inhibitor.

Whereas both substrates were converted to 5α-reduced steroids by the prepubertal testis, 4-ene-steroid-5α-reductase activity was negligible in the adult gland. Cyanoketosteroid prevented the formation of 5α-reduced steroids from DHA by the prepubertal testis indicating testosterone and androstenedione as intermediates in their production.

Steroid metabolism by the immature rat testis

Treatment of hypophysectomized immature male rats with luteinizing hormone (LH) greatly increased the metabolism of both 4-[14C]progesterone and 4-[14C]testosterone by testicular homogenates. Prolactin, either alone or in combination with LH, did not influence the metabolism of either substrate. Progesterone was metabolized to 17α-hydroxyprogesterone, androstenedione, 5α-pregnan-3,20-dione, 3α-hydroxy-5α-pregnan-20-one, and 3β-hydroxy-5α-pregnan-20-one. Testosterone was metabolized to dihydrotestosterone and 5α-androstan-3α,17β-diol. On the basis of these observations it is suggested that LH stimulated the 5α-reductase(s) of the immature rat testis. Testis homogenates from immature rats with intact pituitaries were incubated with 4-[14C]3α-hydroxy-5α-pregnan-20-one. Rapid conversion to androsterone was observed, with the formation of a compound chromatographically identical with 3α, 17α-dihydroxy-5α-pregnan-20-one as an apparent intermediate. These findings demonstrate the ability of the rat testes to form androsterone from progesterone by a pathway that does not involve testosterone.

Steroid metabolism by an oestrogen-dependent interstitial-cell tumour of a rat testis

Steroid metabolism by a unique, transplantable, oestrogen-induced, hormone-dependent interstitial-cell tumour of a rat testis was investigated. After incubation of the minced tumour in medium without substrate the presence of 3α-androstanediol, 3-epiandrosterone and androsterone was shown. There was inconclusive evidence for the presence of smaller amounts of 3β-androstanediol, and no evidence for testosterone. [14C]Pregnenolone substrate was shown to be metabolized after 2 h to androstenedione, androsterone and a small amount of testosterone. Epi- and dehydroepiandrosterone were probably formed from [14C]pregnenolone, but were incompletely characterized.