Intratesticular steroid levels and their hormonal control

Litter-mate adult male rats were treated with daily intramuscular injections of ACTH (10.5 micrograms), dexamethasone (2.0 mg), ethynyl estradiol (1.7 micrograms) and hCG (5 IU) for three consecutive days. The animals were sacrificed on the fourth day and the intratesticular and peripheral plasma steroid levels were analyzed. The steroids measured by radioimmunoassay included pregnenolone, 17-hydroxypregnenolone, dehydroepiandrosterone, progesterone, 17-hydroxyprogesterone, androstenedione, testosterone and dihydrotestosterone. In addition, the sulphoconjugated forms of pregnenolone, dehydroepiandrosterone, testosterone and dihydrotestosterone were estimated in the peripheral blood. The administration of ACTH diminished the intratesticular levels of all steroids studied. Also dexamethasone and ethynyl estradiol treatment suppressed all intratesticular steroid levels, except that of pregnenolone (the former) and of 17-hydroxyprogesterone (the latter). The suppressive effect of ethynyl estradiol was strongest on the levels of the delta 5-steroids and that of dexamethasone on the delta 4-steroids; the latter was significantly stronger than the effect of ACTH. The stimulatory effect of hCG was limited to the metabolism of progesterone and was restricted to the sequence: 17-hydroxyprogesterone----androstenedione----testosterone---- dihydrotestosterone. Dexamethasone-suppression, and hCG-stimulation of the intratesticular levels of delta 4-steroids, was mirrored by corresponding changes in the peripheral plasma levels, with the exception of the plasma levels of androstenedione which were not influenced by any of the treatments studied. Also the suppression of intratesticular testosterone and dihydrotestosterone levels by ACTH, dexamethasone, or ethynyl estradiol was closely reflected by their plasma levels both in the unconjugated and sulphoconjugated forms. On the hand, the administration of ACTH diminished the intratesticular levels of pregnenolone and progesterone but significantly increased those in the plasma. Moreover, both ACTH and ethynyl estradiol reduced the levels of all delta 5-steroids in testicular tissue, but not in the peripheral plasma, although they decreased the circulating levels of pregnenolone sulphate and dehydroepiandrosterone sulphate. The data are interpreted as suggesting that the hormonal agents studied interfere with testicular steroidogenesis through different mechanisms.     

Progesterone, androstenedione, testosterone, 5 alpha-dihydrotestosterone and androsterone concentrations in specific regions of the human brain

The concentrations of progesterone, androstenedione, testosterone, 5 alpha-dihydrotestosterone and androsterone were determined in tissue samples from the human hypothalamus, anterior pituitary, pineal, amygdala and parietal cortex, taken at autopsy from male (n = 4) and female cadavers (n = 4) of various ages. The measurements were performed using radioimmunoassays for the individual steroids after the chromatographic purification of solvent extracts of tissue samples on Lipidex-5000TM. Preliminary qualitative analyses of the chromatographic profiles of various steroids by radioimmunoassay demonstrated the presence of these steroids in various regions of the brain, but an immunoreactive peak corresponding to 17-hydroxyprogesterone was not found. The concentrations (ng/g tissue wet wt.) of all steroids measured were either very low or below the limit of detection in brain tissues taken from male and female infants. In the adult brain, there was no difference in the distribution of steroids between the various regions studied. There was no sex difference in the brain tissue steroid concentrations, with the exception of testosterone which was clearly much higher in brain tissues from men as compared to women. Although testosterone was undetectable in most samples taken from adult women. 5 alpha-dihydrotestosterone could be measured in almost all samples, which suggests that this is the most important androgen in the human brain. When brain tissue steroid levels are compared with serum concentrations, it can be postulated that a state of equilibrium exists between the fraction of serum steroids which are not bound to high-affinity binding proteins and the amount of steroids in brain tissues.     

Ovine steroid 17alpha-hydroxylase cytochrome P450: characteristics of the hydroxylase and lyase activities of the adrenal cortex enzyme

The steroid 17-hydroxylase cytochrome P450 (CYP17) found in mammalian adrenal and gonadal tissues typically exhibits not only steroid 17-hydroxylase activity but also C-17,20-lyase activity. These two reactions, catalyzed by CYP17, allow for the biosynthesis of the glucocorticoids in the adrenal cortex, as a result of the 17-hydroxylase activity, and for the biosynthesis of androgenic C(19) steroids in the adrenal cortex and gonads as a result of the additional lyase activity. A major difference between species with regard to adrenal steroidogenesis resides in the lyase activity of CYP17 toward the hydroxylated intermediates and in the fact that the secretion of C(19) steroids takes place, in some species, exclusively in the gonads. Ovine CYP17 expressed in HEK 293 cells converts progesterone to 17-hydroxyprogesterone and pregnenolone to dehydroepiandrosterone via 17-hydroxypregnenolone. In ovine adrenal microsomes, minimal if any lyase activity was observed toward either progesterone or pregnenolone. Others have demonstrated the involvement of cytochrome b(5) in the augmentation of CYP17 lyase activity. Although the presence of cytochrome b(5) in ovine adrenocortical microsomes was established, ovine adrenal microsomes did not convert pregnenolone or 17-hydroxypregnenolone to dehydroepiandrosterone. Furthermore the addition of purified ovine cytochrome b(5) to ovine adrenal microsomes did not promote lyase activity. We conclude that, in the ovine adrenal cortex, factors other than cytochrome b(5) influence the lyase activity of ovine CYP17.     

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.     

Formation of neutral steroids from endogenous precursors in minced human fetal adrenals in vitro

The role of endogenous precursors in steroid biosynthesis in the human fetal adrenals was studied in $\text{in vitro}$ incubations with no added exogenous substrate. The identification and quantitative determination of the steroids was carried out by gas-liquid chromatography and gas chromatography - mass spectrometry. During the incubation a 10–60-fold increase in the concentration of dehydroepiandrosterone sulfate was observed. An increase was also seen in the concentrations of the other two steroid sulfates detected, pregnenolone and 17-hydroxypregnenolone sulfate. The concentrations of the corresponding free steroids were seen to decrease during the incubations. Only traces of free dehydroepiandrosterone and progesterone were detected endogenously or at any stage during the incubations. No corticoids could be found. Endogenous cholesterol was found in high concentrations (1.5 – 3.0 mg/g wet tissue) in the tissue samples studied. A small proportion of it was present as a sulfate conjugate.It is concluded that fetal adrenals can form neutral steroid sulfates of the 3β-hydroxy-5-ene series from endogenous precursors $\text{in vitro.}$ Cholesterol which was detected in high concentrations in the adrenal tissue is a possible precursor of these metabolites. The results obtained would suggest that this endogenous metabolism involves sulfated intermediates principally.     

Steroid sulfates in testis tissue of prostatic cancer patients treated for six months with the gonadotropin releasing hormone agonist buserelin

In order to assess the extent of inhibition of testicular steroidogenesis during long-term treatment of prostatic cancer with GnRH agonist, we measured the intratesticular levels of 5 steroid sulfate conjugates in human testis tissue removed from patients after 6 months of intranasal treatment with buserelin. The most pronounced decreases were found in testosterone and pregnenolone sulfates, to 1.6 and 7.1%, respectively, of concentrations measured in testis tissue from primarily orchiectomized prostatic cancer patients. In contrast, clearly smaller decreases were found in three other steroid sulfates measured, those of dehydroepiandrosterone (to 26%), 17-hydroxyprogesterone (to 27%) and 5-androstene-3 beta, 17 beta-diol (to 62%). These results are in keeping with our previous analyses of unconjugated steroids in similar tissue samples, and indicate that testicular steroidogenesis per se is not totally blocked by long-term intranasal treatment with GnRH agonist. Testicular steroid sulfate conjugation may be specifically suppressed since the total concentration of these conjugates decreased more than free steroid levels in our earlier measurements.     

Testicular steroidogenesis in the baboon Papio anubis.

We recently reported that the baboon testis converts pregnenolone to testosterone through the delta-4 pathway. The present studies were to determine the metabolism of intermediates of the delta-4 and delta-5 pathway by the baboon testis. Fragments (50 mg) were incubated for 3 hr with 10 muCi of the following tritium-labelled substrates: pregnenolone, progesterone, 17-hydroxypregnenolone, 17-hydroxyprogesterone, dehydroepiandrosterone, androstenedione, or testosterone. Pregnenolone was converted to testosterone primarily through the delta-4 pathway, with accumulation of progesterone, 17-hydroxyprogesterone and 20alpha-dihydroprogesterone as predominant intermediates. Similar results were obtained in progesterone incubations. 17-hydroxyprogesterone was not efficiently metabolized by the fragments, while 17-hydroxypregnenolone and dehydroepiandrosterone were efficiently converted into testosterone and androstenedione. Androstenedione was metabolized primarily to testosterone, while testosterone was not a suitable substrate. Some 5alpha-androstanediol was identified in each incubate. These results suggest that although testosterone is formed from pregnenolone through the delta-4 pathway, the delta-5 intermediates are more suitable substrates for testosterone synthesis in the baboon testis.     

Effects of chronic ethanol ingestion on steroid profiles in the rat testis

Testosterone, seven of its potential precursors, three of its metabolites and estradiol were analyzed in testes from rats given ethanol for 23 days in a nutritionally adequate liquid diet. The results were compared to those obtained with pair-fed control rats. The concentrations of pregnenolone, progesterone, 17-hydroxyprogesterone, androstenedione and testosterone were markedly lowered in four of the five rats given ethanol. The concentrations of the other 3 beta-hydroxy-delta 5 steroids and estradiol were unchanged, resulting in significantly increased ratios between 17-hydroxypregnenolone and 17-hydroxyprogesterone (P less than 0.025) and between androstenediol and testosterone (P less than 0.025) in the ethanol-treated rats. The results indicate that chronic ethanol administration reduces formation of testosterone by affecting a step prior to pregnenolone. There may also be an effect on the conversion of some 3 beta-hydroxy-delta 5 to the corresponding 3-oxo-delta 4 steroids. The levels of testosterone and three other steroids in testes of rats given the liquid diet were significantly lower than those in testes of animals fed a standard rat chow. This indicates a dietary influence on testicular steroid concentrations.     

Steroid metabolism in human teratocarcinoma cell line PA 1

Human ovarian teratocarcinoma cells of line PA 1, (Zeuthen et al., 1979[1]) used as model for early embryonic cells, were analyzed for their in vitro capacity to convert steroids. The cells were incubated for 20 h with radioactive pregnenolone, progesterone, dehydroepiandrosterone, androstenedione, testosterone or estradiol-17 beta, or with non-radioactive progesterone, 6 alpha- or 6 beta-hydroxyprogesterone, 3 beta-hydroxy-5 alpha-pregnan-20-one, dehydroepiandrosterone or estradiol-17 beta. The metabolites were analyzed by thin layer chromatography or studied by gas chromatography-mass spectrometry. The results indicate that PA 1 cells are able to metabolize, although to a restricted amount, a variety of steroids, most markedly progesterone. The metabolites were almost exclusively found in the medium. The main metabolite of progesterone was 3 beta, 6 alpha-dihydroxy-5 alpha-pregnan-20-one. Minor formation of progesterone from pregnenolone could be detected. Human chorionic gonadotropin did not have any effect on pregnenolone metabolism. No formation of estradiol-17 beta or estrone from dehydroepiandrosterone, androstenedione or testosterone could be detected. However, estradiol-17 beta was shown to be converted mainly to estrone. These findings indicate that undifferentiated PA 1 teratocarcinoma cells like certain mouse teratocarcinoma cells, seem not to be steroidogenic but are capable of metabolizing naturally occurring steroid hormones and their precursors.     

Predominant allylic hydroxylation at carbons 6 and 7 of 4 and 5-ene functionalized steroids by the thermophilic fungus Rhizomucor tauricus IMI23312

This paper demonstrates for the first time transformation of a series of steroids (progesterone, androst-4-en-3,17-dione, testosterone, pregnenolone and dehydroepiandrosterone) by the thermophilic fungus Rhizomucor tauricus. All transformations were found to be oxidative (monohydroxylation and dihydroxylation) with allylic hydroxylation the predominant route of attack functionalizing the steroidal skeleta. Timed experiments demonstrated that dihydroxylation of progesterone, androst-4-en-3,17-dione and pregnenolone all initiated with hydroxylation on ring-B followed by attack on ring-C. Similar patterns of steroidal transformation to those observed with R. tauricus have been observed with some species of thermophilic Bacilli and mesophilic fungi. All metabolites were isolated by column chromatography and were identified by (1)H, (13)C NMR, DEPT analysis and other spectroscopic data. The application of thermophilic fungi to steroid transformation may represent a potentially rich source for the generation of new steroidal compounds as well as for uncovering inter and intraspecies similarities and differences in steroid metabolism.     

Administration of pregnenolone and dehydroepiandrosterone to guinea pigs and rats causes the accumulation of fatty acid esters of pregnenolone and dehydroepiandrosterone in plasma lipoproteins.

Steroids were administered continuously to guinea pigs and rats using subcutaneously applied silastic tubing implants, and the effects on circulating steroid and steroid conjugate levels were monitored. Using implants filled with pregnenolone, we observed that pregnenolone had a marked effect on increasing the levels of its fatty acid-esterified derivative, while dehydroepiandrosterone-releasing implants produced a rise in circulating nonconjugated dehydroepiandrosterone, androst-5-ene-3 beta,17 beta-diol, androstenedione, testosterone, and lipoidal derivatives of both dehydroepiandrosterone and androst-5-ene-3 beta,17 beta-diol. Implants filled with androstenedione produced a 20-fold increase in plasma androstenedione levels relative to untreated controls and a corresponding five-fold increase over control testosterone levels. No fatty acid-esterified derivative of testosterone could be detected within the plasma. Lipoproteins were isolated from both rats and guinea pigs treated with implants filled with pregnenolone or dehydroepiandrosterone. The steroid and steroid fatty acid esters present in each fraction were analyzed, revealing that approximately 75% of all the fatty acid esters of pregnenolone recovered in the lipoproteins was localized within the high-density lipoprotein (HDL) fraction of both guinea pig and rat plasma. Similarly, lipoidal dehydroepiandrosterone was found associated predominantly with the low-density lipoprotein and HDL fractions in the guinea pig, while in the rat this steroid conjugate was exclusively within the HDL fraction. High-density lipoprotein-incorporated tritiated pregnenolone fatty acid esters and dehydroepiandrosterone fatty acid esters were injected into castrated male guinea pigs to study the fate of these complexes.(ABSTRACT TRUNCATED AT 250 WORDS)     

Hormonal steroidogenesis in liver and small intestine of the green frog, Rana esculenta L.

We have investigated the potential of autonomous hormonal steroidogenesis in liver and small intestine of male and female frogs, Rana esculenta, during the recovery phase. After incubation of mitochondrial fractions with [4-14C]cholesterol, female liver and intestine formed pregnenolone at a rate of 0.63 and 2.3 pmol/mg protein/h, respectively, whereas conversion by male organs was only c. 0.03 pmol/mg protein/h. Minced tissues preparations transformed [4-14C]pregnenolone into progesterone and 17alpha-hydroxypregnenolone, the former prevailing in the liver, the latter in the intestine. Moreover, both tissues produced 20alpha-dihydropregnenolone, 20alpha-dihydroprogesterone and dehydroepiandrosterone. From incubates with [4-14C]dehydroepiandrosterone, androstenedione and androst-5-ene-3beta, 17beta-diol were identified, the former being more abundant in the liver, the latter in the intestine. These results indicate that both liver and intestine in frog can be independent sources of hormonally active steroids in both sexes.     

An adrenocortical tumor secreting weak mineralocorticoids

An adrenocortical carcinoma (15.5 g) secreting excessive amounts of steroids with weak mineralocorticoid activity in a 25-year-old woman was studied with particular reference to its in vivo and in vitro secretions of steroids. Severe hypertension, occasional low serum potassium and suppressed PRA were the major clinical findings, and were improved with removal of the tumor. In the preoperative stage, plasma levels of 11-deoxycorticosterone, 18-hydroxy-11-deoxycorticosterone, corticosterone and 18-hydroxycorticosterone were all increased. However, the plasma level of aldosterone was repeatedly normal. Although plasma levels of pregnenolone, 17-hydroxypregnenolone, progesterone and 17-hydroxyprogesterone were very high, those of other late step steroids, i.e. 11-deoxycortisol, cortisol, dehydroepiandrosterone, androstenedione and testosterone were almost normal. From these findings, a major etiological role of weak mineralocorticoids such as 11-deoxycorticosterone, 18-hydroxycorticosterone and corticosterone in her hypertension was suggested. Pregnenolone and 17-hydroxypregnenolone in tumor tissue were increased, but 11-deoxycorticosterone, corticosterone, aldosterone, cortisol and adrenal androgens such as dehydroepiandrosterone, androstenedione and testosterone were below normal or low normal. In vitro production of 11-deoxycorticosterone, aldosterone or cortisol by the tumor tissue slices was very low and scarcely responded to synthetic ACTH.     

Metabolism of pregnenolone by human breast cancer. Evidence for 17 alpha-hydroxylase and 17,20-lyase.

The metabolism of 7-(3)H-pregnenolone was studied in vitro using 16 human breast carcinomas. All mammary tumors transformed pregnenolone to progesterone. All estrogen receptor poor tumors and 4 out of 8 estrogen receptor rich tumors converted pregnenolone to 17-hydroxypregnenolone. Five estrogen receptor poor tumors showed the presence of 17,20-lyase as evidenced by formation of dehydroepiandrosterone and androstenedione. In two estrogen receptor poor tumors, conversions of pregnenolone to progesterone, 17-hydroxy pregnenolone, dehydroepiandrosterone, androstenedione and finally to estradiol was documented, providing a hypothetical pathway for steroid metabolism in human breast cancer. The conversion of pregnenolone to 17-hydroxypregnenolone was significantly less in receptor rich tumors and was totally absent in 4 receptor rich tumors with estrogen receptors of over 45 fmol/mg protein.     

Substrate and nucleotide specificity of placental microsomal 3 beta-hydroxysteroid dehydrogenase

Recent kinetic studies on the placental microsomal 3 beta-hydroxysteroid dehydrogenase have shown that apparent Km values for 3 beta-hydroxy-5-androsten-17-one (dehydroepiandrosterone) and 3 beta-hydroxy-5-pregnen-20-one (pregnenolone) are 15nM and 40nM respectively, which are orders of magnitude lower than found in earlier studies. The purpose of this study was to investigate the substrate and nucleotide specificity of the 3 beta-hydroxysteroid dehydrogenase, and the ability of various steroids to inhibit the reaction at these lower steroid concentrations. Each steroid inhibited the metabolism of the other competitively, and the Ki values obtained were not significantly different from their respective Km values. The ability of various steroids to inhibit the reaction at concentrations of 100nM was usually less than that found at micromolar concentrations. However, certain steroids showed marked inhibition. For example, estrone and estradiol-17 beta inhibit the oxidation of both substrates competitively with Ki values of between 15 and 24nM. The Km values of dehydroepiandrosterone and pregnenolone with NADP+ as cofactor are higher than those with NAD+ as cofactor and the V values are much lower. These data indicate that in human placental microsomes a single 3 beta-hydroxysteroid dehydrogenase, essentially NAD+ specific, metabolizes dehydroepiandrosterone and pregnenolone.     

Neuro-steroids: 3 beta-hydroxy-delta 5-derivatives in rat and monkey brain

The rat brain accumulates pregnenolone (P) as the unconjugated steroid, the sulfate ester (S) and fatty acid esters (L). P + PS do not disappear from rat brain after combined adrenalectomy (adx) and castration (orx). PL does not serve a source of P after adx + orx. P is metabolized by several rat brain regions to progesterone and to PL. Brain microsomes contain the acyl-transferase which converts P to PL using endogenous substrates. Brain P and dehydroepiandrosterone (D) undergo a prominent circadian variation with their acrophases at the beginning of the dark span. The circadian variation of brain D persists after adx + orx. The monkey brain (Macaca fascicularis) also accumulates P and D. Adrenal suppression with dexamethasone for 4 days does not decrease the concentrations of brain P and 3rd ventricle CSFP and D. The concentrations of brain D are decreased to a much smaller extent than plasma D. D inhibits the aggressive behavior of castrated male mice exposed to lactating female intruders. This is not the case for DS or androst-5-ene-3 beta, 17 beta-diol. The D analog 3 beta-methyl-androst-5-en-17-one, which is not estrogenic and cannot be metabolized to testosterone or estradiol, is as active as D in inhibiting the aggressive behavior of castrated mice.     

Developmental changes of serum steroids produced by cytochrome P450c17 in rat

Serum levels of 17-hydroxypregnenolone, dehydroepiandrosterone, 17-hydroxyprogesterone, and androstenedione were measured during the postnatal development of rats 1-14 weeks of age. A significant decrease in the serum levels of these steroids with increasing age was observed, using multiple regression analysis: 17-hydroxypregnenolone (beta= -1.56, S.E.= 0.25, P < 0.00001), dehydroepiandrosterone (beta= -0.43, S.E.= 0.07, P < 0.00001), 17-hydroxyprogesterone (beta= -2.51, S.E.= 0.45, P < 0.00001), and androstenedione (beta= -1.63, S.E.= 0.33, P < 0.00001). A sex-related difference was not found. The observed decline in the serum levels of the steroids was directly proportional to the previously reported decrease in mRNA expression and enzyme activity of cytochrome P450c17 in the rat liver. Yet, despite this decrease to undetectable levels in liver after 7-8 weeks, significant amounts of 17-hydroxypregnenolone, 17-hydroxyprogesterone, dehydroepiandrosterone, and androstenedione were still observed in the rat serum. This may partly be due to the mRNA expression of cytochrome P450c17 in tissues other than the liver, such as the testis and/or duodenum, after 4 weeks of age. Serum levels of pregnenolone, progesterone, and corticosterone in the developing rats were also examined.     

Effect of 3-week treatment with [D-Trp6, des-Gly-NH10(2)]LHRH ethylamide, aminoglutethimide, ketoconazole or flutamide alone or in combination on testicular, serum, adrenal and prostatic steroid levels in the dog

Adult male mongrel dogs were treated with the LHRH agonist [D-Trp6, des-Gly-NH10(2)]LHRH ethylamide, aminoglutethimide, ketoconazole or flutamide alone or in combination for 21 days before measurement of steroid levels in the testes, prostate, adrenals and serum. Ketoconazole alone caused a marked stimulation of the intra-testicular concentration of pregnenolone, 17OH-pregnenolone, progesterone and 17OH-progesterone with no or little change of androstenedione, testosterone and dihydrotestosterone. Aminoglutethimide caused a 30-95% inhibition in the concentration of all steroids in the tests while treatment with the LHRH agonist caused a near complete inhibition of all testicular steroids. When administered concomitantly with the LHRH agonist, ketoconazole partly prevented the inhibitory effect of the LHRH agonist on testicular steroid levels. Serum levels of dehydroepiandrosterone, androst-5-ene-3 beta,17 beta-diol, androstenedione and androstane-3 alpha, 17 beta-diol were 75 to 95% inhibited by the LHRH agonist while serum testosterone and dihydrotestosterone concentrations were reduced below detection limits by the same treatment. Moreover, treatment with the LHRH agonist caused a 70-95% reduction in the intraprostatic concentration of testosterone and dihydrotestosterone in all the groups although maximal effect was observed when the LHRH agonist was combined with any of the three other agents. The present data show that while treatment with ketoconazole, aminoglutethimide or Flutamide alone has only partial inhibitory effects on androgen levels, combination with an LHRH agonist provides maximal inhibition. In addition to its direct blockade of the androgen receptor, some of the effect of Flutamide could be related to its blockade of testicular 3 beta-hydroxy-steroid dehydrogenase activity.     

Pregnenolone and progesterone metabolism by the testes of Bufo arenarum

Sliced testis tissue from Bufo arenarum was incubated in the presence of [³H]pregnenolone. Testis fragments were also used for double isotope experiments using [³H]pregnenolone and [¹⁴C]progesterone. Specific activities were equated with the addition of radioinert pregnenolone. When yields of radiometabolites were analysed, pregnenolone was found to be a good precursor for C₁₉ steroids such as dehydroepiandrosterone, 5-androsten-3β,17β diol, testosterone, 5α-dihydrotestosterone and a C₂₁ steroid, 5α-pregnan-3,20 dione. Progesterone mainly converts to 5α-pregnan-3,20 dione, a steroid with unknown function in amphibians. The 5-ene pathway, including 5-androsten-3β,17β diol as intermediate, could be predominant for androgen biosynthesis. Testes bypass not only progesterone but also androstenedione for testosterone biosynthesis. Accepted: 17 April 1998     

Role of human adipose tissue in the production and metabolism of steroid hormones

Radioimmunological methods have been employed for the simultaneous determination of dehydroepiandrosterone, androstenedione, testosterone, oestrogens (oestradiol + oestrone), progesterone, 17 alpha-hydroxyprogesterone and cortisol in human adipose tissue and peripheral blood to compare the hormone pool of adipose tissue with that in the general circulation. Extremely high steroid concentrations in the adipose tissue and hormone pool in the fat of obese subjects were observed. For adipose tissue/serum steroid ratios, the highest values were obtained for dehydroepiandrosterone and the lowest ones for cortisol. A preliminary study showed a great accumulation of steroids in adjacent adipose tissue of breast tumors. Striking differences were observed in the adipose tissue steroid concentrations between benign and malignant mammary tumors. The present findings revealed that blood hormone determinations may be insufficient to consider the steroid hormone availability in various endocrinopathies or steroid responsive tumors, especially when the endocrine state of extremely obese subjects is observed.