Formation of 5-[17beta-2H]androstene-3beta,17alpha-diol from 3beta-hydroxy-5-[17,21,21,21-2H]pregnen-20-one by the microsomal fraction of boar testis

After incubation of 3beta-hydroxy-5-[17,21,21,21-2H]-pregnen-20-one with the microsomal fraction of boar testis, the metabolites were analyzed by gas chromatography and gas chromatography-mass spectrometry. The following metabolites were identified: 3beta,17alpha-dihydroxy-5-[21,21,21-3H]pregnen-20-one, 3beta-hydroxy-5-androsten-17-one, 5-androstene-3beta,17beta-diol, and 5-[17beta-2H]androstene-3beta,17alpha-diol. The presence of a 2H atom at the 17beta position of 5-androstene-3beta,17alpha-diol was confirmed by oxidizing the steroid with 3beta-hydroxy-steroid dehydrogenase of Pseudomonas testosteroni to obtain 17alpha-hydroxy-4-[2H]androsten-3-one and then by oxidizing the latter steroid with chromic acid to obtain nonlabeled 4-androstene-3,17-dione. Among these metabolites, the first three can be interpreted to be synthesized by a well documented pathway, including 17alpha-hydroxylation followed by side chain cleavage as follows: 3beta-hydroxy-5-[17,21,21,21-2H]pregnen-20-one leads to 3beta,17alpha-dihydroxy-2-[21,21,212H]-pregnen-20-one leads to 3beta-hydroxy-5-androsten-17-one leads to 5-androstene-3beta,17beta-diol. On the other hand, 5-androstene-3beta,17alpha-diol, which contained a 2H atom at the 17beta position, is not likely to be synthesized via above mentioned pathway in which nonlabeled 3beta-hydroxy-5-androsten-17-one is formed as the first C19-steroid. It seems that an alternate side chain cleavage mechanism leading from pregnenolone to 17alpha-hydroxy-C19-steroid exists in boar testis.     

The in vitro metabolism of progesterone, 4-androstene-3,17-dione, testosterone and 17 beta-hydroxy-5 alpha-androstan-3-one by fetal rhesus monkey testes.

Homogenates prepared from fetal rhesus monkey testes were incubated with progesterone, 4-androstene-3,17-dione, testosterone and 17 beta-hydroxy-5 alpha-androstan-3-one. The major progesterone metabolite was 17-hydroxy-4-pregnene-3,20-dione. Testosterone also accumulated in the progesterone incubations. 4-Androstene-3,17-dione was converted chiefly to testosterone. Testosterone was not actively metabolized by the fetal monkey testis. 17 beta-Hydroxy-5 alpha-androstan-3-one was actively converted primarily to 5 alpha-androstane-3 beta,17 beta-diol.     

Gas chromatographic-mass spectrometric study of metabolites of C21 and C19 steroids in neonatal porcine testicular microsomes.

Microsomal fractions obtained from testes of 3-week-old piglets have been incubated, separately, with progesterone, 17-hydroxyprogesterone, 5-pregnene-3 beta,20 beta-diol, 16 alpha-hydroxypregnenolone, 5-androstene-3 beta,17 alpha-diol and dehydro-epiandrosterone. The metabolites, after derivatization, have been separated by capillary gas chromatography and identified by mass spectrometry. Quantification was by selected ion monitoring. Progesterone was shown to be 17-hydroxylated and also converted into 4,16-androstadien-3-one (androstadienone). The major metabolite of 17-hydroxyprogesterone was 4-androstene-3,17-dione (4-androstenedione), but little, if any, androstadienone was formed, indicating that this particular biosynthesis did not require 17-hydroxylation. The metabolites of 5-pregnene-3 beta, 20 beta-diol were found to be 17-hydroxypregnenolone, 3 beta-hydroxy-5,16-pregnadien-20-one (16-dehydropregnenolone) and 5,16-androstadien-3 beta-ol. Dehydroepiandrosterone and 5-androstene-3 beta,17 alpha-diol were interconvertible but neither steroid acted as a substrate for 16-androstene formation. However, dehydroepiandrosterone was metabolized to a small quantity of 4-androstenedione. Under the conditions used, no metabolites of 16 alpha-hydroxypregnenolone could be detected. The present results, together with those obtained earlier, indicate that the neonatal porcine testis has the capacity to synthesize weak androgens, mainly by the 4-en-3-oxo steroid pathway. Although 16-androstenes cannot be formed from C19 steroids, progesterone served as a substrate and may be converted directly to androstadienone, without being 17-hydroxylated first. The pathway to 5,16-androstadien-3 beta-ol, however, involves 17-hydroxypregnenolone and 16-dehydropregnenolone as intermediates.     

In vitro metabolism of 4-androstene-3,17-dione and testosterone by rat submaxillary gland.

Tritiated 4-androstene-3,17-dione and testosterone were incubated with submaxillary gland homogenates of male and female rats. The metabolism was predominately reductive. In 15 and 180 min incubations submaxillary tissue converted 4-androstene-3,17-dione chiefly to androsterone. Less testosterone, 17 beta-hydroxy-5 alpha-androstan-3-one, 5 alpha-androstane-3,17-dione, 5 alpha-androstane-3 alpha, 17 beta-diol, and 4-androstene-3 alpha, 17 beta-diol were also identified. Testosterone was converted to the same products plus 4-androstene-3,17-dione. 5 alpha-Androstane-3 alpha, 17 beta-diol was the major testosterone metabolite. Qualitatively the metabolism by male and female submaxillary gland was similar.     

Analysis of profiles of unconjugated steroids in rat testicular tissue by gas chromatography-mass spectrometry

A gas chromatographic-mass spectrometric (GC-MS) method for analysis of unconjugated steroids in a rat testis is described. A combined solvent-solid extraction procedure, utilizing Lipidex 1000 and Sep-Pak C18, gives a 25-fold purified extract. Steroids in this extract are fractionated by straight phase high-performance liquid chromatography (HPLC) on a LiChrosorb DIOL column in n-hexane-2-propanol, 92:8 (v/v). Four fractions are collected and the steroids are converted to tert-butyldimethylsilyl (TBDMS), 3-enol-TBDMS, and mixed TBDMS-trimethylsilyl (TMS) derivatives using TBDMS- and TMS-imidazole with sodium formate as catalyst under conditions suitable for the steroids present in the respective fractions. The derivatives are purified by reversed phase HPLC in 100% methanol and are analyzed by GC-MS, using selected ion monitoring of the major ions of high mass. For quantification, a mixture of known amounts of ten 14C-labelled steroids, [3H]estradiol and [2H3]estradiol are added to the testis homogenate. The mean concentrations (ng/g wet wt) of the twelve steroids determined were: 4-androstene-3, 17-dione, 4.0; testosterone, 127; 17 beta-hydroxy-5 alpha-androstan-3-one, 4.5; 5 alpha-androstane-3 alpha, 17 beta-diol, 5.7; 5 alpha-androstane-3 beta, 17 beta-diol, 1.5; progesterone, 5.5; 17 alpha-hydroxyprogesterone, 14.4; 3 beta-hydroxy-5-androsten-17-one, 0.07; 5-androstene-3 beta, 17 beta-diol, 0.25; 3 beta-hydroxy-5-pregnen-20-one, 10.3; 3 beta, 17 beta-dihydroxy-5-pregnen-20-one, 0.95; and estradiol, 0.025. Variations between animals were large whereas testes from the same animal in most cases had similar steroid concentrations.     

Formation of 5 alpha-products as major C19-steroids in estrogen-responsive mouse Leydig cell tumor lines

Homogenates of estrogen-responsive mouse Leydig cell tumors (T 124958-R and T 22137) or 28- and 120-day-old mouse testes were incubated with [3H]progesterone or [14C]4-androstene-3,17-dione in the presence of NADPH, and progesterone metabolism and enzyme activities were estimated. The growth of T 124958-R tumor transplanted in BALB/c mice was markedly stimulated by estrogenization of host mice, but the growth of T 22137 tumor was evidently suppressed by the estrogenization. The major C21-17-OH-steroids and C19-steroids formed from progesterone by both tumors and the testes of immature mice were 5 alpha-steroids, such as 3 alpha,17-dihydroxy-5 alpha-pregnan-20-one, 5 alpha-androstane-3,17-dione, androsterone, 3 beta-hydroxy-5 alpha-androstan-17-one and 5 alpha-androstane-3 alpha,17 beta-diol. In contrast, the major steroids formed by the testes of adult mice were testosterone and 4-androstene-3,17-dione, and no or little 5 alpha-steroids were produced. 5 alpha-Reductase activities in both tumor cells (40-50 nmol/l X 10(8) cells per h) were also found to be approx. 5-6 times higher than that in Leydig cells of adult mouse testes (8 nmol/l X 10(8) Leydig cells per h), though 17-hydroxylase activity was much higher in the Leydig cells of adult testes (730 nmol/l X 10(8) Leydig cells per h) than in both tumor cells (1-7 nmol/l X 10(8) cells per h). Furthermore, the presence of significant amounts of endogenous androsterone and/or 5 alpha-androstane-3 alpha,17 beta-diol was demonstrated in both tumors by radioimmunoassay. The present results demonstrate for the first time that C19-5 alpha-steroids are major C19-steroid products (immature type of testicular androgen production) in Leydig cell tumor lines.     

Microbial introduction of a 16 alpha-hydroxyl function into the steroid nucleus.

The introduction of a 16 alpha-hydroxyl function into the steroid nucleus was studied in resting cells of Streptomyces roseochromogenes NRRL B-1233. The oxidation product of dehydroepiandrosterone (DHEA) was identified as 16 alpha-hydroxy DHEA by using thin-layer and gas-liquid chromatography. A linear relation between cell concentration and 16 alpha-OH-DHEA formation was observed. 16 alpha-Hydroxylase showed good activity at pH 8.0 for 16 alpha-OH-DHEA formation. The enzyme showed good activity at 3.1 x 10(-4) M DHEA. The oxidation products of pregnenolone, 4-androstene-3,17-dione, estrone, and 5-androstene-3 beta,17 beta-diol as well as of other substrates were identified as the 16 alpha-hydroxy steroid, respectively. The rates of microbial 16 alpha-hydroxylation were as follows: 76.9% for DHEA, 50.4% for pregnenolone, 43.9% for 4-androstene-3,17-dione, 34.3% for estrone, and 19.6% for 5-androstene-3 beta,17 beta-diol. The organism tested catalyzes 16 alpha-hydroxylation of a wide variety of steroids.     

Metabolism of [4-14C] testosterone in the rat uterus in vitro.

In view of the uterine action of androgens we have investigated in vitro the metabolism of [4-14C]-testosterone in uterine tissue of ovariectomized rats. After purification of the extracts on Amberlite XAD-2 the metabolites have been isolated by gel. Five metabolites were isolated and identified during these incubation studies: 4-androstene 3,17-dione, 17beta-hydroxy-5alpha-androstan-3-one, 5 alpha-androstane-3alpha17beta-diol, 4-androstene-3 beta, 17beta-diol and 4-androstene-3alpha, 17beta-diol. Furthermore, two polar C19O3-metabolites and one isopolar to 5 alpha-androstane-3, 17-dione have also been detected. The metabolites were characterized by radioactive gas chromatogrphy, and determination of the relative specific activity in the eluates of Sephadex column chromatography. The identification of allylic alcohols was complemented by their oxidation to 4-androstene-3,17-dione. The present data show that activity of 17beta,3alpha- and 3beta-hydroxysteroid-oxidoreductase and 5alpha-ring-reductase are involved in the metabolism of testosterone in vitro in the rat uterus. The very low 5 alpha-reductase activity under the experimental conditions used in this work explains the formation of allylalcohols as the principal metabolites of testosterone in the rat uterus.     

Structural requirements for progesterone binding to the hepatic endoplasmic reticulum in the female rat

Microsomes isolated from the liver of the female rat specifically bind progesterone. The progesterone-microsomal complex shows highly specific characteristics. The binding is probably associated with the carbonyl groups at positions C-20 and C-3. Other steroids compete for microsomal binding sites less effectively. Competition for progesterone binding sites by other steroids in percentages: testosterone 33; testosterone propionate, 9; 17-methyltestosterone, 23.2; cortisol, 6.4; estradiol-17 beta, 1.8; 17 alpha-ethynyl estradiol, 4.7; mestranol, 1.0; norethynodrel, 4.5; ethisterone, 7.1; lynestrenol, 4.3; medroxyprogesterone, 23.3; medroxyprogesterone acetate, 15.2; 5 alpha-pregnane-3,20-dione, 47.6; 5 beta-pregnane-3,20-dione, 20.7; pregnenolone, 14.8; 6-methylpregnenolone, 1.2; 16 alpha-methylpregnenolone, 3.8%; 20 beta-hydroxy-4-pregnen-3-one, 2.8; 3 beta-hydroxy-5 alpha-pregnan-20-one, 5.2; 4-pregnene-3 beta, 20 beta-diol, 2.1; 11 alpha-hydroxyprogesterone 21.0; 16 alpha-hydroxyprogesterone, 7.9; 17-hydroxyprogesterone, 26.7; 16 alpha, 17-epoxyprogesterone, 2.7; 16 alpha-methylprogesterone, 3.8; 6-methylpregnenolone, 1.2; 16 alpha-methylpregnenolone, 3.8; promegestone, 27.0. 3 beta-Hydroxy-5 beta-pregnan-20-one, 3 alpha-hydroxy-5 beta-pregnan-20-one, 5-pregnene-3 beta,20 beta-diol, 5-pregnene-3 beta, 20 alpha-diol; 5 alpha-pregnane-3 beta, 20 beta-diol, 5 alpha-pregnane-3 beta, 20 alpha-diol, 5 beta-pregnane-3 alpha, 20 alpha-diol, 5 beta-pregnane-3 alpha, 20 alpha-diol diacetate, 5 beta-pregnane-3 alpha, 20 beta-diol, 3 alpha, 17-dihydroxy-5 beta-pregnan-20-one, 17-hydroxypregnenolone, 6-methyl-17-hydroxypregnenolone, pregnenolone-16 alpha-carbonitrile, dihydrotestosterone and cholesterol show no competition at all. The varying degree of competition by different steroids is unrelated to their lipid solubility.     

Circulating neuroactive C21- and C19-steroids in young men before and after ejaculation

Twelve neuroactive and neuroprotective steroids, androgens and androgen precursors i.e. 3alpha,17beta-dihydroxy-5alpha-androstane, 3alpha-hydroxy-5alpha-androstan-17-one, 3alpha-hydroxy-5beta-androstan-17-one, androst-5-ene-3beta,17beta-diol, 3beta,17alpha-dihydroxy-pregn-5-en-20-one (17alpha-hydroxy-pregnenolone), 3beta-hydroxy-androst-5-en-17-one (dehydroepiandrosterone, DHEA), testosterone, androst-4-ene-3,17-dione (androstenedione), 3alpha-hydroxy-5alpha-pregnan-20-one (allopregnanolone), 3beta-hydroxy-pregn-5-en-20-one (pregnenolone), 7alpha-hydroxy-DHEA, and 7beta-hydroxy-DHEA were measured using the GC-MS system in young men before and after ejaculation provoked by masturbation. The circulating level of 17alpha-hydroxypregnenolone increased significantly, whereas the other circulating steroids were not changed at all. This fact speaks against the hypothesis that a drop in the level of neuroactive steroids, e.g. allopregnanolone may trigger the orgasm-related increase of oxytocin, reported by other authors.     

Synthesis of steroidal lactone by penicillium citreo-viride

The biotransformations of a series of steroids by the fungus penicillium citreo-viride A.C.C.C. 0402 have been investigated, and the conversion to the same product testolactone (1) was observed from progesterone (2), dehydroepiandrosterone (3), 4-androstene-3, 17-dione (4), 5-androstene-3, 17-diol (5) with the exception of pregnenolone (6) and 3beta-hydroxy-5, 16-pregnadien-20-one (7). The possible metabolic pathways of the biotransformations were also discussed in the paper and the fungus penicillium citreo-viride A.C.C.C. 0402 was isolated during screening stains from samples collected from Zhengzhou, Henan province of China.     

Steroid metabolism by purified adult rat leydig cells in primary culture

To characterize Leydig cell steroidogensis, we examined the metabolism of (³H)pregnenolone (3β-hydroxy-5-pregnen-20-one) to androgens in the presence and absence of human chorionic gonadotropin (hCG) as a function of culture duration. Approximately 20–30% of the (³H)pregnenolone was converted to testosterone (17_β-hydroxy-4-androsten-3-one) by purified Leydig cells at 0, 3 and 5 days (d) of culture. Androstenedione (4-androstene-3,17-dione) and dihydrotestosterone (17_β-hydroxy-5_α-androstan-3-one) were also produced while on day 5 of culture, significant amounts of progesterone (4-pregnene-3, 20-dione) were isolated. The Δ⁵ intermediates, 17-hydroxypregnenolone (3β, 17-dihydroxy-5-pregnen-20-one) and dehydroepiandrosterone (3β-hydroxy-5-androsten-17-one), accounted for less than 1% of substrate conversion, indicating a clear preference for Leydig cells to metabolize (³H)pregnenolone via the Δ⁴ pathway. On day 0 of culture, unidentified metabolites consisted of predominately polar steroids while on day 5 of culture, the unidentified metabolites consisted of predominately nonpolar steroids. In the presence of hCG, (³H)pregnenolone metabolism did not differ from basal on day 0 or 3 of culture. HCG increased the conversion of pregnenolone to progesterone and 17-hydroxyprogesterone (17-hydroxy-4-pregnene-3, 20-dione) on 5d. This suggests that Leydig cells cultured for 5d have decreased C_17–20 desmolase activity or that hCG acutely stimulates 3β-hydroxysteroid dehydrogenase and Δ⁴-Δ⁵ isomerase activities.     

Stereospecific removal of the 16 alpha-hydrogen in the biosynthesis of 5,16-androstadien-3 beta-ol from pregnenolone

[16 alpha-2H]Pregnenolone was synthesized by catalytic deuteriation of 3 beta-hydroxy-5,16-pregnadien-20-one followed by base-catalyzed back exchange of the 17 alpha-2H atom, and [16 beta-2H]pregnenolone by catalytic hydrogenation of 3 beta-hydroxy-5,16-[16-2H]pregnadien-20-one, which had been synthesized from [16,16-2H]dehydroepiandrosterone. The labelled pregnenolones were incubated separately with the microsomal fraction of boar testis. The metabolites were analyzed by gas chromatography-mass spectrometry, and the isotope compositions of the following six metabolites were determined: 17-hydroxypregnenolone, dehydroepiandrosterone, 5-androstene-3 beta,17 alpha-diol, 5-androstene-3 beta,17 beta-diol,16 alpha-hydroxypregnenolone and 5,16-androstadien-3 beta-ol. The first four metabolites derived either from [16 alpha-2H]- or from [16 beta-2H]pregnenolone showed essentially the same isotope compositions as those of their respective precursors. The 16 alpha-hydroxypregnenolone and the 5,16-androstadien-3 beta-ol biosynthesized from [16 alpha-2H]pregnenolone lost the 2H label, while the same metabolites biosynthesized from [16 beta-2H]pregnenolone retained the albel. The result shows that the 16 alpha-hydrogen is stereospecifically removed with the retention of the 16 beta-hydrogen in the biosynthesis of 5,16-androstadien-3 beta-ol.     

Progesterone metabolism in the ovaries and testes of the echinoid Lytechinus variegatus Lamarck (Echinodermata)

In the present study we examined the metabolic fate of progesterone (P4) in homogenate and tissue minces of the ovaries and testes of Lytechinus variegatus. P4 was metabolized primarily into 5alpha-reduced metabolites including, 5alpha-pregnane-3,20-dione (DHP), 3beta-hydroxy-5alpha-pregnan-20-one (3beta,20-one), 5alpha-pregnane-3beta,20alpha-diol (3beta,20alpha-diol), 5alpha-pregnane-3beta,20beta-diol (3beta,20beta-diol), and 5alpha-pregnane-3alpha,20alpha-diol (3alpha,20alpha-diol) by both the ovaries and testes. The capacity to metabolize P4 did not differ between the ovaries and testes. However, the relative quantity of Salpha-pregnane-3beta,20zeta-diol synthesized from ovary and testis tissue minces was about 3.3-fold higher than from homogenate preparations. Differences in the synthesis of 3beta,20-one and 3alpha,20alpha-diol in both ovary and testis minces were dependent on reproductive state. This study demonstrates the pathway of P4 conversion in the ovaries and testes of L. variegatus and indicates the rapid conversion of P4 into 5alpha-reduced metabolites in these tissues. Although P4 metabolism is not sex specific, sex-specific responses to P4 metabolites have been demonstrated previously. We hypothesize that the sex-specific responses of the ovaries and the testes to P4 may be associated with receptor-level regulatory processes.     

The biosynthesis of some androst-16-enes from C21 and C19 steroids in boar testicular and adrenal tissue

1. The formation of androst-16-enes from [4-(14)C]progesterone has been investigated with long-term incubations and short-term kinetic studies. After 4hr., 1.7 and 10.3% respectively of 3alpha- and 3beta-hydroxy-5alpha-androst-16-enes were formed in boar testis minces, but much smaller yields were obtained in boar adrenal. Both tissues formed small quantities of androsta-4,16-dien-3-one. 2. The amounts of androst-4-ene-3,17-dione and testosterone isolated were small, suggesting that androst-16-ene formation may occur preferentially in the boar testis. 3. In the absence of tissue no radioactive androst-16-enes were formed. 4. Incubation of both [4-(14)C]pregnenolone and [7alpha-(3)H]progesterone resulted in 3alpha- and 3beta-hydroxy-5alpha-androst-16-enes containing (3)H/(14)C ratios of near unity and confirmed that both C(21) steroids were precursors. A similar incubation with 17alpha-hydroxy[4-(14)C]-progesterone and [7alpha-(3)H]progesterone gave the same Delta(16)-alcohols, but they contained only (3)H, indicating that side-chain cleavage of pregnenolone and progesterone occurred before 17alpha-hydroxylation. 5. Dehydroepiandrosterone, testosterone, testosterone acetate and 16-dehydroprogesterone were not found to be precursors of Delta(16)-steroids. 6. A pathway is proposed for the biosynthesis of 3alpha- and 3beta-hydroxy-5alpha-androst-16-enes from pregnenolone and progesterone; this may involve androsta-4,16-dien-3-one as an intermediate, but excludes 17alpha-hydroxyprogesterone, testosterone and dehydroepiandrosterone.     

Early steroid metabolism in Xenopus laevis, Rana temporaria and Triturus vulgaris embryos.

Embryos of Xenopus laevis, Rana temporaria and Triturus vulgaris exposed to radioactive pregnenolone have been found to convert it to progesterone. Incubations with radioactive progesterone showed that it was actively metabolized by oocytes and embryos. In Xenopus incubations progesterone was converted to 5alpha-pregnane-3,20-dione, 17alpha-hydroxy-4-pregnen-3-one, 4-androstene-3,17-dione and 17alpha-20alpha-dihydroxy-4-pregne-3-one, indicating 5alpha-reductase, 17alpha-hydroxylase, 19-20-desmolase and 20alpha-hydroxylase activities. In oocytes of Triturus and Rana no evidence of 19-20-desmolase was found. In Rana oocytes were also not evidence of 17alpha-hydroxylase activity. All identified activities except 20alpha-hydroxylase were common to embryos of all three species. It is suggested that the steroid enzyme activities present in the embryos are not solely derived from the oocytes but synthentized during early development. Possible meaning of this kind of metabolism during differentiation remains open.     

Progesterone fate in rabbit cornea

Excised cornea from adult New Zealand rabbits were incubated with progesterone-4-14C in Eagle's media for 96 hr. Samples were inactivated at intervals of 24 hr incubation periods. The following metabolites of progesterone were isolated: 20 alpha-Hydroxy-4-pregnen-3-one, 20-hydroxy-4-pregnen-3-one, 5 alpha-pregnane-3,20-dione; 5 beta-pregnane-3,20-dione and 6 beta-hydroxy-4-pregnen-3,20-dione. 20 alpha-Hydroxy-pregnen-3-one was the predominant metabolite of progesterone-4-14C. A linear increase was observed throughout 96 hr. The opposite was found for 5 alpha and 5 beta pregnane-3,20-dione. Compounds remaining at the origin of the paper chromatograms contained 6 beta-hydroxy-4-pregnen-3,20-dione and other still unidentified metabolites of progesterone-4-14C. Presence of 20 alpha and 20 beta-reductase; 5 alpha and 5 beta-reductase and 6 beta-hydroxylase enzyme systems are involved in corneal progesterone metabolism. No fungal neither bacterial enzymatic biotransformation occurred in the culture media.     

Steroid metabolism by rat nasal mucosa: studies on progesterone and testosterone

The metabolism of [4-14C]progesterone and [4-14C]testosterone by slices of the nasal mucosa from rats was studied. As shown by gas chromatography-mass spectrometry there was a preferential formation of reduced progesterone-metabolites (5 alpha-pregnane-3,20-dione, 3 alpha- and 3 beta-hydroxy-5 alpha-pregnane-20-one, 20 alpha- and 20 beta-hydroxypregn-4-en-3-one, 2 alpha,3 alpha-dihydroxy-5 alpha-pregnane-20-one, 3 alpha,16 alpha-dihydroxy-5 alpha-pregnane-20-one) and reduced testosterone-metabolites (4-androstene-3,17-dione, 5 alpha-dihydrotestosterone, 3 alpha-hydroxy-5 alpha-androstane-17-one, and 5 alpha-androstane-3 alpha, 17 beta-diol, 2 alpha-hydroxy-5 alpha-dihydrotestosterone, 5 alpha-androstane-2 alpha,3 alpha, 17 beta-triol) indicating the presence of 5 alpha-reductase, 3 alpha-, 3 beta-, 17 beta-, 20 alpha- and 20 beta-hydroxysteroid oxidoreductase activities in this tissue. Progesterone-metabolites hydroxylated at positions 2 alpha, 6 alpha, 6 beta, 15 alpha and 16 alpha and testosterone-metabolites hydroxylated at positions 1 beta, 2 alpha, 6 beta, 15 beta and 16 alpha were also identified, indicating the presence of several steroid hydroxylases in the nasal mucosa. Autoradiography of the nasal region of rats injected with [4-14C]progesterone or [4-14C]testosterone showed a selective localization of radioactivity in the mucosa covering the olfactory region of the nasal cavity.     

Conversion of testosterone and androstenedione to 5 beta-androstanes by adult male hamster liver cytosol

The incubation of [4-14C]testosterone with adult male hamster liver cytosol at pH 6.7 yielded 5 beta-androstane-3 alpha, 17 beta-diol and small quantities of 5 beta-androstane-3 beta, 17 beta-diol, 17 beta-hydroxy-5 beta-androstan-3-one, 3 alpha-hydroxy-5 beta-androstan-17-one and androstenedione. The use of [4-14C]androstenedione as substrate yielded the same 5 beta-metabolites and also testosterone and a trace of epitestosterone. 5 beta-Androstane-3 alpha, 17 beta-diol was the major metabolite at "low" concentrations of substrate but testosterone and 3 alpha-hydroxy-5 beta-androstan-17-one became the major metabolites as the concentration of the substrate was increased. Small quantities of 5 beta-androstane-3,17-dione and 3 beta-hydroxy-5 beta-androstan-17-one were detected at "high" while 5 beta-androstane-3 alpha, 17 alpha-diol was detected at "low" concentrations of androstenedione. NADPH was more effective than NADH except in the formation of the 3 beta-steroids. Furthermore, the 3 beta-steroids were formed in maximum quantities at a lower pH than the other metabolites. The relative production of the metabolites was consistent with their respective spectrophotometrically determined degree of hydroxyl dehydrogenation.     

Early Steroid Metabolism in Xenopus laevis, Rana temporaria and Triturus vulgaris Embryos

Embryos of Xenopus laevis , Rana temporaria and Triturus vulgaris exposed to radioactive pregnenolone have been found to convert it to progesterone. Incubations with radioactive progesterone showed that it was actively metabolized by oocytes and embryos.
In Xenopus incubations progesterone was converted to 5α-pregnane-3,20-dione, 17α-hydroxy-4pregnen-3-one, 4-androstene-3,17-dione and 17α,20α:-dihydroxy-4-pregnen-3-one, indicating 5α-reductase, 17α-hydroxylase, 19–20-desmolase and 20α-hydroxylase activities. In oocytes of Triturus and Rana no evidence of 19–20-desmolase was found. In Rana oocytes were also not evidence of 17α-hydroxylase activity. All identified activities except 20α-hydroxylase were common to embryos of all three species.
It is suggested that the steroid enzyme activities present in the embryos are not solely derived from the oocytes but synthetized during early development. Possible meaning of this kind of metabolism during differentiation remains open.