Purification of rat testicular microsomal 17-ketosteroid reductase. Evidence that 17-ketosteroid reductase and 17 beta-hydroxysteroid dehydrogenase are distinct enzymes

Antioxidants (selenium and garlic) alleviated the adverse effects of tramadol on the reproductive system and oxidative stress markers in male rabbits

Tramadol has been used by millions of patients as an analgesic drug to relief the severe pain caused by cancers and other diseases. The current study aimed to investigate the protective effects of antioxidants (garlic and selenium) against the toxic effects of tramadol on semen characteristics, steroid hormones, the protein expressions of different cytochrome P450 isozymes [CYP 21A2, CYP 19, and 11A1], and on antioxidant enzyme activities in testes of rabbits. Western immunoblotting, spectrophotometric, and histological methods were used in this study. Tramadol (1.5 mg/kg body weight) was administered orally to male rabbits for up to three months (three times/week), and after pretreatment of rabbits with garlic (800 mg/kg) and/or selenium (1 mg/kg body weight) by 2 h. The present study showed that motilities, semen volumes, morphologies, sperm counts, testosterone, and estrogen levels were significantly decreased after 4, 8, and 12 weeks of tramadol treatment. In addition, the protein expressions of CYP 21A2, CYP 19, and 11A1 were down-regulated in the testes of the tramadol-treated rabbits. On the other hand, pretreatment of rabbits with garlic, selenium, and/or garlic-selenium for 2 h before administration of tramadol restored the downregulated CYP 21A2 and 11A1 to their normal levels after 12 weeks of tramadol treatment. Activities of antioxidant enzymes including glutathione reductase, glutathione peroxidase, glutathione S-transferase, catalase, superoxide dismutase, and levels of glutathione were inhibited in the testes of tramadol-treated rabbits. On the other hand, free radical levels were significantly increased in the testes of tramadol-treated rabbits for 12 weeks. Interestingly, such changes in the activities of antioxidant enzymes as well as free radical levels caused by tramadol were restored to their normal levels in the rabbits pretreated with either selenium, garlic, and/or their combination. Histopathological investigations showed that tramadol caused substantial vacuolization with the presence of damaged immature spermatozoid in the testes. However, selenium and garlic treatments showed an increase in healthy sperm production with normal mitotic and meiotic divisions. The present study illustrated for the first time the mechanisms of low steroid hormone levels in the testes of tramadol-treated rabbits which could be due to the downregulation of CYPs proteins, induction of oxidative stress, and inhibition of antioxidant enzyme activities. In addition, the present data showed that such toxic effects of tramadol were attenuated and restored to their normal levels after pretreatment of rabbits with garlic, selenium, and/or their combination. This finding may pave the way for a new approach to reducing the toxicity of tramadol.

Vitamin B12 ameliorate Tramadol-induced oxidative stress, endocrine imbalance, apoptosis and NO/iNOS/NF-κB expression in Sprague Dawley rats through regulatory mechanism in the pituitary-gonadal axis

This study aimed at the effect of vitamin B₁₂ (VB₁₂) on tramadol (TRM) induced pituitary-gonadal Axis toxicity. Thirty-two (32) adult male rats were randomized into four groups of eight (n = 8) rats each. Group A served as control was given 1 mL normal saline, group B received 50 mg /kg bwt TRM, group C received 0.5 mg/kg bwt VB₁₂ and group D received 50 mg /kg bwt TRM and 0.5 mg/kg bwt VB₁₂ through gastric gavage daily for 8 weeks. Parameters tested include sperm parameter, male reproductive hormone, testicular histology, glucose, lactate dehydrogenase (LDH), acid phosphate (ACP), and alkaline phosphate (ALP) activity, steroidogenic protein, cytochrome P450 A1, nitric oxide (NO), inducible nitric oxide synthase (iNOS), interleukin-1β (IL-1β), interleukin-6 (IL-6), tumor necrosis factor-α (TNF-α), nuclear factor- kappa B (NF-κB), oxidative and antioxidant makers. Tramadol significantly decreases sperm quality, hormone, steroidogenic protein, cytochrome P450 A1, ACP, ALP, and increases glucose, LDH, oxidative stress, mtTFA, and UCP2, p53 expression, NO, iNOS, NF-κB, IL-1β, IL-6, TNF-α, and caspase-3 activity. Degenerative alterations of the testes' and pituitary architecture and perturbation of spermatogenesis were observed in TRM-treated rats. The intervention of VB₁₂ downregulated testicular oxidative stress, inflammatory markers, glucose, lactate, LDH, p53, caspase-3, mtTFA, and UCP2. And upregulate antioxidant, sperm quality, hormone, and spermatogenic cells. Vitamin B₁₂ exhibited mitigation against TRM-induced testicular dysfunction via its antioxidant, anti-inflammatory and anti-apoptotic effects.

Synergistic effect of curcumin and chitosan nanoparticles on nano-hydroxyapatite-induced reproductive toxicity in rats

Although the toxicity/biocompatibility of hydroxyapatite nanoparticles (HAPNPs), a prospective nano-biomaterial, is extensively studied, its interaction on the reproductive system following exposure is less exploited. In the present study, male rats were exposed to HAPNPs (300 mg/kg BW) to determine its possible reproductive toxicity. Also, the protective effects of chitosan (CSNPs, 280 mg/kg BW) and/or curcumin (CurNPs, 15 mg/kg BW) nanoparticles against HAPNPs-induced reproductive toxicity were studied. Animals were orally gavage daily with respective doses for 45 consecutive days. The obtained results indicated that HAPNPs caused a significant decrease in sperm count, sperm motility, testosterone hormone, steroidogenic enzymes (17-ketosteroid reductase and 17β-hydroxysteroid dehydrogenase), and antioxidant enzymes (glutathione peroxidase, glutathione S-transferase, catalase, and superoxide dismutase) in addition to total antioxidant capacity and reduced glutathione. LH and FSH, abnormal sperm, oxidative stress parameters (thiobarbituric acid-reactive substances (TBARS), nitric oxide (NO), and 8-hydroxy-deoxyguanosine (8-OHdG)), p53, TNFα, and interleukin-6 were significantly increased. The DNA damage was also analyzed by assaying 8-OHdG level which is considered as an indicator of genotoxicity and also suppression of the gene expression of mtTFA, induction of UCP2. Similarly, the histopathological evaluation was also changed following exposure to HAPNPs. The antioxidant activity of CSNPs and CurNPs showed mitigating effect against reproductive deterioration induced by HAPNPs throughout improvements in semen characteristics, sex hormones, inflammatory factors, and antioxidant status. The present study concluded that HAPNPs induced reproductive toxicity and it is important to use nano-antioxidants CSNPs and CurNPs as protective agents.

Production aspects of testosterone by microbial biotransformation and future prospects

In human males, TS plays a key role in maintaining health and sexual functioning. Cholesterol acts as a precursor molecule for its biosynthesis. The microbial biotransformation of cholesterol by numerous microbes like bacteria, fungi, yeasts, etc. has led to the synthesis of TS out of human body making it a great example for industrial steroid production due to its therapeutic properties. Biotransformation through microbes is more advantageous over chemical synthesis as it gives higher conversion rates, higher specificity; reaction goes under mild conditions like temperature and neutral pH, thus being an effective alternate to chemical route. Current review focuses on production aspects of TS by microbial biotransformation and its future prospects with recent advancement.

Erectile dysfunction drugs altered the activities of antioxidant enzymes, oxidative stress and the protein expressions of some cytochrome P450 isozymes involved in the steroidogenesis of steroid hormones

OBJECTIVES

Infertility is a global health problem with about 15 percent of couples involved. About half of the cases of infertility are related to male-related factors. A major cause of infertility in men is oxidative stress, which refers to an imbalance between levels of reactive oxygen species (ROS) and antioxidants. Erectile dysfunction drugs (EDD), known as phosphodiesterase inhibitors (PDEIs), have been used for the treatment of ED. It has been shown that oxidative stress plays an important role in the progression of erectile dysfunction. Oxidative stress can be alleviated or decreased by non-antioxidants and antioxidant enzymes. The present study was undertaken to determine if these compounds could have a role in the incidence of infertility, especially after long-term use. Therefore, the present study aims to investigate the effect of EDD on the activities of antioxidant enzymes, free radical levels as well as the protein expression of different cytochrome P450 isozymes involved in the steroidogenesis of different hormones. In addition, the activity of both 17β-hydroxysteroid dehydrogenase and 17-ketosteroid reductase were assayed. The architectures of both livers and testes cells were investigated under the influence of EDD.

METHODS

A daily dose of Sildenafil (1.48 mg/kg), Tadalafil (0.285 mg/kg) and Vardenafil (0.285 mg/kg) were administered orally to male rabbits for 12 week. Western immunoblotting, ELISA, spectrophotometric and histopathological techniques were used in this study.

RESULTS

The present study showed that Sildenafil, Vardenafil, and Tadalafil treatments significantly decreased the levels of glutathione and free radicals in both livers and testes of rabbits. Also, Vardenafil and Sildenafil induced the activity of superoxide dismutase and catalase whereas, glutathione S-transferase, glutathione reductase, and glutathione peroxidase activities inhibited in livers of rabbits. The protein expression of cytochrome P450 isozymes (CYP 11A1, 21A2, and 19C) which are involved in the steroidogenesis was markedly changed in both livers and testes of rabbits after their treatments for 12 weeks. After the treatment of rabbits with these medication, the protein expression of CYP11A1 was slightly down-regulated in both livers and testes except Sildenafil up-regulated such protein expression. In addition, the protein expressions of CYP11A1 and CYP 19C in both livers and testes were down-regulated after treatment of rabbits with Sildenafil, Vardenafil, and Tadalafil for 12 weeks. Also, these drugs inhibited the activity of both 17β-hydroxysteroid dehydrogenase and 17-ketosteroid reductase in testes of rabbits. Moreover, Sildenafil, Vardenafil, and Tadalafil-treated rabbits showed a decrease in spermatocytes and the number of sperms in the testes.

CONCLUSIONS

It is concluded that ED drugs induced the activities of both SOD and catalase which consequently decreased MDA level. Decrement in MDA levels and oxidative stress could therefore sustain the erection for a long period of time. On the other hand, it is not advised to use these drugs for a long-term since the protein expressions of CYP isozymes involved in steroidogenesis as well as the numbers of spermatocytes in testes were decreased.

The impact of a standardized micronutrient supplementation on PCOS-typical parameters: a randomized controlled trial

PURPOSE

To evaluate whether a micronutrient supplementation preparation that includes a high amount of omega-3 unsaturated acids, other anti-oxidants and co-enzyme Q10 would have an impact on specific serum parameters in women with polycystic ovary syndrome (PCOS).

METHODS

The study was designed as a monocentral, randomized, controlled, double-blinded trial, from June 2017 to March 2018 (Clinical Trials ID: NCT03306745). Sixty women with PCOS were assigned to either the "multinutrient supplementation group" (one unlabeled soft capsule containing omega-3 fatty acids and one unlabeled tablet containing folic acid, selenium, vitamin E, catechin, glycyrrhizin, and co-enzyme Q10, for 3 months) or the "control group" (two unlabeled soft capsules containing 200 μg folic acid each, for 3 months). The main outcome parameters were anti-Mullerian hormone (AMH), total testosterone, and androstenedione. In addition, the focus was on luteinizing hormone (LH), follicle-stimulating hormone (FSH), the LH:FSH ratio, sexual hormone-binding globulin (SHBG), and estradiol.

RESULTS

In the multinutrient supplementation group, the LH:FSH ratio (2.5 ± 1.1 versus 1.9 ± 0.5, p = 0.001), testosterone (0.50 ± 0.19 versus 0.43 ± 0.15, p = 0.001), and AMH (8.2 ± 4.2 versus 7.3 ± 3.6, p < 0.001) declined significantly, whereas the other parameters, namely estradiol, LH, FSH, androstenedione, and SHBG remained stable.

CONCLUSION

A micronutrient supplementation that includes omega-3 fatty acids, folic acid, selenium, vitamin E, catechin, glycyrrhizin, and co-enzyme Q10, given for a minimum of 3 months, is beneficial for women with PCOS in terms of PCOS-specific parameters (LH:FSH ratio, serum testosterone and serum AMH).

Metabolic engineering of Rhodococcus ruber Chol-4: A cell factory for testosterone production

Rhodococcus ruber Chol-4 is a potent steroid degrader that has a great potential as a biotechnological tool. As proof of concept, this work presents testosterone production from 4-androstene-3,17-dione by tailoring innate catabolic enzymes of the steroid catabolism inside the strain. A R. ruber quadruple mutant was constructed in order to avoid the breakage of the steroid nucleus. At the same time, an inducible expression vector for this strain was developed. The 17-ketoreductase gene from the fungus Cochliobolus lunatus was cloned and overexpressed in this vector. The engineered strain was able to produce testosterone from 4-androstene-3,17-dione using glucose for cofactor regeneration with a molar conversion of 61%. It is important to note that 91% of the testosterone was secreted outside the cell after 3 days of cell biotransformation. The results support the idea that Rhodococcus ruber Chol-4 can be metabolically engineered and can be used for the production of steroid intermediates.

Engineering Mycobacterium smegmatis for testosterone production

A new biotechnological process for the production of testosterone (TS) has been developed to turn the model strain Mycobacterium smegmatis suitable for TS production to compete with the current chemical synthesis procedures. We have cloned and overexpressed two genes encoding microbial 17β‐hydroxysteroid: NADP 17‐oxidoreductase, from the bacterium Comamonas testosteroni and from the fungus Cochliobolus lunatus. The host strains were M. smegmatis wild type and a genetic engineered androst‐4‐ene‐3,17‐dione (AD) producing mutant. The performances of the four recombinant bacterial strains have been tested both in growing and resting‐cell conditions using natural sterols and AD as substrates respectively. These strains were able to produce TS from sterols or AD with high yields. This work represents a proof of concept of the possibilities that offers this model bacterium for the production of pharmaceutical steroids using metabolic engineering approaches.

Effects of benzo[a]pyrene as an environmental pollutant and two natural antioxidants on biomarkers of reproductive dysfunction in male rats

Benzo[a]pyrene (B[a]P) is an environmental toxicant and endocrine disruptor. Therefore, the aim of the present study was to investigate the toxicity of B[a]P in testis of rats and also to study the role of silymarin and thymoquinone (TQ) as natural antioxidants in the alleviation of such toxicity. Data of the present study showed that levels of testosterone, estrogen and progesterone were significantly decreased after treatment of rats with B[a]P. In addition, B[a]P caused downregulation of the expressions of steroidogenic enzymes including CYP17A1 and CP19A1, and decreased the activity of 17-β hydroxysteroid dehydrogenase (17β-HSD). Moreover, B[a]P decreased the activities of antioxidant enzymes including catalase (CAT), glutathione peroxidase (GPX) and superoxide dismutase (SOD), and significantly increased free radicals levels in testis of male rats. However, pretreatment of rats with silymarin prior to administration of B[a]P was found to restore the level of free radicals, antioxidant status, and activities of steroidogenic enzymes to their normal levels in testicular tissues. Moreover, histopathological finding showed that silymarin recovered the abnormalities occurred in tubules caused by B[a] P in testis of rats. On the other hand, TQ showed pro-oxidant effects and did not ameliorate the toxic effects of B[a] P on the testicular tissue since it decreased antioxidant enzymes activities and inhibited the protein expression of CYP11A1 and CYP21A2 compared to control rats. Moreover, TQ decreased the levels of testosterone, estrogen, and progesterone either in the presence or absence of B[a]P. It is concluded that B[a]P decreased testosterone levels, inhibited antioxidant enzymes activities, caused downregulation of CYP isozymes involved in steroidogenesis, and increased free radical levels in testis. Moreover, silymarin was more effective than TQ in restoring organism health and alleviating the deleterious effects caused by B[a]P in the testis of rats. Due to its negative impact, it is highly recommended to limit the use of TQ as a dietary supplement since millions of people in the Middle East are using it to improve their health.

Protective role of Nigella sativa oil against reproductive toxicity, hormonal alterations, and oxidative damage induced by chlorpyrifos in male rats

This study is aimed at elucidating the possible protective effects of Nigella sativa oil (NSO) in alleviating the toxicity of chlorpyrifos (CPF) on reproductive performance in male rats. Animals were orally administered with NSO (1 ml/kg/day), CPF (20 mg/kg/day), and NSO + CPF every day for 4 weeks. Results showed that CPF decreased spermatid number, sperm count, daily sperm production, and sperm motility while increased dead sperm and abnormal sperm compared with the control. Also the levels of testosterone, thyroxine levels, steroidogenic enzyme 17-ketosteroid reductase, body weight, food intake, and relative weight of reproductive organs were decreased. Thiobarbituric acid reactive substances were increased, while glutathione (GSH) and antioxidant enzymes were decreased in plasma and testes of rats treated with CPF. Histopathological examination of testes showed a decrease in the number of seminiferous tubules, form shrinkage, enlargement of the connective tissue and gametogenic changes in germ cells of rats treated with CPF. NSO alone increased testosterone, semen characteristics, GSH, and antioxidant enzymes and decreased the levels of free radicals. Furthermore, the presence of NSO with CPF alleviates its toxic effects. Our results indicated that NSO can improve semen picture and moderate CPF-induced reproductive toxicity.

Protective role of L-carnitine and vitamin E on the testis of atherosclerotic rats

Atherosclerosis is a condition caused by lipid build-up and inflammation in the arteries, so hyperlipidemia is the major reason for atherosclerosis. Testis was found to be negatively affected by hyperlipidemia which leads to its impaired functions. Vitamin E and l-carnitine have well-known lipid-lowering and antioxidative activities. Triton WR 1339 is a non-ionic detergent, which induces severe hyperlipidemia by inhibition of lipoprotein lipase. The present study evaluates the protective role of vitamin E and l-carnitine on the testis in atherosclerosis and detects the most effective choice for protection against atherosclerosis; vitamin E, l-carnitine or a combination of both. A total of 80 albino male rats were divided into eight groups (10 rats for each group): control (G1), triton (G2), l-carnitine (G3), triton + l-carnitine (G4), vitamin E (G5), triton + vitamin E (G6), l-carnitine + vitamin E (G7) and triton + l-carnitine + vitamin E (G8). Data showed a significant increase in the levels of total cholesterol (TC), triglycerides (TGs), low-density lipoprotein cholesterol (LDL-C), 17 beta hydroxysteroid dehydrogenase (17 β HSD), testicular catalase and malondialdehyde (MDA) in G2 when compared with G1, whereas high-density lipoprotein cholesterol (HDL-C), serum testosterone, testicular 17 ketosteroid reductase (17 KSR), total thiol and glutathione- S-transferase (GST) data showed a significant decrease in G2 when compared with G1. Treatment with l-carnitine or/and vitamin E helps in improving the adverse effect of triton; also the histological changes confirm this finding. So the present study recommends all people to include l-carnitine and vitamin E in their diet to be protected against atherosclerosis.

Testosterone, androstenedione, and 5alpha-dihydrotestosterone on male sexual behavior and penile spines in the hamster

The expression of masculine sexual behavior (MSB) in male hamsters is optimally stimulated by aromatizable androgens like androstenedione (AD) and testosterone (T), while the non-aromatizable androgen, 5alpha-dihydrotestosterone (DHT), exerting potent androgenic peripheral effects, only in high doses maintains MSB after castration. No data exist on the ability of these androgens to restore long intromissions after castration. In this study, AD, T, and DHT were administered to four-week gonadectomized, sexually experienced male hamsters, for three weeks, in doses of 25 microg/day or up to 1000 microg/day to compare their potency in restoring MSB, penile size, and penile spines growth. Plasma levels of these steroids and the metabolites estrone and estradiol, were determined at the end of the treatment period. Gonadectomy completely suppressed MSB and induced a regression of penile spines. AD was more potent than T in restoring MSB, ejaculatory behavior being displayed by most castrated subjects with a lower dose of AD (50 microg/day) than of T (300 microg/day), and long intromissions being shown by all AD-treated castrated hamsters but only by 20% of T-treated ones, when doses of 1000 microg/day were given. DHT did not stimulate any copulatory response. The three androgens, even at the lowest dose, partially stimulated penis and penile epithelium growth, DHT showing the highest potency. Treatment of castrated hamsters with AD (50 microg/day), restored steroid levels to similar values as those of intact animals. These results show that AD and T restored MSB even with a partial stimulation of penile spines growth, AD being more potent than T. In contrast, DHT did not restore MSB in the hamster in spite of its peripheral androgenic potency.

Effects of hormonal replacement with androgens and estrogens on male sexual behavior and plasma levels of these steroids in gonadectomized golden hamsters (Mesocricetus auratus)

Because the endocrine control of sexual behavior in male hamsters remains controversial, this study analyzed the influence of different androgens and estrogens in the regulation of masculine, sexual behavior (MBS). Aromatizable androgens: androstenedione (A) and testosterone (T), a non-aromatizable androgen: 5alpha-dihydrotestosterone (DHT), as well as estrogens (E2 and E1) alone or in combination with DHT, were administered in gonadectomized, sexually experienced males, for 3 weeks. In addition, plasma levels of these steroids were determined. Gonadectomy completely suppressed masculine sexual behavior (MSB) after 4 weeks. Both A and T replacements restored all the sexual behavior parameters in castrated hamsters by the 3rd week of treatment, with A being more potent in restoring all copulatory series and maintaining all MSB parameters, including long intromissions. Castrated males treated with DHT showed little interest in the female and did not display any copulatory behavior. Gonadectomized males treated with estrogens alone showed active anogenital investigation and displayed some mounts, but did not ejaculate. Males treated with estrogens combined with DHT had longer latencies and less number of ejaculations than males treated with aromatizable androgens. Long intromissions were observed only in males treated with T or A. Plasma levels of A were significantly higher than T levels in intact males. In males treated with A both androgens and estrogens were present in plasma. These results support the notion that aromatizable androgens, mainly A, but not non-aromatizable androgens or even estrogens in combination with DHT, play a relevant role in the endocrine regulation of MSB in the golden hamster.

Altered testicular microsomal steroidogenic enzyme activities in rats with lifetime exposure to soy isoflavones

Androgen production in the testis is carried out by the Leydig cells, which convert cholesterol into androgens. Previously, isoflavones have been shown to affect serum androgen levels and steroidogenic enzyme activities. In this study, the effects of lifelong exposure to dietary soy isoflavones on testicular microsomal steroidogenic enzyme activities were examined in the rat. F1 male rats were obtained from a multi-generational study where the parental generation was fed diets containing alcohol-washed soy protein supplemented with increasing amounts of Novasoy, a commercially available isoflavone supplement. A control group was maintained on a soy-free casein protein-based diet (AIN93G). The diets were designed to approximate human consumption levels and ranged from 0 to 1046.6 mg isoflavones/kg pelleted feed, encompassing exposures representative of North American and Asian diets as well as infant fed soy-based formula. Activities of testicular 3beta-hydroxysteroid dehydrogenase (3beta-HSD), P450c17 (CYP17), 17beta-hydroxysteroid dehydrogenase (17beta-HSD) were assayed on post natal day (PND) 28, 70, 120, 240 and 360 while 5alpha-reducatase was assayed on PND 28. At PND 28, 3beta-HSD activity was elevated by approximately 50% in rats receiving 1046.6 mg total isoflavones/kg feed compared to those on the casein only diet. A similar increase in activity was observed for CYP17 in rats receiving 235.6 mg total isoflavones/kg feed, a level representative of infant exposure through formula, compared to those receiving 0mg isoflavones from the casein diet. These results demonstrate that rats fed a mixture of dietary soy isoflavones showed significantly altered enzyme activity profiles during development at PND 28 as a result of early exposure to isoflavones at levels obtainable by humans.

Licorice reduces serum testosterone in healthy women

Licorice has been considered a medicinal plant for thousands of years. The most common side effect is hypokalemic hypertension, which is secondary to a block of 11beta-hydroxysteroid dehydrogenase type 2 at the level of the kidney, leading to an enhanced mineralocorticoid effect of cortisol. We have investigated the effect of licorice on androgen metabolism in nine healthy women 22-26 years old, in the luteal phase of the cycle. They were given 3.5 g of a commercial preparation of licorice (containing 7.6% W.W. of glycyrrhizic acid) daily for two cycles. They were not on any other treatment. Plasma renin activity, serum adrenal and gonadal androgens, aldosterone, and cortisol were measured by radioimmunoassay. Total serum testosterone decreased from 27.8+/-8.2 to 19.0+/-9.4 in the first month and to 17.5+/-6.4 ng/dL in the second month of therapy (p<0.05). It returned to pre-treatment levels after discontinuation. Androstenedione, 17OH-progesterone, and LH levels did not change significantly during treatment. Plasma renin activity and aldosterone were depressed during therapy, while blood pressure and cortisol remained unchanged.

CONCLUSIONS

Licorice can reduce serum testosterone probably due to the block of 17-hydroxysteroid dehydrogenase and 17-20 lyase. Licorice could be considered an adjuvant therapy of hirsutism and polycystic ovary syndrome.

Inhibition of rat testis microsomal 3beta-hydroxysteroid dehydrogenase activity by tributyltin

In this study, we have examined the effects of a range of organotin compounds (mono-, di-, tributyltin, mono-, di-, trioctyltin) on the activities of rat testis microsomal 3beta-hydroxysteroid dehydrogenase (3beta-HSD), 17-hydroxylase (17-OHase) and 17beta-hydroxysteroid dehydrogenase (17beta-HSD). 17-OHase activity was inhibited by more than 50% compared with the control rate by 59 microM tributyltin (TBT) but other organotin compounds showed no inhibition. 17beta-HSD activity was unaffected by all organotins tested. 3beta-HSD was inhibited by monooctyltin (81 microM) and by TBT at all concentrations tested in a dose-dependent manner, with almost complete loss of activity at TBT concentrations of 12 microM. The mechanism of inhibition of 3beta-HSD was investigated in kinetic analysis with 0-12 microM TBT. Three rat testis microsomal preparations were incubated with dehydroepiandrosterone as the steroid substrate ranging from 1 to 10,000 nM. Tributyltin was primarily a competitive inhibitor of 3beta-HSD activity, causing an increase in the value of the K(m(app)). However, the mechanism was not entirely competitive as while there was an increase in K(m(app)), a decrease in the V(max(app)) was also observed with increasing concentrations of TBT. Slope and intercept replots demonstrated that the K(i)((app)) from slope replots was around 2.7 microM whereas the K(i)((app)) value from intercept replots was around 30 microM. When compared with the K(m(app)) for 3beta-HSD of around 0.42 microM, TBT could be an effective inhibitor of this enzyme.

17-Hydroxysteroid dehydrogenases of Mycobacterium sp. VKM Ac-1815D mutant strain

Whole cells and crude extract of Mycobacterium sp. VKM Ac-1815D mutant strain Et1 were shown to carry out 17beta-reduction, 17beta-dehydrogenation and 1(2)-reduction of 3-keto-C(19)-steroids. Two 17-hydroxy steroid dehydrogenases (17-OH SDH) were partially purified from the strain by ammonium sulfate fractionation, ion-exchange chromatography on DEAE-sephacel and gel-filtration on Bio-Gel A. The enzymes differed in chromatographic properties and specific activities. One enzyme--17-OH SDH (2) (tetramer, M(r) approximately 210,000) was found to be responsible for bi-directional reduction-oxidation of steroids at C 17, whereas the other one--17-OH SDH (1) (monomer, M(r) approximately 68,000) specifically catalysed 17beta-dehydrogenation of 17-hydroxysteroids (testosterone and 1(2)-dehydro testosterone). The 17beta-reduction of 1-ene-17-ketosteroids was accompanied by 1(2)-reduction. A role of 1-ene-reductase as a steroid-binding protein associated with 17-OH SDH (2) in Mycobacterium sp. is discussed.

Exposure to octylphenol increases basal testosterone formation by cultured adult rat Leydig cells

4-Tert-octylphenol (OP) is a breakdown product of 4-tert-octylphenol ethoxylate, which is a surfactant additive widely used in the manufacture of a variety of detergents and plastic products. OP has been reported to exhibit weak estrogenic activity in many assay systems. The studies described herein examined an unusual effect of OP in increasing constitutive testosterone levels of cultured Leydig cells from young adult rats. The increase in testosterone was both dose and time sensitive, and this response was observed in medium lacking both calcium and magnesium and containing a membrane-permeable calcium chelator, suggesting that the increase in testosterone was not mediated by an increase in the permeability of extracellular calcium into cells or the redistribution/release of calcium from intracellular stores, respectively. Cellular cAMP levels also were unaffected by OP alone in cultured Leydig cells. Furthermore, initial exposure to 2000nM OP alone for 4h did not alter the subsequent conversion of endogenous cholesterol or exogenously added 22 (R)hydroxycholesterol to testosterone, suggesting that the increase in testosterone was not due to the enhanced availability of endogenous cholesterol or an increase in cholesterol side-chain cleavage activity, respectively. The increase in testosterone also was observed in the presence of the pure estrogen antagonist, ICI 182,780, or a 5alpha-reductase inhibitor, suggesting that this effect of OP was not mediated through the estrogen receptor alpha or beta pathway or by inhibition of Leydig cell testosterone metabolism, respectively. In addition, exposure of cells to comparable concentrations of two different detergents, Triton X-100 or sodium cholate, did not increase testosterone levels, suggesting that this effect of OP was not due to its potential detergent qualities. Although these studies did not identify specific mechanism(s) that increase constitutive testosterone levels by OP, they identify specific pathways that appear not to be involved. The physiological relevance of this observation is not known; nevertheless, they illustrate potential diverse actions of OP in modulating the level of androgen secreted by Leydig cells, and they emphasize that some actions of OP do not appear to be mediated through the estrogen receptor alpha or beta pathway.

Analysis and characteristics of multiple types of human 17beta-hydroxysteroid dehydrogenase

Androgens and estrogens are not only synthesized in the gonads but also in peripheral target tissues. Accordingly, recent molecular cloning has allowed us to identify multiple types of 17beta-hydroxysteroid dehydrogenases (17beta-HSD), the key and exclusive enzymes involved in the formation and inactivation of sex steroids. However, only one form, namely, type 3 17beta-HSD, is responsible for pseudohermaphroditism in deficient boys. To date, seven human 17beta-HSDs have been isolated and characterized. Although they catalyze substrates having a similar structure, 17beta-HSDs have very low homology. In intact cells in culture, these enzymes catalyze the reaction in a unidirectional way - types 1, 3, 5 and 7 catalyze the reductive reaction, while types 2, 4 and 8 catalyze the oxidative reaction. It is noteworthy that rat type 6 17beta-HSD also catalyzes the reaction in the oxidative direction. In this report, we analyze the different characteristics of the multiple types of human 17beta-HSD.

Studies on methotrexate effects on testicular steroidogenesis in rats

The effects of single dose, 4 consecutive days, 4 and 8 weekly doses of methotrexate (MTX) treatment (3 mg/kg body weight, intramuscularly) with and without leucovorin (LCN) supplementation (0.3 mg/kg body weight, intramuscularly) on serum testosterone titres, total, free and esterified cholesterol concentrations and steroidogenic enzymes, viz. 3beta- and 17beta-hydroxy steroid dehydrogenase activities were studied in adult albino rats. MTX treatment caused a marked reduction in serum testosterone titres in all the treatment groups in a duration-dependent manner. LCN supplementation did not restore serum testosterone titres to normalcy. Total and free cholesterol concentrations remained unaltered in both MTX and MTX + LCN treated groups. On the other hand, a marked increase in esterified cholesterol concentration was evident only in weekly dose treatment groups. The specific activities of 3beta- and 17beta-hydroxy steroid dehydrogenase were markedly diminished in both MTX and MTX + LCN treated groups. The results suggest the inhibitory effect of MTX on steroidogenesis.

Essential role of adenosine triphosphate in activation of 17beta-hydroxysteroid dehydrogenase in the rat Leydig cell

The forskolin-induced steroidogenic block of testosterone production residing beyond pregnenolone synthesis in rat Leydig cells was localized to the level of the 17beta-hydroxysteroid dehydrogenase (17betaHSD) reaction in this study. The use of forskolin analogs that discriminate between the diterpene's inhibitory effect on the glucose transporter(s) (1,9-dideoxyforskolin) and its activation of adenylate cyclase (6-aminoethyl carbamyl forskolin) revealed that the block is related to inhibition of glucose transporter(s). 1,9-Dideoxyforskolin, but not 6-aminoethyl carbamyl forskolin, caused a significant inhibition of basal and hCG-stimulated testosterone production with accumulation of androstenedione. Glucose-deficient media produced the same metabolic block in the absence of forskolin, with a significant reduction in 17betaHSD activity and increases in the apparent Km for androstenedione. In contrast, metabolic steps before testosterone formation were not affected. Glucose-induced 17betaHSD activation was mimicked by the addition of ATP or GTP in glucose-deficient media, but not by nonhydrolyzable triphosphate analogs or NADPH. A decrease in 17betaHSD activity caused by KT-5720, a specific inhibitor of protein kinase A and the calmodulin antagonist W-7, indicates that the ATP requirement may be related to the participation of protein kinases in the activation of 17betaHSD. ATP levels derived from alternative (nonglycolytic) pathways are adequate to support basal and hormone-stimulated enzymatic activities in the metabolism of cholesterol to androstenedione. However, the integrity of the glucose transport system with subsequent ATP generation is required for activation of 17betaHSD in the final step of androgen biosynthesis. In conclusion, the conversion of androstenedione to testosterone requires the contribution of the glycolytic pathway to meet ATP requirements for 17betaHSD activity.

The key role of 17 beta-hydroxysteroid dehydrogenases in sex steroid biology

17 beta-Hydroxysteroid dehydrogenase (17 beta-HSD) controls the last step in the formation of all androgens and all estrogens. This crucial role of 17 beta-HSD is performed by at least five 17 beta-HSD isoenzymes having individual cell-specific expression, substrate specificity, regulation mechanisms, and reductive or oxidative catalytic activity. Both estrogenic and androgenic 17 beta-HSD activities were found in all 25 rhesus monkey and 15 human peripheral intracrine tissues examined. Type 1 17 beta-HSD is a protein of 327 amino acids catalyzing the formation of 17 beta-estradiol from estrone. Its x-ray structure was the first to be determined among mammalian steroidogenic enzymes. Initially crystallized with NAD, the crystal structure of type 1 17 beta-HSD has just been determined as a complex with 17 beta-estradiol, thereby illustrating the conformation of the substrate-binding site. Type 2 17 beta-HSD degrades 17 beta-estradiol into estrone and testosterone into androstenedione, and type 4 17 beta-HSD mainly degrades 17 beta-estradiol into estrone and androst-5-ene-3 beta, 17 beta-diol into dehydroepiandrosterone. Types 3 and 5 17 beta-HSD, on the other hand, catalyze the formation of testosterone from androstenedione in the testis and peripheral tissues, respectively. The various types of human 17 beta-HSD, because of their tissue-specific expression and substrate specificity, provide each peripheral cell with the necessary mechanisms to control the level of intracellular androgens and/or estrogens, a new area of hormonal control that we call intracrinology.

Characteristics of human types 1, 2 and 3 17 beta-hydroxysteroid dehydrogenase activities: oxidation/reduction and inhibition

Following transfection of types 1, 2 and 3 17 beta-hydroxysteroid dehydrogenase (17 beta-HSD) cDNAs into transformed embryonal kidney (293) cells, we have characterized the selective directional and inhibitory characteristics of these activities. While homogenates of transfected cells could catalyze interconversion of the substrate and product, in agreement with the general belief on the activity of these enzymes, the same activities measured in intact cells, in order to better reflect the physiological conditions, showed an unidirectional reaction. Types 1 and 3 17 beta-HSD catalyzed the reduction of estrone to estradiol and 4-androstenedione to testosterone, respectively, while type 2 17 beta-HSD catalyzed the oxidative transformation of both testosterone and 17 beta-estradiol to 4-androstenedione and estrone, respectively. In addition, types 1, 2 and 3 17 beta-HSD activities showed different pH optima. While types 1 and 3 showed pH optimum values centered at around 5 and 6, respectively, type 2 17 beta-HSD activity, which preferentially, catalyzes the oxidation reaction, has higher activity at an alkaline pH (8-10). Differences in the optimum incubation temperatures were also observed: type 1 17 beta-HSD shows a relatively high temperature tolerance (55 degrees C). In contrast, type 2 and 3 functioned best at 37 degrees C. Types 1, 2 and 3 17 beta-HSD activities could be also differentiated by their sensitivity toward various specific inhibitors: type 1 was potently inhibited by an estradiol derivative containing a bromo/or iodopropyl group at position 16 alpha. On the other hand a derivative of estrone containing a spiro-gamma-lactone at position 17 showed a potent inhibitory effect on type 2 17 beta-HSD, whereas type 3 was strongly inhibited by 1,4-androstadiene-1,6,17- trione.

Effect of PCBs on androgen production by suspension of adult rat Leydig cells in vitro

The effects of PCBs (mixture of 2, 3, 4, 5-tetra; 2, 2', 4, 5, 5'-penta; 2, 2', 3, 3', 6, 6'-hexa and 2, 2', 3, 3', 4, 4', 5, 5'-octa congeners) on androgen production were investigated by suspension of Leydig cells from adult rat testis. hCG-stimulated androgen production was significantly inhibited by PCBs while progesterone level was not affected. Progesterone supported testosterone production was also decreased by PCBs, while conversion of androstenedione to testosterone was unchanged. These results suggest that the activity of microsomal enzyme C21 side-chain cleavage P450 was decreased by PCB treatment of Leydig cells in vitro.

Formation and degradation of dihydrotestosterone by recombinant members of the rat 3 beta-hydroxysteroid dehydrogenase/delta 5-delta 4 isomerase family

The structures of cDNA clones encoding four members of the rat 3 beta-hydroxysteroid dehydrogenase/delta 5-delta 4 isomerase (3 beta-HSD) family were characterized. The rat type I, type II and the novel type IV are genuine NAD+/H-dependent 3 beta-HSD isoenzymes. On the other hand, the liver-specific type III protein is a specific 3-keto-reductase (3-KSR) that catalyzes the conversion of 5 alpha-androstane-3-one-17 beta-ol (DHT) and 5 alpha-androstane 3,17-dione (A-dione) into their 3 beta-hydroxy metabolites. The aim of the present study was to further characterize the enzymatic properties of rat types I, III and IV, especially their role in the formation and degradation of DHT after transient expression in intact human HeLa cervical carcinoma, JEG-3 choriocarcinoma or SW-13 adrenal cortex adenocarcinoma cells in culture. The expressed type III 3-KSR in intact HeLa cells catalyzed the reduction of DHT into 3 beta-diol, whereas expression of type I 3 beta-HSD in these cell lines had no significant effect on the basal conversion of DHT into 3 beta-diol, but it did increase the formation of DHT from 3 beta-diol. A-dione is the predominant product obtained when DHT and 5 alpha-androstane-3 beta, 17 beta-diol (3 beta-diol) are used as substrates in intact JEG-3 and SW-13 cells transfected with rat type I 3 beta-HSD. Furthermore, this predominant 17 beta-HSD activity was also observed in SW-13 cells transfected with the novel rat type IV 3 beta-HSD. The predominance of this 'secondary' 17 beta-HSD activity is also reflected in HeLa cells transfected with type I 3 beta-HSD by the deduced predominant pathway 3 beta-diol-->DHT-->5 alpha-androstane-3 alpha,17 beta-diol (3 alpha-diol)-->androsterone (ADT), in which formation of 3 alpha-HSD activity of HeLa cells, whereas the other reactions are catalyzed by the type I 3 beta-HSD isoenzyme. This observation thus demonstrates that rat type I 3 beta-HSD may also catalyze the conversion of 3 alpha-diol into ADT through its intrinsic 17 beta-HSD activity. The predominant metabolic pathways observed in the present study could be attributed to preponderant bioavailability of NAD+ and NADPH in the intact transfected cells used.

Placental 17 beta-hydroxysteroid oxidoreductase, lactate dehydrogenase and malate dehydrogenase during the latter half of pregnancy in the mouse

The specific activity of 17 beta-hydroxysteroid oxidoreductase (17-HOR) with estradiol-17 beta (E2), estrone (E1) and testosterone (T), as well as that of lactate dehydrogenase (LDH) and malate dehydrogenase (MDH) were measured in homogenates of CF-1 mouse placenta during the latter half of pregnancy. 17-HOR activity with E2 and T increased over 100-fold between days 9 and 12, and 3- to 4-fold between days 15 and 19, with no further change to day 21. In contrast, activity with E1 increased 39-fold between days 9 and 12, 3.8-fold between days 15 and 19 but then decreased between days 19 and 21. The E2/T activity ratio was constant while the E2/E1 ratio increased between days 9 and 21. LDH increased 2-fold between days 9 and 12 with no further increase to day 19. MDH was constant from day 9 to 19. Activity with E2 was inhibited by T, 5 alpha-dihydrotestosterone (5 alpha-DHT) and DHA but not by E1, androstenedione (A) or 20 alpha-dihydroprogesterone. Activity with T was inhibited by E2, 5 alpha-DHT and DHA, but not by A. In contrast, activity with E1 was inhibited by A and DHA but not by E2, T or 5 alpha-DHT. The results suggest placental 17-HOR is developmentally regulated. Although the results are also suggestive of multiple forms of 17-HOR, a single enzyme with an ordered kinetic mechanism cannot be ruled out.

17 beta-hydroxysteroid oxidoreductase in epithelium and stroma of human prostate

It is conceivable that androstenedione contributes indirectly to 5 alpha-dihydrotestosterone formation in human prostate by its intraprostatic conversion to testosterone. This reversible conversion is catalyzed by the enzyme 17 beta-hydroxysteroid oxidoreductase (17 beta-HSOR). At present, rather limited information on kinetic parameters like specific concentration (Vmax), affinity to steroid substrates (KmS) and to pyridine nucleotides (KmN) of 17 beta-HSOR is available. Thus, we determined those aforementioned kinetic parameters in epithelium and stroma of normal human prostate (NPR) and benign prostatic hyperplasia (BPH). The main results were: (1) the mean KmS of 17 beta-HSORred/NADPH was significantly (P < 0.0001) lower than those of all other 17 beta-HSORs. (2) In almost all cases the mean Vmax was higher in BPH than NPR. (3) In all cases, the mean Vmax/KmS ratios of 17 beta-HSORred were higher than those of 17 beta-HSORox. The highest ratio was found regarding 17 beta-HSORred/NADPH in BPH stroma. (4) In stroma, a significantly positive correlation of Vmax/KmS of 17 beta-HSORred/NADPH with age was found. (5) The lowest KmN was found regarding NADP+, followed by NADPH. It is concluded that in human prostate the balance of the reversible conversion of testosterone to androstenedione is shifted potentially towards testosterone, particularly in BPH stroma.

Identification of phospholipids capable of modulating the activities of some enzymes involved in androgen and 16-androstene biosynthesis in the immature pig testis

Testicular steroidogenic enzymes in the microsomal fraction from immature pigs were investigated for the effects of phospholipids of known structure on androgen and 16-androstene biosynthesis. Untreated (control) microsomes metabolized pregnenolone to 17-hydroxypregnenolone, DHA and small quantities of progesterone, 17-hydroxyprogesterone, androstenedione and testosterone; and to 5,16-androstadien-3 beta-ol (andien-beta) and 4,16-androstadienone (dienone) in the 16-androstene pathway. Phosphatidyl(P)-serine, P-glycerol, P-ethanolamine, P-inositol, P-choline and phosphatidic acid did not significantly alter the 17-hydroxylase/C-17,20 lyase or "andien-beta-synthetase" activities. Thus, the C21 side-chain cleavage reactions appeared not to be dependent upon phospholipids for optimal activity. The conversion of pregnenolone to 4-ene steroids (progesterone, 17-hydroxyprogesterone, androstenedione and testosterone) was inhibited by dilinoleoyl-phosphatidyl-choline, but other phospholipids tested were without effect. On the other hand, the conversion of andien-beta to dienone was inhibited by P-serine, P-inositol and P-cholines with short saturated or long polyunsaturated acyl chains. Therefore, the presence of these phospholipids in pregnenolone incubations had different consequences for 3 beta-hydroxysteroid dehydrogenase-isomerase activities. It is concluded that substrate specific 3 beta-HSD-isomerases exist for androgen and 16-androstene biosynthesis and that phospholipids may play an intrinsic role in their catalytic activity.

Human ovarian 17-ketosteroid oxidoreductase: unique characteristics of the granulosa-luteal cell and stromal enzyme

OBJECTIVES

We attempted to test the hypothesis that distinct forms of the 17-ketosteroid oxidoreductase exist in the human ovary and to compare its activity in stroma obtained from normally cycling women and from hyperandrogenic women.

STUDY DESIGN

Human ovarian granulosa-luteal cell and stromal 17-ketosteroid oxidoreductase were examined in cell incubations and subcellular homogenates.

RESULTS

In subcellular homogenates of granulosa-luteal cells 17-ketosteroid oxidoreductase activity was greater in the cytosol fraction than in the membrane fraction. In contrast, in homogenates of both ovarian stroma and Leydig cells its activity was greater in the membrane fraction than in the cytosol fraction. At the substrate concentrations used estrone was a better substrate than androstenedione for the granulosa-luteal cell 17-ketosteroid oxidoreductase. In contrast, androstenedione was a better substrate than estrone for that in ovarian stromal and Leydig cell membranes. In incubations of ovarian stroma from hyperandrogenic women, significantly more testosterone accumulated in the medium per milligram of tissue than in the medium of incubations of ovarian stroma from normally cycling women (142 +/- 48 vs 7.9 +/- 7.5 pg testosterone per milligram of tissue per 48 hours, mean +/- SD, p less than 0.05). The ratio of testosterone to androstenedione was significantly higher in the medium of incubations of ovarian stroma from hyperandrogenic women than in that from normally cycling women (0.61 vs 0.25, mean, p less than 0.05). The ratio of serum testosterone to androstenedione was significantly greater in hyperandrogenic women than in normally cycling control women (0.31 +/- 0.11 vs 0.20 +/- 0.03, mean +/- SD, p less than 0.05).

CONCLUSION

The localization (cytosol fraction) and substrate specificity (estrone) of the granulosa-luteal cell 17-ketosteroid oxidoreductase enzyme resembles that seen in human placenta. The localization (membrane fraction) and substrate specificity (androstenedione) of the ovarian stromal 17-ketosteroid oxidoreductase enzyme resembles that seen in Leydig cells. It may be one enzyme that exists in multiple forms or it may be two (or more) enzymes. In some hyperandrogenic women the ovarian stromal 17-ketosteroid oxidoreductase may be more active than in normally cycling women, contributing to an abnormally increased testosterone production rate.

Distribution of 17 beta-hydroxysteroid dehydrogenase gene expression and activity in rat and human tissues

The interconversion of estrone (E1) and 17 beta-estradiol (E2), androstenedione (4-ene-dione) and testosterone (T), as well as dehydroepiandrosterone and androst-5-ene-3 beta,17 beta-diol is catalyzed by 17 beta-hydroxysteroid dehydrogenase (17 beta-HSD). The enzyme 17 beta-HSD thus plays an essential role in the formation of all active androgens and estrogens in gonadal as well as extragonadal tissues. The present study investigates the tissue distribution of 17 beta-HSD activity in the male and female rat as well as in some human tissues and the distribution of 17 beta-HSD mRNA in some human tissues. Enzymatic activity was measured using 14C-labeled E1, E2, 4-ene-dione and T as substrates. Such enzymatic activity was demonstrated in all 17 rat tissues examined for both androgenic and estrogenic substrates. While the liver had the highest level of 17 beta-HSD activity, low but significant levels of E2 as well as T formation were found in rat brain, heart, pancreas and thymus. The oxidative pathway (E2----E1, T----4-ene-dione) was favored over the reverse reaction in almost all rat tissues while in the human, almost equal rates were found in most of the 15 tissues examined. The widespread distribution of 17 beta-HSD in rat and human tissues clearly indicates the importance of this enzyme in peripheral sex steroid formation or intracrinology.

Phospholipases modulate immature pig testicular androgen and 16-androstene biosynthetic pathways in vitro

The role of membrane phospholipids in porcine testicular androgen and 16-androstene biosynthesis was examined by monitoring the effects of phospholipase treatments on the activities of the steroid transforming enzymes. Untreated (control) microsomes from immature pig testes converted pregnenolone to 17-hydroxypregnenolone and DHA to 5,16-androstadien-3 beta-ol (andien-beta) and 4,16-androstadien-3-one (dienone) in the 16-androstene pathway, these metabolites accounting for most (65%) of the pregnenolone converted. The 4-ene steroids in the androgen pathway (progesterone, 17-hydroxyprogesterone, androstenedione and testosterone) totalled less than 10% of the pregnenolone metabolites. No estrogens or 5 alpha-reduced metabolites were detected. Treatment with phospholipase A2 or C, decreased the conversion of pregnenolone to 4-ene-3-oxo steroids but did not decrease the quantities of 5-ene-3 beta-hydroxysteroids. Confirmation of these findings was obtained by measuring the individual enzymatic steps. Phospholipases A2 and C significantly reduced the conversion of DHA to androstenedione and andien-beta to dienone but did not affect 17-hydroxylase or 'andien-beta-synthetase'. However, when the C-17, 20 lyase step was measured alone, phospholipase C decreased the quantity of androstenedione produced indicating that the side-chain cleavage reaction may involve a lipid component. The different effects of phospholipases on these enzymes suggests that pregnenolone metabolism may be regulated by alterations in the membrane microenvironment.

Ethanol-induced inhibition of testosterone biosynthesis in rat Leydig cells: role of culture medium composition

The biochemical mechanisms responsible for the ethanol-induced inhibition of testicular testosterone synthesis were studied in isolated rat Leydig cells in vitro. This inhibition was removed when HAM-F12 nutrient mixture was added to the DME culture medium. The components of HAM-F12, i.e. vitamins, amino acids and other supplements, were tested individually and the amino acids L-glutamate (Glu) and L-aspartate (Asp) were found to potentiate strongly the hCG stimulated testosterone synthesis. None of the other components of HAM-F12 had any effect upon testosterone synthesis or its ethanol-induced inhibition. Moreover, Glu, but not Asp, effectively reversed the acute inhibition of steroidogenesis by ethanol. These results demonstrate the importance of the composition of the culture media and provide the first piece of evidence that the metabolic stress in rat Leydig cells in vitro induced by the metabolism of ethanol can be overcome by proper culture medium supplementation.

Rat Leydig cell and granulosa cell 17-ketosteroid reductase activity: subcellular localization and substrate specificity

The potent gonadal steroids testosterone and estradiol are synthesized from the biologically weak precursors, androstenedione and estrone, by enzymatic reduction of the ketone group at carbon-17 of the steroid nucleus (17-ketosteroid reductase). To test the hypothesis that Leydig and granulosa cells may contain a distinct 17-ketosteroid reductase enzyme, the subcellular localization and the substrate specificity of the enzyme was examined in each cell type. In Leydig cells, the 17-ketosteroid reductase activity was concentrated in the microsomal fraction of the cell. In granulosa cells, the 17-ketosteroid reductase activity was concentrated in the cytosolic fraction of the cell. In Leydig cell microsomes, the apparent Michaelis-Menten constant for the conversion of androstenedione to testosterone was 0.41 mumol/L and for the conversion of estrone to estradiol it was 12 mumol/L. In granulosa cell cytosol, the apparent Michaelis-Menten constant for the conversion of estrone to estradiol was 1.1 mumol/L and for the conversion of androstenedione to testosterone it was 15 mumol/L. These results demonstrate that rat Leydig and granulosa cells each contain a 17-ketosteroid reductase enzyme with unique subcellular localization and substrate specificity.

17 beta-hydroxysteroid dehydrogenase activity in canine pancreas

The mitochondrial fraction of the dog pancreas showed NAD(H)-dependent enzyme activity of 17 beta-hydroxysteroid dehydrogenase. The enzyme catalyzes oxidoreduction between androstenedione and testosterone. The apparent Km value of the enzyme for androstenedione was 9.5 +/- 0.9 microM, the apparent Vmax was determined as 0.4 nmol mg-1 min-1, and the optimal pH was 6.5. In phosphate buffer, pH 7.0, maximal rate of androstenedione reduction was observed at 37 degrees C. The oxidation of testosterone by the enzyme proceeded at the same rate as the reduction of the androstenedione at a pH of 6.8-7.0. The apparent Km value and the optimal pH of the enzyme for testosterone were 3.5 +/- 0.5 microM and 7.5, respectively.

Estrogen metabolism by primary cultures of rat ventral prostate epithelial and stromal cells

Estrogen metabolism was examined in primary cultures of rat ventral prostate epithelial and stromal cells developed from young (approximately 3 weeks old) animals. Supraphysiologic concentrations (50 nM) of tritium-labelled estradiol (E2) and estrone (E1) were incubated separately with each cell type and the metabolites formed were measured at selected time points over a 24 h period. The metabolites were analyzed using high performance liquid chromatography. Epithelial cells exhibited an equal capability to interconvert E2 and E1 thus demonstrating the presence of similar oxidative and reductive activities for 17 beta-hydroxysteroid oxidoreductase (17 beta-HSOR) [0.45 and 0.40 pmol/3 h/microgram DNA respectively]. In contrast, stromal cells showed a 6-fold lower rate of oxidation of E2 to E1 (0.08 pmol/3 h/microgram DNA) but exhibited an approx 5-fold higher rate of reduction of E1 to E2 (1.81 pmol/3 h/microgram DNA). Estriol (E3) formation from either substrate was not detected in the two cell types. The results demonstrate that rat ventral prostate epithelial cells have similar capabilities to form or remove biologically active E2. In contrast, prostate stromal cells exhibited a preferential capability to form and possibly maintain high levels of biologically active E2. These findings are discussed with reference to the actions of estrogens on prostate epithelial-stromal cellular interactions.

Differential effects of combinations of phospholipase A2 and phospholipase C on the activity of rat epididymal nuclear and microsomal 4-ene steroid 5 alpha-reductase

Epididymal 4-ene steroid 5 alpha-reductase converts testosterone to 5 alpha-dihydrotestosterone. The enzyme is localized to the nuclear and microsomal fractions, and the activity can be altered by modifying the phospholipids in the membrane environment. To investigate the membrane dependence of 4-ene steroid 5 alpha-reductase, we have treated nuclear and microsomal membranes with combinations of phospholipase A2 and phospholipase C, and examined the effects on 4-ene steroid 5 alpha-reductase activity. Sequential addition of phospholipase A2 and phospholipase C to the nuclear fraction, reduced the 4-ene steroid 5 alpha-reductase activity to approx 25% of the control level. Neither the nature of the phospholipase, nor the sequence of addition altered the inhibition. When both phospholipases were added simultaneously, nuclear 4-ene steroid 5 alpha-reductase activity was inhibited in a linear fashion, and in tests for cooperativity, the effects of phospholipase A2 and phospholipase C were clearly additive. The microsomal enzyme responded differently to sequential phospholipase treatments; if phospholipase A2 was followed by phospholipase C, or phospholipase C followed by phospholipase A2, the 4-ene steroid 5 alpha-reductase activity was, respectively, 13 and 27% of the control. In contrast, sequential addition of the same phospholipase reduced the activity of 4-ene steroid 5 alpha-reductase to approx 40% of the control level. Furthermore, simultaneous addition of phospholipase A2 and phospholipase C to the microsomal fraction, resulted in non-linearity of 4-ene steroid 5 alpha-reductase activity with time, whereas when added individually, linearity of 4-ene steroid 5 alpha-reductase was maintained. Consequently, it was not possible to test for cooperative effects of phospholipases on the microsomal 4-ene steroid 5 alpha-reductase. These findings suggest that for the nuclear 4-ene steroid 5 alpha-reductase, the polar and non-polar regions of the membrane environment have similar functions, which are most likely involved in the maintenance of the structural integrity of the enzyme. For the microsomal enzyme, the polar and non-polar regions of the membrane appear to have different functions, not only for the maintenance of enzyme integrity, but also in the mechanism at the active site.

Incomplete masculinization due to a deficiency of 17 beta-hydroxysteroid dehydrogenase: comparison of prepubertal and peripubertal siblings

Incomplete masculinization due to a deficiency of 17 beta-hydroxysteroid dehydrogenase (17 beta-HSD) was investigated in siblings aged 4 years (Case 1) and 12 years (Case 2). Diagnosis was based on increased ratios of androstenedione (A) to testosterone (T) in blood, and impaired reduction of A to T by 17 beta-HSD in vitro in the testes. Impairment was total in Case 2 but partial in Case 1. Case 2 also showed deficient conversion of dehydroepiandrosterone (DHA) to androstenediol and of oestrone to oestradiol by 17 beta-HSD which were normal in Case 1. Oxidation of T to A by 17 beta-HSD and conversion of 17 alpha-hydroxyprogesterone to A by 17,20 desmolase were normal in the testes of both siblings. 3 beta-HSD conversion of DHA to A was normal in Case 1, but markedly increased in Case 2. In contrast to testicular findings, 17 beta-HSD reduction of A to T in genital skin fibroblasts from Case 2 was normal and diagnosis would not have been possible from studies of measurements of this enzyme in skin. The severity of the testicular 17 beta-HSD deficiency in the peripubertal compared with the prepubertal sibling suggests either considerable intra-familial variation in the extent of the enzyme defect or that puberty may aggravate this disorder. The normal reductive action of 17 beta-HSD in skin, despite impaired action in testes, suggests involvement of more than one iso-enzyme.

On the in vitro metabolism of androstenedione and progesterone in human testicular tissue from fetal age to senescence

The conversion of [3H]-androstenedione to testosterone regulated by the enzyme 17 beta-ketosteroid reductase and the conversion of [3H]-progesterone to 17 alpha-hydroxyprogesterone and onwards along the delta 4 metabolic pathway was studied in vitro in human testicular tissue from 32 males (2 fetuses, 25 adult, infertile men and 5 elderly men with prostatic carcinoma). Additionally, two prepubertal boys were studied with respect to the conversion of [3H]-androstenedione to testosterone in vitro, whereas another seven boys were studied with reference to the conversion of [3H]-progesterone in vitro. It appeared, that in all cases, the conversion of androstenedione to testosterone was larger than the conversion of progesterone to 17 alpha-hydroxyprogesterone by way of the 17 alpha-hydroxylase and onwards along the delta 4 metabolic pathway. It is thus concluded that the 17 beta ketosteroid reductase is not a rate-limiting enzyme along the delta 4 metabolic pathway. No case of deficient 17 beta-ketosteroid reductase was found among the 25 infertile patients studied.

Semen characteristics and serum and seminal plasma hormones in drug-induced hyperprolactinaemia

Semen volume, density, motility, viability, and morphology of spermatozoa, and serum and seminal plasma levels of the hormones FSH, LH, prolactin, progesterone, 17-alpha-hydroxyprogesterone, androstenedione, testosterone, dihidrotestosterone, and estradiol 17-beta have been measured in 22 men subjected to experimental hyperprolactinaemia by the simultaneous administration of the antidopaminergic drugs metoclopramide and sulpiride. Hyperprolactinaemia produces a decrease of semen volume and seminal quality. In hyperprolactinaemia, normozoospermic patients had an increase of serum androstenedione. In both normo- and oligozoospermic groups, a decrease of serum testosterone was observed. Hyperprolactinaemia also causes an inhibition of the secretory activity of the accessory sexual glands of the reproductive tract, as well as either a decrease of 17-ketosteroid reductase or an increase of 17-alpha-hydroxysteroid dehydrogenase (enzymes that participate in the androstenedione-testosterone interconversions). This change appears to be more pronounced in individuals with good seminal quality.

Kinetic mechanism of porcine testicular 17 beta-hydroxysteroid dehydrogenase

A study on product inhibition of 17 beta-hydroxysteroid dehydrogenase from porcine testes was carried out by measuring the initial velocities of NADPH formation using testosterone as the substrate steroid. Type of inhibition by NADPH against NADP+ was competitive in both saturated and unsaturated concentrations of testosterone. In the saturated concentration of NADP+, activity of the enzyme was not inhibited by NADPH against testosterone. In the unsaturated concentrations of NADP+, however, NADPH brought mixed type inhibition against testosterone. The similar modes of inhibition by the product steroid, androstenedione were observed in the saturated and unsaturated concentrations of NADP+ and testosterone. The fluorescence of NADPH was increased in the presence of the enzyme, and fluorometric titration indicated that 1 mol of NADPH was bound to 1 mol of the 17 beta-hydroxysteroid dehydrogenase. Addition of testosterone to enzyme-NADPH complex reduced the intensity of fluorescence of NADPH, suggesting formation of testosterone-enzyme-NADPH complex as a ternary dead end complex. From the analyses of product inhibition and spectral changes of NADPH, the kinetic mechanism of the enzyme was revealed as rapid equilibrium random system with two dead end complexes which consisted of the two reduced reactants bound to the enzyme and the two oxidized ones bound to it.