Evaluation of the protective effects of icariin on nicotine-induced reproductive toxicity in male mouse -a pilot study

BACKGROUND

Nicotine, a pharmacologically active component of tobacco adversely affects the male reproductive system and fertility whereas icariin (ICA), the main active ingredient in Epimedium herba has been used in the treatment of several male reproductive problems. This study aimed at evaluating the protective or ameliorative effect of ICA against reproductive toxicity induced by intraperitoneal injection of nicotine in mice.

METHODS

Using simple random allocation, forty male mice were randomly divided into 4 groups: control (received 0.35 mL physiological saline via gastric gavage), nicotine (0.75 mg/kg BW/day intraperitoneally), ICA (75 mg/kg BW/day gastric gavage), and nicotine plus ICA (nicotine, 0.75 mg/kg BW/day intraperitoneally + ICA, 75 mg/kg BW/day gastric gavage) group. After 35 days of treatment, the mice were weighed, sacrificed, and their reproductive organs (testis and epididymis) were collected and examined for further studies.

RESULTS

The nicotine-treated group showed significantly decreased epididymal sperm density and serum testosterone concentration relative to the control group. Nicotine also caused oxidative damage shown by significant reduction in the activities of antioxidant enzymes and elevation in Malondialdehyde (MDA) levels. ICA on the other hand, improved the reduction in sperm density, hormone levels, and activities of antioxidant enzymes altered in the nicotine treated mice.

CONCLUSIONS

These findings indicate that nicotine-induced reproductive toxicity and oxidative damage on male reproductive tissues could be attenuated by ICA.

Growth Differentiation Factor-8 Decreases StAR Expression Through ALK5-Mediated Smad3 and ERK1/2 Signaling Pathways in Luteinized Human Granulosa Cells

Growth differentiation factor-8 (GDF-8) has been recently shown to be expressed in human granulosa cells, and the mature form of GDF-8 protein can be detected in the follicular fluid. However, the biological function and significance of this growth factor in the human ovary remains to be determined. Here, we investigated the effects of GDF-8 on steroidogenic enzyme expression and the potential mechanisms of action in luteinized human granulosa cells. We demonstrated that treatment with GDF-8 did not affect the mRNA levels of P450 side-chain cleavage enzyme and 3β-hydroxysteroid dehydrogenase, whereas it significantly down-regulated steroidogenic acute regulatory protein (StAR) expression and decreased progesterone production. The suppressive effect of GDF-8 on StAR expression was abolished by the inhibition of the TGF-β type I receptor. In addition, treatment with GDF-8 activated both Smad2/3 and ERK1/2 signaling pathways. Furthermore, knockdown of activin receptor-like kinase 5 reversed the effects of GDF-8 on Smad2/3 phosphorylation and StAR expression. The inhibition of Smad3 or ERK1/2 signaling pathways attenuated the GDF-8-induced down-regulation of StAR and production of progesterone. Interestingly, the concentrations of GDF-8 were negatively correlated with those of progesterone in human follicular fluid. These results indicate a novel autocrine function of GDF-8 to down-regulate StAR expression and decrease progesterone production in luteinized human granulosa cells, most likely through activin receptor-like kinase 5-mediated Smad3 and ERK1/2 signaling pathways. Our findings suggest that granulosa cells might play a critical role in the regulation of progesterone production to prevent premature luteinization during the final stage of folliculogenesis.

Adrenal and Ovarian Phenotype of a Tissue-Specific Urocortin 2-Overexpressing Mouse Model

Urocortin 2 (UCN2) is a neuropeptide of the CRH family, involved in homeostatic mechanisms, the stress response, and control of anxiety. To elucidate the effects of UCN2 on steroidogenesis, we developed a mouse model that allows a Cre recombinase-determined conditional overexpression of UCN2 (UCN2-COE). In these mice SF1-Cre-driven overexpression of UCN2 was restricted to the adrenal glands, gonads, and parts of the hypothalamus. UCN2-COE animals of both sexes revealed significantly higher plasma UCN2 levels and significantly higher UCN2 expression levels in the adrenals and ovaries. In contrast, the baseline expression of UCN2 was already high in the testes of control mice with no further increase achievable in UCN2-COE animals. Adrenal steroidogenesis of UCN2-COE animals was investigated under baseline conditions, upon an ACTH stimulation test, and following a restraint stress test. A tendency toward lower expression of steroidogenic enzymes was detectable in UCN2-COE animals of both sexes with slight differences between males and females. A similar reduction in the expression levels of the final steps of ovarian steroidogenesis, accompanied by reduced plasma estradiol levels, was observed in female UCN2-COE animals. Thus, adrenal UCN2 overexpression resulted in down-regulation of adrenal steroidogenesis, suggesting a reduction in the stress response in the mouse (stress coping behavior). Similarly, UCN2 overexpression in the ovaries caused a decrease in steroidogenesis and reduction of follicles that had undergone ovulation. Nevertheless, this finding was not associated with reduced fertility.

AKR1C3 as a target in castrate resistant prostate cancer

Aberrant androgen receptor (AR) activation is the major driver of castrate resistant prostate cancer (CRPC). CRPC is ultimately fatal and more therapeutic agents are needed to treat this disease. Compounds that target the androgen axis by inhibiting androgen biosynthesis and or AR signaling are potential candidates for use in CRPC treatment and are currently being pursued aggressively. Aldo-keto reductase 1C3 (AKR1C3) plays a pivotal role in androgen biosynthesis within the prostate. It catalyzes the 17-ketoreduction of weak androgen precursors to give testosterone and 5α-dihydrotestosterone. AKR1C3 expression and activity has been implicated in the development of CRPC, making it a rational target. Selective inhibition of AKR1C3 will be important, however, due to the presence of closely related isoforms, AKR1C1 and AKR1C2 that are also involved in androgen inactivation. We examine the evidence that supports the vital role of AKR1C3 in CRPC and recent developments in the discovery of potent and selective AKR1C3 inhibitors. This article is part of a Special Issue entitled 'CSR 2013'.

Hypophyseal corticosteroids stimulate somatotrope differentiation in the embryonic chicken pituitary gland

Although it is known that glucocorticoids induce differentiation of growth hormone (GH)-producing cells in rodents and birds, the effect of mineralocorticoids on GH mRNA expression and the origin of corticosteroids affecting somatotrope differentiation have not been elucidated. In this study, we therefore carried out experiments to determine the effect of mineralocorticoids on GH mRNA expression in the chicken anterior pituitary gland in vitro and to determine whether corticosteroids are synthesized in the chicken embryonic pituitary gland. In a pituitary culture experiment with E11 embryos, both corticosterone and aldosterone stimulated GH mRNA expression and increased the number of GH cells in both lobes of the pituitary gland in a dose-dependent manner. These effects of the corticosteroids were significantly reversed by pretreatment with mifepristone, a glucocorticoid receptor (GR) antagonist, or spironolactone, a mineralocorticoid receptor (MR) antagonist. Interestingly, an in vitro serum-free culture experiment with an E11 pituitary gland showed that the GH mRNA level spontaneously increased during cultivation for 2 days without any extra stimulation, and this increase in GH mRNA level was completely suppressed by metyrapone, a corticosterone-producing enzyme P450C11 inhibitor. Moreover, progesterone, the corticosterone precursor, also stimulated GH mRNA expression in the cultured chicken pituitary gland, and this effect was blocked by pretreatment with metyrapone. We also detected mRNA expression of enzymes of cytochrome P450 cholesterol side chain cleavage (P450scc) and 3beta-hydroxysteroid dehydrogenase1 (3beta-HSD1) in the developmental chicken pituitary gland from E14 and E18, respectively. These results suggest that mineralocorticoids as well as glucocorticoids can stimulate GH mRNA expression and that corticosteroids generated in the embryonic pituitary gland by intrinsic steroidogenic enzymes stimulate somatotrope differentiation.

Modulation of steroidogenic gene expression and hormone production of H295R cells by pharmaceuticals and other environmentally active compounds

The H295R cell bioassay was used to evaluate the potential endocrine disrupting effects of 18 of the most commonly used pharmaceuticals in the United States. Exposures for 48 h with single pharmaceuticals and binary mixtures were conducted; the expression of five steroidogenic genes, 3betaHSD2, CYP11beta1, CYP11beta2, CYP17 and CYP19, was quantified by Q-RT-PCR. Production of the steroid hormones estradiol (E2), testosterone (T) and progesterone (P) was also evaluated. Antibiotics were shown to modulate gene expression and hormone production. Amoxicillin up-regulated the expression of CYP11beta2 and CYP19 by more than 2-fold and induced estradiol production up to almost 3-fold. Erythromycin significantly increased CYP11beta2 expression and the production of P and E2 by 3.5- and 2.4-fold, respectively, while production of T was significantly decreased. The beta-blocker salbutamol caused the greatest induction of CYP17, more than 13-fold, and significantly decreased E2 production. The binary mixture of cyproterone and salbutamol significantly down-regulated expression of CYP19, while a mixture of ethynylestradiol and trenbolone, increased E2 production 3.7-fold. Estradiol production was significantly affected by changes in concentrations of trenbolone, cyproterone, and ethynylestradiol. Exposures with individual pharmaceuticals showed the possible secondary effects that drugs may exert on steroid production. Results from binary mixture exposures suggested the possible type of interactions that may occur between drugs and the joint effects product of such interactions. Dose-response results indicated that although two chemicals may share a common mechanism of action the concentration effects observed may be significantly different.

Steroidogenic and structural differentiation of new Leydig cell population following exposure of adult rats to ethane dimethanesulphonate

EDS alkylating agent has been shown to selectively and temporarily kill LCs in adult rats. The first newly formed single LCs appeared at 14th day post ESD and showed detectable activity for 3beta-HSD and NADH2-diaphorase, which became progressively stronger with time after treatment The ultrastructural study revealed that the progenitor LCs differentiated into immature LCs within a week, and two weeks later they were transformed into mature LCs. Therefore, the restoration of new LC population after EDS treatment repeated the dynamics of normal LC development within a similar time range. The dynamics of enzyme activity correlated with structural differentiation of the new LC population.

Effect of prenatal exposure to hydroxyprogesterone on steroidogenic enzymes in male rats

Pregnant Wistar strain albino rats were administered hydroxyprogesterone and the steroidogenic potential of the testis was analysed in the next generation adult male rats. In utero exposure to supranormal levels (10 mg/kg body weight or 25 mg/kg body weight) of hydroxyprogesterone decreased the activity levels of marker steroidogenic enzymes (3beta-hydroxysteroid dehydrogenase and 17beta-hydroxysteroid dehydrogenase) of adult (mature) rat testis. Hydroxyprogesterone mediation in the suppression of rat testicular steroidogenesis is suggested, which can be correlated to the observed decrease in male reproductive potential in mammals exposed to female hormones during embryonic development.

Adrenocorticotrophic hormone (ACTH) stimulation of sheep fetal adrenal cortex can occur without increased expression of ACTH receptor (ACTH-R) mRNA

In the present study, it was hypothesized that the adrenocorticotrophin hormone receptor (ACTH-R) would be up-regulated in the adrenal gland of the sheep fetus following infusion of physiological amounts of ACTH, as shown for adrenal cortical cells in culture. In chronically catheterized sheep, an intravenous infusion of ACTH(1-24) was given to 6 fetuses for 24 h at a rate of 0.5 microg h(-1), starting on Day 126 or 127 of gestation (term approximately 147 days). Four control fetuses received an infusion of vehicle (saline). Total RNA was extracted from the fetal adrenal glands by the guanidinium thiocyanate method. Expression of specific mRNAs was determined by ribonuclease protection assay using cRNA probes directed against: ACTH-R; the steroid enzymes side-chain cleavage (P450scc), 3beta-hydroxysteroid dehydrogenase (3beta-HSD), 17apha-hydroxylase (P450c17) and 21beta-hydroxylase (P450c21); and beta-actin. Ratios of mRNA expression to beta-actin mRNA expression (arbitrary units) were calculated to correct for differences in RNA quality between samples. The concentration (mean +/- SEM) of immunoreactive cortisol in fetal plasma was greater after ACTH infusion than after vehicle infusion (47 +/- 3 v. 13 +/- 2 ng mL(-1) respectively; P<0.001). Adrenal expression of P450scc and P450c21 mRNA increased after ACTH infusion (P<0.05), whereas expression of P450c17 and 3beta-HSD mRNA was unchanged. There was no difference in ACTH-R mRNA expression between ACTH- and vehicle-infused fetuses (254 +/- 48 v. 305 +/- 76 arbitrary units respectively). It was concluded that ACTH is able to increase plasma cortisol concentrations in the sheep fetus by up-regulating cortisol synthesis in the adrenal gland, but that in vivo this does not require up-regulation of ACTH-R mRNA.

Concentration dependency in lead-inhibited steroidogenesis in MA-10 mouse Leydig tumor cells

Lead acetate (Pb) decreases the expression of steroidogenic acute regulatory (StAR) protein and the enzymatic activities of cytochrome P-450 side-chain cleavage (P450scc) and 3beta-hydroxysteroid dehydrogenase (3beta-HSD) in a concentration-dependent manner in Leydig cells at 2 h, the duration of submaximal inhibition. This study was undertaken at 3 h of Pb incubation to compare the effects at maximal metal inhibition of steroidogenesis. Quantitatively a 3-h Pb incubation with MA-10 cells resulted in higher decreases in human chorionic gonadotropin (hCG)-stimulated progesterone production, expression of StAR protein, and the activity of 3beta-HSD compared to 2 h. In contrast, lead inhibited dibutyryl cAMP (dbcAMP)-stimulated progesterone production but lacked this effect at 2 h. Surprisingly, Pb at 3 h of incubation did not affect P450scc enzyme activity, yet this enzymatic activity was inhibited at 2 h. Data indicate that incubation time is a factor in Pb-induced alterations in MA- 10 cell steroidogenesis.

Influence of estrogens on the androgen metabolism in different subunits of human hair follicles

The molecular pathways involved in estrogen-mediated induction of hair growth in androgenetic alopecia are unknown. Some authors found that estradiol (E) inhibited 5alpha-reductase (5alpha-R) activity and therefore we addressed the question whether 17alpha- or 17beta-E are able to modulate the activity of 5alpha-R, 3beta-hydroxysteroid dehydrogenase (3beta-HSD) or 17beta-hydroxysteroid dehydrogenase (17beta-HSD) in isolated compartments of human hair follicles. For this purpose, scalp biopsies from volunteers were taken and from each biopsy root sheaths, connective tissue sheaths and dermal papillae (DP) were dissected and incubated in the presence of 3H-testosterone (T) and, in addition, either 17alpha-E, 17beta-E, progesterone or finasteride for up to 48 hrs. Thereafter high-performance liquid chromatography analysis of culture supernatants was performed to detect T-metabolites. At the tested concentrations, finasteride was found to be a major inhibitor of dihydrotestosterone (DHT) formation. Even 1 nM finasteride inhibited DHT synthesis in DP by 86% and 1 nM progesterone by 75%. Estrogens were less able to inhibit the synthesis of DHT in DP (e.g. 100 nM 17alpha-E: 20%; 100 nM 17beta-E: 60%). Whether E directly inhibits 5alpha-R in DP's or whether the effect of estrogens might be explained by an increased conversion of T to the weaker androgens such as androstendione (via 17beta-HSD), androstenediol (via 3beta-HSD) or 17beta-E (via aromatase), thereby diminishing the amount of T available for the conversion to DHT, remains to be shown.

Direct effects of lithium chloride on the activities of delta 5-3 beta and 17 beta-hydroxysteroid dehydrogenase in the testis and Bidder's organ of the adult toad (Bufo melanostictus)--in vitro study

Steroidogenic key enzymes, i.e. delta 5-3 beta and 17 beta-hydroxysteroid dehydrogenase (delta 5-3 beta and 17 beta-HSD) activities, in the testis and Bidder's organ of the toad were inhibited and ascorbic acid synthesis in these organs was decreased by a wide range of lithium concentration in in vitro study. A significant inhibition was noted at a concentration of 2.0 mM, which is easily achieved in the blood during the treatment of manic patients by lithium chloride. This experiment reflected that lithium exerts a direct inhibitory effect on hydroxysteroid dehydrogenase activities in the testis and Bidder's organ--a rudimentary ovary in Bufo.

Effect of mercuric chloride on testicular activities in mice, Musculus albinus

Impaired testicular function was observed after an exposure of Swiss albino mice (30 +/- 2 g) to mercuric chloride. A sublethal chronic exposure (0.5 ppm for 21 days) resulted in regressed histological and histochemical properties of the testis. The changes observed were degenerated tunica albuginea, abnormal configurations of seminiferous tubules, deformed primary and secondary spermatocytes, hypertrophy and vacuolization in interstitial cells and Sertoli cells. The 3 beta and 17 beta hydroxy steroid dehydrogenase enzyme and the level of testosterone hormone were significantly (p < 0.001) reduced. The diameter of different spermatogenic cells were significantly (p < 0.001) reduced.

Effects of lindane on steroidogenesis and steroidogenic acute regulatory protein expression

Lindane, the gamma isomer of hexachlorocyclohexane (HCH), is one of the oldest synthetic pesticides still in use worldwide. Numerous reports have shown that this pesticide adversely affects reproductive function in animals. Although the pathogenesis of reproductive dysfunction is not yet fully understood, recent reports indicate that lindane can directly inhibit adrenal and gonadal steroidogenesis. Because Leydig cells play a pivotal role in male reproductive function through the production of testosterone, the mouse MA-10 Leydig tumor cell line was used to assess the potential effects of gamma-HCH and its isomers, alpha-HCH and delta-HCH, on steroid production, steroidogenic enzyme expression and activity, and steroidogenic acute regulatory (StAR) protein expression. StAR mediates the rate-limiting and acutely regulated step in hormone-stimulated steroidogenesis, the intramitochondrial transfer of cholesterol to the P450(scc) enzyme. Our studies demonstrate that alpha-, delta-, and gamma-HCH inhibited dibutyryl ([Bu](2)) cAMP-stimulated progesterone production in MA-10 cells in a dosage-dependent manner without affecting general protein synthesis; and protein kinase A or steroidogenic enzyme expression, activity, or both. In contrast, each of these isomers dramatically reduced (Bu)(2)cAMP-stimulated StAR protein levels. Therefore, our results are consistent with the hypothesis that alpha-, delta-, and gamma-HCH inhibited steroidogenesis by reducing StAR protein expression, an action that may contribute to the pathogenesis of lindane-induced reproductive dysfunction.

Structure-specific effects of thyroxine analogs on human liver 3 alpha-hydroxysteroid dehydrogenase

The NADP(H)-linked oxidoreductase activity of a major isozyme of human liver 3 alpha-hydroxysteroid dehydrogenase was activated 5-, 4-, and 2-fold by D-thyroxine (T(4)), L-T(4) and DL-3,3', 5'-triiodothyronine (reverse T(3)), respectively. Kinetic analysis of the activation indicated that D-T(4), L-T(4), and reverse T(3) are non-essential activators, showing binding constants of 1.5, 1.1, and 3.6 microM, respectively. Comparison of the effects of the T(4) analogs on the activities of the mutant enzymes suggests that the binding site is composed of at least Lys-270, Arg-276, and the C-terminal loop of the enzyme. L-T(3), DL-thyronine, and D-tyrosine had no effect on the enzyme, but 3,5,3',5'-tetra- and 3,5, 3'-tri-iodo thyropropionic acids were potent competitive inhibitors with K(i) values of 42 and 60 nM, respectively, with respect to the substrate. The inhibition constant was lowered upon the activation of the enzyme by D-T(4), and the inhibition by the deamino derivatives of T(4) and T(3) disappeared upon modification of the C-terminal loop of the enzyme, but not upon replacement of Lys-270 or Arg-276 with Met. These results indicate that, depending on their structures, the T(4) analogs bind differently to two distinct sites at the active center of the enzyme to produce stimulatory and inhibitory effects.

Luteolytic effects of DL111-IT in pregnant rats

The present studies were conducted to evaluate the effects of DL111-IT [3-(2-ethyl phenyl)-5-(3-methoxy phenyl)-1H-1,2,4 triazol] on ovaries of pregnant rats. Pregnant rats were i.m. treated with DL111-IT 2.5 mg kg(-1) day(-1) or camellia oleum (vehicle control) 0.2 ml/day from day 6 of pregnancy for 1, 3 or 5 days. Blood and ovaries were collected 24 h after the last injection. Ovarian fresh weight and protein contents, activities of the 3beta-hydroxysteroid dehydrogenase (3beta-HSD) and 20alpha-hydroxysteroid dehydrogenase (20alpha-HSD) in ovaries, and cell apoptosis of corpus luteum (including hematoxylin-eosine stain, in situ 3'-end labeling and nucleosomal banding) were estimated. Compared with that in the control group, ovarian fresh weight declined 11% and 22% after DL111-IT-3 days and -5 days; protein content dropped 29% after 5-day administration. DL111-IT for 3 days provoked a marked decrease of serum progesterone, by 31% of the control; the activity of 3beta-HSD decreased 34.4% after i.m. DL111-IT for 5 days, while that of 20alpha-HSD increased dramatically after only one injection of DL111-IT (P < 0.01). Histological analysis and in situ 3'-end DNA labeling indicated that DL111-IT induced the pyknosis of cells and the formations of apoptotic bodies and intense oligonucleosomes in luteal cells of pregnant rats. The cell apoptosis induced by DL111-IT was further confirmed by evaluation of nucleosomal DNA fragmentation by agarose gel electrophoresis in cultured luteal cells exposed to DL111-IT for 24 h. In conclusion, all results, including shrunken luteal cells, decreased concentration of protein content and serum progesterone, changed activities of 3beta-HSD and 20alpha-HSD and formation of DNA fragments in luteal cells, showed the luteolytic effect of DL111-IT in pregnant rats.

[Steroidogenesis in rat testes in chronic alcoholic intoxication and addition of ethanol in vitro]

The influence of ethanol on steroid biosynthesis in microsomal fraction of rat testes has been studied. Addition of ethanol in vitro as well as chronic alcoholization have been shown to change the activity of enzymatic ensembles of steroidogenesis in testes. A significant decrease in 3 beta-hydroxysteroid dehydrogenase activity, revealed in all experiments, has permitted the authors to conclude that this phenomenon is of special significance for the realization of gonads hormonal response to ethanol.

Oocyte-secreted factors regulate granulosa cell steroidogenesis

Investigations of strains of mice defective in germ cell development have revealed the importance of oocytes for the initial stages of folliculogenesis (Pellaset al., 1991; Huanget al., 1993). Various aspects of follicular development are dependent upon and/or influenced by the presence of oocytes, including granulosa cell proliferation (Vanderhydenet al., 1990, 1992) and cumulus expansion (Buccioneet al., 1990; Salustriet al., 1990; Vanderhydenet al., 1990; Vanderhyden, 1993). We are investigating the possibility that oocytes influence one of the primary functions of granulosa cells: steroidogenesis. In many species, granulosa cells removed from preovulatory follicles luteinisein vitro(Channinget al., 1982), presumably due to loss of contact with follicular luteinisation inhibitory factor(s). Indeed, follicular fluid can prevent granulosa cell luteinisationin vitro(Ledwitz-Rigbyet al., 1977). Follicular fluid, however, may simply be the medium for transport of factors secreted by oocytes to regulate granulosa cell activities.

The expression of steroidogenic enzyme genes in human vascular cells

Recently, we demonstrated that aldosterone is produced by human vascular cells, and that vascular aldosterone is linked to angiotensin II-induced hypertrophy of vascular smooth muscle cells. We therefore examined whether genes encoding steroidogenic enzymes responsible for aldosterone biosynthesis from cholesterol are expressed in vascular cells. Using polymerase chain reaction after reverse transcription, type I and II 3 beta-HSD (3 beta-hydroxysteroid dehydrogenase), P-450c21 (21-hydroxylase), and P-450c18 (18-hydroxylase/oxidase) genes were found to be expressed both in endothelial cells and smooth muscle cells cultivated from human pulmonary arteries. However, P-450scc (cholesterol side chain cleavage enzyme) and P-45011 beta (11 beta-hydroxylase) mRNAs could not be detected. These findings suggest that the enzyme system responsible for aldosterone production in human vascular cells is different from that found in the adrenal cortex and that vascular aldosterone may be synthesized from metabolic intermediates which originate from the circulation. Extra-adrenal 3 beta-HSD and steroid 21-hydroxylase occur in a wide variety of tissues. Thus, human vascular cells can retain the ability to produce aldosterone by expressing the P-450c18 gene.

Effect of a diphenylethylenediamine platinum complex on steroidogenesis in rats

Although less cytotoxic, the new platinum complex [meso-1,2-bis(2,6-difluoro-4-hydroxyphenyl)-ethylenediamine]sulfatopl atinum (II) (2) is equipotent to cisplatin (1) in the oestrogen-dependent MXT mammary tumour of the mouse. As this may be due to oestrogen level-lowering properties, we compared the effect of 1 and 2 on steroidogenesis in the rat. A single dose of 1 and 2 (20 mumol/kg s.c.) decreased plasma testosterone level in male rats by 90% (1, day 3) and 80% (2, day 7). Luteinizing hormone level remained unchanged in intact and in ovariectomized rats. The activities of the following testicular enzymes were decreased (day 7): cholesterol side-chain cleavage enzyme (1: 33%; 2: 36%), 3 beta-hydroxysteroid dehydrogenase/delta 4,delta 5-isomerase (1: 31%; 2: 48%) and 17 alpha-hydroxylase/17,20-lyase (1: 21%; 2: 15%). Testicular microsomal cytochrome P450 content was also diminished (1: 60%; 2: 49%, day 7). Corticosterone level in plasma and biosynthesis in adrenal explants was not affected, indicating the selectivity of action at the gonadal level. In vitro, neither 1 nor 2 (2 and 20 microM) influenced binding of human chorionic gonadotropin to testis interstitial cells during an observation period up to 21 h. These results suggest that 1 and 2 act at the gonadal level by inhibiting the expression of the steroidogenic enzymes. They do not, however, inactivate the luteinizing hormone receptor.

Decreased 3 alpha-hydroxysteroid dehydrogenase activity in peripheral blood lymphocytes from patients with primary open angle glaucoma

The purpose of the present study was to determine whether peripheral blood lymphocytes (PBL) from primary open angle glaucoma (POAG) patients have reduced 3 alpha-hydroxysteroid dehydrogenase (3 alpha-HSD) activity as was previously found in POAG-derived cultured trabecular meshwork cells. The availability of PBL from both POAG and control patients makes this a useful system for studying the association of decreased 3 alpha-HSD activity with POAG. PBL were isolated from the venous blood of 17 POAG patients and 22 non-glaucoma controls and assayed for 3 alpha-HSD activity with tritiated 5 beta-dihydrocortisol as a substrate. The mean 3 alpha-HSD activity +/- S.E.M., expressed in comparable units of specific activity, of the POAG derived PBL was 13.8 +/- 1.3 U as compared to 32.8 +/- 2.0 U for control cells. This reduction (> 50%) was statistically significant (P < 0.001). Quantitative immunoblot analysis of PBL indicated that the POAG and control cells, despite their difference in 3 alpha-HSD activity, had nearly identical amounts of 3 alpha-HSD protein. The molecular weight of PBL 3 alpha-HSD from both groups of patients was 38,000, the same as previously reported for human liver. The results of this study show an association of decreased PBL 3 alpha-HSD activity and POAG which was not related to antiglaucoma therapy. The reduced levels of 3 alpha-HSD activity in the readily obtainable PBL may serve as a marker for POAG or those at risk for developing the disease.

Activation of human liver 3 alpha-hydroxysteroid dehydrogenase by sulphobromophthalein

Human liver contains at least two isoenzymes (DD2 and DD4) of 3 alpha-hydroxysteroid/dihydrodiol dehydrogenase. The NADP(H)-linked oxidoreductase activities of DD4 were activated more than 4-fold by sulphobromophthalein at concentrations above 20 microM and under physiological pH conditions. Sulphobromophthalein did not stimulate the activities of DD2 and human liver aldehyde reductase, which are functionally and/or structurally related to DD4. No stimulatory effect on the activity of DD4 was observed with other organic anions such as Indocyanine Green, haematin and Rose Bengal. The binding of sulphobromophthalein to DD4 was instantaneous and reversible, and was detected by fluorescence and ultrafiltration assays. The activation by sulphobromophthalein decreased the activation energy in the dehydrogenation reaction for the enzyme, and increased both kcat, and Km values for the coenzymes and substrates. Kinetic analyses with respect to concentrations of NADP+ and (S)-(+)-indan-1-ol indicated that sulphobromophthalein was a non-essential activator of mixed type showing a dissociation constant of 2.6 microM. Thus, the human 3 alpha-hydroxysteroid dehydrogenase isoenzyme has a binding site specific to sulphobromophthalein, and the hepatic metabolism mediated by this isoenzyme may be influenced when this drug is administered.

Comparative effects of selective cyclooxygenase 1 and cyclooxygenase 2 inhibitors on myeloperoxidase and 3 alpha-hydroxysteroid dehydrogenase

The clinical efficacy of non-steroidal anti-inflammatory drugs (NSAIDs) is believed to result from the ability of these compounds to inhibit the inducible isoform of the enzyme cyclooxygenase, COX2. The gastrointestinal and renal side effects of these drugs, in contrast, are thought to relate to their ability to inhibit the constitutive isozyme, COX1. There is structural and pharmacological evidence that suggests that NSAIDs may also inhibit two unrelated enzymes, myeloperoxidase (MP) and 3 alpha-hydroxysteroid dehydrogenase (3 alpha-HSD), potentially with untoward consequences for the patient. Our laboratories have been investigating a new structural class of potential COX inhibitors, the tri-cyclic aromatics. In this study we have examined the inhibitory potency of selected compounds for the enzymes human COX1, human COX2, human MP, and rat liver 3 alpha-HSD. The compounds selected span a range of COX isoform selectivities, from specific for COX2 to selective for COX1 only, and include three representative tri-cyclic aromatics. We found that compounds within the tri-cyclic aromatic class do not act as potent inhibitors of either myeloperoxidase or 3 alpha-HSD. These results demonstrate the unique inhibitor selectivity that can be achieved with the tri-cyclic aromatics. Examples of COX1 selective, and COX2 selective inhibitors within this structural class are presented.

Regulation of rat hepatic 3 alpha-hydroxysteroid dehydrogenase in vivo and in primary cultures of rat hepatocytes

In the bile acid biosynthetic pathways of humans and the rat, hepatic 3 alpha-hydroxysteroid dehydrogenase (3 alpha-HSDH) catalyzes the stereospecific reduction of the 3-oxo group of bile acid precursors. In addition, 3 alpha-HSDH may serve to shuttle bile acids from sinusoidal to apical (cannalicular) membranes of the rat hepatocyte. The objective of the present study was to define the molecular regulation of rat hepatic 3 alpha-HSDH in response to the key effectors of cholesterol 7 alpha-hydroxylase, the rate-determining enzyme in bile acid biosynthesis. Steady-state 3 alpha-HSDH mRNA levels in primary cultures of rat hepatocytes fell to 16 +/- 1% of whole liver levels after 72 h in culture, indicating that the gene is not spontaneously expressed in isolated hepatocytes. However, the addition of thyroxine (1.0 microM) or dexamethasone (1.0 microM) to the culture medium resulted in steady-state mRNA levels of 34 +/- 4% and 102 +/- 20% of whole liver levels, respectively. Moreover, the combination of thyroxine and dexamethasone (each 1.0 microM) induced mRNA to levels 2-fold higher than whole liver. 3 alpha-HSDH specific activity in cultured hepatocyte cytosol increased from 3.0 +/- 0.7 to 10.4 +/- 1.3 nmol/min per mg protein in no-addition and thyroxine plus dexamethasone-treated cultures, respectively; protein mass underwent similar changes. Whole liver 3 alpha-HSDH mRNA levels decreased in thyroidectomized, adrenalectomized, and hypophysectomized rats, to 60 +/- 6%, 51 +/- 4%, and 29 +/- 5% of sham-operated rats, respectively.(ABSTRACT TRUNCATED AT 250 WORDS)

Regulation by dexamethasone of the 3 beta-hydroxysteroid dehydrogenase activity in adult rat Leydig cells

The effect of long-term in vitro treatment with dexamethasone, insulin and/or LH on the 3 beta-hydroxysteroid dehydrogenase (3 beta-HSD) activity and the testosterone level was examined in cultures of Leydig cells from adult rats. A rapid and simple method for measuring the 3 beta-HSD activity has been developed, in which the NADH, generated by 3 beta-HSD, reduced nitroblue tetrazolium to a product with absorption maximum at 560 nm. Km for the reaction was 8.1 microM and Vmax was 12.7 nmol/min x mg protein. Addition of 0.1 or 1 microM dexamethasone for 44 h decreased the 3 beta-HSD activity to 83% and the basal testosterone level to 64% of control value after 22 and 44 h of culture. Addition of 1 nM insulin inhibited the 3 beta-HSD activity to 90% after 44 h of culture, whereas the testosterone level was increased after 3 h. Addition of 0.1 ng/ml LH did not affect the 3 beta-HSD activity in Leydig cells from adult rats. Concomitant treatment of the cells with dexamethasone and insulin inhibited the 3 beta-HSD activity to 74%, indicating an additive effect, whereas no additive effect on the testosterone level was observed. The results demonstrate that the 3 beta-HSD activity can be measured in a rapid and reliable way by measuring the reduction of nitroblue tetrazolium. Furthermore, the results suggest that dexamethasone acts on 3 beta-HSD through a mechanism different from that of insulin, as an additive effect was observed.

[The morphofunctional characteristics of the adrenal cortical substance after exposure to an adrenocorticolytic agent]

The administration of dioxidine to 1-month-old rats (200 mg/kg i.p.) results in destructive alterations of adrenocorticocytes, damage of their mitochondria, dramatic reduction of activity of succinic- and 3 beta-ol-steroid dehydrogenases. The abolition of the drug is followed within 6, 12, 30 days by progress of alternative changes, inhibition of growth of the adrenals which results 30 days later in atrophy of the whole gland and the cortical substance.