Gonadal toxicity of short term chronic endosulfan exposure to male rats

Endosulfan was studied for its effect on rat testicular toxicity in relation to the enzymes of androgen biosynthesis, viz. 3 beta-hydroxysteroid dehydrogenase (EC 1.1.1.145, 3 beta-HSD) and 17 beta-hydroxysteroid dehydrogenase (EC 1.1.1.64, 17 beta-HSD); cytosolic conjugation enzyme, glutathione-S-transferase (EC 2.5.1.18); and testicular as well as serum testosterone levels at the dose levels of 2.5, 5.0, 7.5 and 10 mg/kg body weight fed orally for 7 and 15 days. Organ and body weights of the treated animals did not change significantly, however, the testicular protein contents were found to be increased appreciably after 7 days treatments. The activity profile of cytosolic conjugation enzyme showed much remained low during 7 days treatment, however, the two steroidogenic enzymes showed much individual variations in response to endosulfan treatments. An overall varied response with respect to testosterone biosynthesis and its secretion to serum was observed suggesting nevertheless, a profound hormonal imbalance caused by this insecticide to male gonads on short term chronic exposures.     

Effects of gold on testicular steroidogenic and gametogenic functions in immature male albino rats

The present study was undertaken to evaluate the effects of gold chloride, a metallic earth salt, on steroidogenic and gametogenic functions of testis in immature rats. Immature rats of Wistar strain, were injected (s.c.) with gold chloride at the dose of 0.3 mg and 0.5 mg/kg body weight/day for 26 days. All the treated animals along with the vehicle-treated controls were sacrificed 24 hours after last injections. Testicular steroidogenic activity was evaluated by measuring the activities of two steroidogenic key enzymes, Delta5-3beta-hydroxysteroid dehydrogenase (Delta5-3beta-HSD) and 17-beta hydroxysteroid dehydrogenase (17-beta HSD). Gametogenic capacity was determined by counting the number of germ cells at stage VII of seminiferous cycle. Plasma levels of testosterone (T) was measured by radioimmunoassay (RIA). Administration of gold chloride at a dose of 0.3 mg/ kg body weight for 26 days led to insignificant changes of testicular Delta5-3beta-HSD,17beta-HSD activities and gametogenesis along with plasma T. In contrast 0.5 mg gold chloride treatment for 26 days caused a significant increase in plasma T (p < 0.001) along with stimulation of testicular Delta5-3beta-HSD activity (p < 0.001) and 17beta-HSD activity (p < 0.001). Gametogenic activity exhibited a significant increase in the number of step 7 spermatids (7Sd) (p < 0.001) at stage VII of seminiferous cycle when compared to control. The results of our experiment suggest that gold chloride treatment might be associated with significant stimulatory effects on testicular activities. Furthermore, since hormonal changes, altered steroidogenic enzymes and gametogenic activities were evident to a specific dose of gold chloride treatment, our data may have some clinical implication on the stimulation of fertility.     

Chronic administration of corticosterone impairs LH signal transduction and steroidogenesis in rat Leydig cells

The mechanism involved in the inhibitory actions of chronic corticosterone treatment on Leydig cell steroidogenesis was studied in adult Wistar rats. Rats were treated with corticosterone-21-acetate (2 mg/100 g body weight, i.m., twice daily) for 15 days and another set of rats was treated with corticosterone plus ovine luteinizing hormone (oLH) (100 microg/kg body weight, s.c., daily) for 15 days. Chronic treatment with corticosterone increased serum corticosterone but decreased serum LH, testosterone, estradiol and testicular interstitial fluid (TIF) testosterone and estradiol concentrations. Administration of LH with corticosterone partially prevented the decrease in serum and TIF testosterone and estradiol. Leydig cell LH receptor number, basal and LH-stimulated cAMP production were diminished by corticosterone treatment which remained at control level in the corticosterone plus LH treated rats. Activities of steroidogenic enzymes, 3beta- and 17beta-hydroxysteroid dehydrogenase (3beta-HSD and 17beta-HSD) were significantly decreased in corticosterone treated rats. LH plus corticosterone treatment did not affect 3beta-HSD activity but decreased 17beta-HSD activity, indicating a direct inhibitory effect of excess corticosterone on Leydig cell testosterone synthesis. The indirect effect of corticosterone, thus, assume to be mediated through lower LH which regulates the activity of 3beta-HSD. Basal, LH and cAMP-stimulated testosterone production by Leydig cells of corticosterone and corticosterone plus LH treated rats were decreased compared to control suggesting the deleterious effect of excess corticosterone on LH signal transduction and thus steroidogenesis.     

Multiple mechanisms of ethanol-induced gonadal toxicity to adult male rats.

In an attempt to elucidate the mechanism(s) underlying the alcohol-induced pathogenesis of testis, acute as well as chronic studies were undertaken in adult male rats. Ethanol reduced significantly the plasma and testicular testosterone contents in treated rats even at moderate dose levels. The alterations in pituitary gonadotrophins, LH and FSH, demonstrated a central defect in the hypothalamo-hypophyseal-gonadal axis. Major microsomal enzymes involved in the biosynthesis of testosterone, viz. 3 beta-hydroxysteroid dehydrogenase and steroidogenic mixed function oxidases were markedly inhibited in a dose and duration dependent manner. The terminal enzyme 17 beta-hydroxysteroid dehydrogenase was, however, unaffected by ethanol treatments except at a higher dose level of 6 g/kg body wt. Although, the activity of testicular alcohol dehydrogenase was relatively unchanged, a marked induction in the activity of cytosolic conjugation enzyme, GSH-s-transferase was noticed. The present study demonstrates the major role of the metabolism of ethanol in the underlying cause for in vivo toxicity of ethanol and warrants its further consideration.     

Inhibitory effects of stress-activated nitric oxide on antioxidant enzymes and testicular steroidogenesis

The messenger role of nitric oxide (NO) in immobilization stress-induced inhibition of testicular steroidogenesis has been previously suggested. In accord with this, here, we show that the intratesticular injection of isosorbide dinitrate (ISDN; 2x2.5 mg/testis), an NO donor, mimicked the action of stress on serum testosterone concentrations and hCG-stimulated testosterone production in rat testicular tissue. When added in vitro, ISDN inhibited testicular 3beta-hydroxysteroid dehydrogenase and 17alpha-hydroxylase/lyase. Immobilization stress and injections of ISDN also decreased the activity of catalase, glutathione peroxidase, glutathione transferase, and glutathione reductase in the interstitial compartment of testis. When stressed rats were treated concomitantly with bilateral intratesticular injections of N(omega)-nitro-L-arginine methyl ester, a non-selective NOS inhibitor (2x600 microg/testis), the activities of antioxidative enzymes, as well as serum testosterone concentration, were partially normalized. These results indicate that stress-induced stimulation of the testicular NO signalling pathway leads to inhibition of both steroidogenic and antioxidant enzymes.     

Effect of sub-chronic endosulfan exposures on plasma gonadotrophins, testosterone, testicular testosterone and enzymes of androgen biosynthesis in rat

Insecticide endosulfan significantly inhibited testicular androgen biosynthesis in adult rats, when fed (po) at 7.5 and 10 mg/kg body weight dose levels, consecutively for 15 and 30 days. No appreciable alterations were apparent in body weights, testicular wet weights, and cytosolic and microsomal protein contents of testis in treated rats. Profound decrease in the levels of plasma gonadotrophins (FSH and LH) along with plasma testosterone and testicular testosterone were observed at both the doses of endosulfan, particularly after the longer exposure of 30 days. Activities of steroidogenic enzymes studied (3 beta- and 17 beta-hydroxysteroid dehydrogenases) were considerably lowered on longer exposure of endosulfan. A significant decrease in the contents/activities of microsomal cytochrome P-450 and related mixed function oxidases (MFOs) in testis of treated rats was also observed, along with a marked inhibition in the activity of cytosolic conjugation enzyme, glutathione-S-transferase at both doses studied. These biochemical changes were reversed when the endosulfan treatment was withdrawn.     

Chronic corticosterone treatment impairs Leydig cell 11beta-hydroxysteroid dehydrogenase activity and LH-stimulated testosterone production.

The effects of excess corticosterone on luteinizing hormone (LH)-stimulated Leydig cell testosterone production and activity of 11beta-HSD was studied. Adult male rats (200-250 g body weight) were treated with corticosterone-21-acetate (2 mg/100 g body weight, i.m., twice daily) for 15 days. Another set of rats was treated with corticosterone (dose as above) plus LH (ovine LH 100 microg/kg body weight, s.c., daily) for 15 days. Corticosterone administration significantly increased serum and testicular interstitial fluid (TIF) corticosterone but decreased testosterone levels. Administration of LH with corticosterone partially prevented the decrease in serum and TIF testosterone. The oxidative activity of 11beta-hydroxysteroid dehydrogenase (11beta-HSD) was significantly decreased in Leydig cells of rats treated with corticosterone alone and in combination with LH. The direct effect of corticosterone on Leydig cell steroidogenic potency was also studied in vitro. Addition of corticosterone to Leydig cell culture showed a dose dependent effect on LH-stimulated testosterone production. Corticosterone at 50 and 100 ng/ml did not alter LH-stimulated testosterone production, but at high doses (200-400 ng/ml), decreased basal and LH-stimulated testosterone production. Basal and LH-stimulated cAMP production was not altered by corticosterone in vitro. It is concluded from the present study that elevated levels of corticosterone decreased the oxidative activity of 11beta-HSD and thus resulting in impaired Leydig cell steroidogenesis and the inhibitory effects of corticosterone on testosterone production appear to be mediated through inhibition of LH signal transduction at post-cAMP level.     

Effect of lithium chloride on spermatogenesis and testicular delta 5-3 beta, 17 beta-hydroxysteroid dehydrogenase activities in the 'antiserum to luteinizing hormone' treated toad (Bufo melanostictus)

Activities of delta 5-3 beta- and 17 beta-hydroxysteroid dehydrogenase (delta 5-3 beta-HSD and 17 beta-HSD), Leydig cell nuclear area (LCNA) and spermatogenesis in the testis were observed after injection of lithium chloride in the 'antiserum to luteinizing hormone (LH)' treated toad. A significant decrease in the activities of steroidogenic enzymes, LCNA and spermatogenesis were noticed after the injections of 'antiserum to LH' to toads. Further decrease in the activities of the above parameters was observed in the lithium chloride--'antiserum to LH' treated toad. It is suggested that lithium chloride may inhibits testicular function without modulating the pituitary activity.     

Effect of 5-thio-D-glucose on testosterone biosynthesis in vivo in mice testes

Testicular synthesis of (14C)cholesterol and (14C)testosterone from (14C)acetate were investigated in mice treated with 5-thio-D-glucose at a dose of 33 mg/kg body weight/day for 21 days. The testicular synthesis of free cholesterol as well as steroids were significantly decreased. The steroid synthesizing enzymes, cholesterol esterase, cholesterol side-chain cleaving enzyme, total alpha-hydroxysteroid dehydrogenase and total beta-hydroxysteroid dehydrogenase, were also analysed. Cholesterol esterase and total beta-hydroxysteroid dehydrogenase were significantly reduced whereas total alpha-hydroxysteroid dehydrogenase was unaffected. Hence, a decrease in free cholesterol for steroid synthesis and a decreased activity of the steroidogenic enzyme, beta-hydroxysteroid dehydrogenase, were responsible for the diminished synthesis of testosterone.     

Evaluation of single intratesticular injection of calcium chloride for nonsurgical sterilization of male Black Bengal goats (Capra hircus): a dose-dependent study

This study describes the induction of chemosterilization in three groups each of six adult male Black Bengal goats at 30 days after a single bilateral intratesticular injection of a calcium chloride (CaCl(2), 2H(2)O) solution at the doses of 10, 20 or 40 mg/kg body weight/testis, always in a 2 ml volume of normal saline. Another one group of animals received only 2 ml of normal saline per testis as a control. The induction of chemosterilization was measured using relative testicular weight as well as histomorphological parameters including seminiferous tubular architecture and germ cell association in seminiferous tubules along with morphology of the interstitial space. Biochemical markers included activities of testicular Delta(5), 3beta-hydroxysteroid dehydrogenase (Delta(5), 3beta-HSD), 17beta-hydroxysteroid dehydrogenase (17beta-HSD), catalase, glutathione peroxidase (GPx), glutathione S-transferase (GST) and superoxide dismutase (SOD) as well as monitoring the level of testicular thiobarbituric acid reactive substances (TBARS), conjugated dienes and reduced glutathione (GSH) content along with plasma concentrations of testosterone, LH and FSH. Histomorphological measures of testes showed total necrosis of testicular tissue at 30 days after an injection of either 20 or 40 mg CaCl(2) along with fibrosis in seminiferous tubules and interstitial spaces. Infiltration of leucocytes was observed with the 40 mg dose. Disintegration of germ cell arrangement in seminiferous tubules and washing out of germ cells from the tubules were noted with the 10mg dose. Relative organ weights, plasma concentrations of testosterone, testicular activities of Delta(5), 3beta-HSD, 17beta-HSD, catalase, GPx, GST, and SOD and testicular contents of GSH all were declined. Increases occurred in testicular TBARS, conjugated dienes and plasma concentrations of LH and FSH with each of the treatments by comparison with the control group. Plasma concentrations of cortisol and fasting blood sugar level as well as packed cell volume (PCV) and total plasma protein were recorded to monitor the changes of chronic stress in the experimental animals. Changes in these parameters were not significant. An intratesticular injection of calcium chloride at specified doses could be a suitable method of sterilization in preference to surgical castration of goats.     

Effects of tri-iodothyronine on testicular interstitial cells and androgen secretory capacity of the prepubertal Rat

The main objective of the study was to investigate the effects of hyperthyroidism on the rat testis interstitium during prepuberty, which is not well understood at present. Male Sprague Dawley rats were injected subcutaneously daily with saline (controls) or tri-iodothyronine (T(3), 50 microg/kg body weight; hyperthyroids) from postnatal Day 1. Rats were killed at Days 5, 7, 9, 12, 16, and 21. One testis of each rat was used to determine LH-stimulated (100 ng/ml) testicular androgen secretory capacity in vitro. The other testis was used either for morphometric studies (n = 5) or for immunolocalization of 3 beta-hydroxysteroid dehydrogenase (3 beta-HSD) to identify steroidogenic cells (n = 3) and 11 beta-hydroxysteroid dehydrogenase 1 (11 beta-HSD1) to differentially identify adult Leydig cells. Daily T(3) injections resulted in significant reductions in body and testis weights. Morphometric analysis revealed that lower testis weights in rats treated with T(3) were mainly the result of reductions of total volume of seminiferous cords/tubules. The number of interstitial mesenchymal cells (MCs) was lower (P < 0.05) in T(3) rats compared with age-matched controls. The number of fetal Leydig cells (FLCs) was not different between the two groups; however, FLC hypotrophy was detected in T(3) rats at Day 16 in contrast to Day 21 in control rats. In both groups, morphologically identifiable adult Leydig cells (ALCs) were observed at Day 12 and thereafter; however, the ALC number per testis in T(3) rats was twice as much as those of controls. Positive immunolabeling for 3beta-HSD was first detected in MC/progenitor cells on Day 9 in rats in the T(3) group (cells were still spindle-shaped) and on Day 12 in rats in the control group. Testicular testosterone production in vitro was lower (P < 0.05) in T(3) rats compared with controls at each age tested and further reductions (<0.05) were observed in T(3) rats at Days 16 and 21. Testicular androstenedione production was also lower (P < 0.05) in T(3) rats at Days 5 and 7, but increased (P < 0.05) thereafter, than in control rats. These findings support that there are more newly formed ALCs in T(3) testes than in those of controls. Moreover, these results demonstrate that hyperthyroidism stimulates premature hypotrophy of FLCs and early differentiation of increased numbers of MCs to ALCs in the prepubertal rat testis, further supporting the view that thyroid hormone has a regulatory role in initiating MC differentiation into ALCs in the prepubertal rat testis.     

Expression of steroidogenic enzymes and synthesis of sex steroid hormones from DHEA in skeletal muscle of rats

The functional importance of sex steroid hormones (testosterone and estrogens), derived from extragonadal tissues, has recently gained significant appreciation. Circulating dehydroepiandrosterone (DHEA) is peripherally taken up and converted to testosterone by 3beta-hydroxysteroid dehydrogenase (HSD) and 17beta-HSD, and testosterone in turn is irreversibly converted to estrogens by aromatase cytochrome P-450 (P450arom). Although sex steroid hormones have been implicated in skeletal muscle regulation and adaptation, it is unclear whether skeletal muscles have a local steroidogenic enzymatic machinery capable of metabolizing circulating DHEA. Thus, here, we investigate whether the three key steroidogenic enzymes (3beta-HSD, 17beta-HSD, and P450arom) are present in the skeletal muscle and are capable of generating sex steroid hormones. Consistent with our hypothesis, the present study demonstrates mRNA and protein expression of these enzymes in the skeletal muscle cells of rats both in vivo and in culture (in vitro). Importantly, we also show an intracellular formation of testosterone and estradiol from DHEA or testosterone in cultured muscle cells in a dose-dependent manner. These findings are novel and important in that they provide the first evidence showing that skeletal muscles are capable of locally synthesizing sex steroid hormones from circulating DHEA or testosterone.     

The effects of temperature on the activity of testicular steroidogenic enzymes

Decreased sperm counts and impaired sperm motility are present in a substantial proportion of men with varicocele. Elevations in the temperature of the affected testis, and increased spermatic vein estradiol (E2) concentrations have been found in some of these patients. To investigate the possibility that increases in temperature lead to a pattern of testicular steroidogenesis that results in increased E2 synthesis, we have examined the effects of temperature changes on the activities of four important testicular steroidogenic enzymes. 3 beta-hydroxysteroid dehydrogenase (3 beta-HSD), 17-hydroxylase (17-OH), 17,20-desmolase (17,20-D) and aromatase activities were measured in the microsomal fraction of rat, pig and horse testes. Incubations were performed at 34 degrees C, 36 degrees C, and 38 degrees C. The activities of all 4 enzymes increased with each 2 degrees C temperature elevation in roughly proportional amounts. We conclude that minor elevations in incubation temperature are associated with increases in the in vitro activity of four key testicular steroidogenic enzymes.     

Effects of lithium chloride on testicular steroidogenic and gametogenic functions in mature male albino rats

The present study was undertaken to evaluate the effects of lithium, an antimanic drug, on steroidogenic and gametogenic functions of testis in the laboratory rat. Adult male rats of Wistar strain maintained under standard laboratory conditions (L:D, 14h:10h), were injected (S.C) with lithium chloride at the dose of 0.1 mg, 0.2 mg and 0.4 mg/100 g body weight/day for 21 days. All the treated animals along with the vehicle treated controls were sacrificed 24 hours after the last injections. Testicular steroidogenic activity was evaluated by measuring the activities of two steroidogenic key enzymes, delta 5-3 beta hydroxysteroid dehydrogenase (delta 5-3 beta-HSD) and 17 beta hydroxysteroid dehydrogenase (17 beta-HSD). Gametogenic capacity was determined by counting the number of germ cells at stage VII of seminiferous cycle. Plasma levels of follicle stimulating hormone (FSH), luteinizing hormone (LH), prolactin (PRL) and testosterone (T) were measured by radioimmunoassay (RIA). Administration of lithium chloride at a dose of 0.1 mg/100 g body wt. for 21 days led to insignificant changes of plasma FSH, LH, PRL and T along with unaltered activities of testicular delta 5-3 beta-HSD, 17 beta-HSD activities and gametogenesis. In contrast, 0.2 mg of lithium treatment for 21 days causes a significant reduction of plasma FSH (P less than 0.01), LH (P less than 0.001), PRL (P less than 0.001) and T (P less than 0.001) along with inhibition of testicular delta 5-3 beta-HSD activity (P less than 0.01) and 17 beta-HSD activity (P less than 0.001). Gametogenic activity does not exhibits any significant reduction in the number of preleptotene spermatocytes (PLSc) and midpachytene spermatocytes (mPSC) while significant reduction in the number of spermatogonia A (Asg) (P less than 0.01) and Step 7 spermatids (7Sd) (P less than 0.001) were observed at stage VII of seminiferous cycle when compared to control. The degree of detrimental effects of lithium on testicular activity became more prominent at the dose of 0.4 mg/100 g body wt. The results of our experiments suggest that lithium administration might be associated with significant adverse effects on testicular activities. Furthermore, since hormonal changes and altered gametogenic activities were evident when plasma lithium concentration was below or within the therapeutic range, our data may have some potential clinical implications.     

Morphofunctional alterations in testicular cells of deslorelin-treated boars: an immunohistochemical study

In this study we thoroughly scrutinized testes morphology and investigated whether treatment of recipient boars with gonadotropin-releasing hormone (GnRH)-agonist deslorelin could alter the expression of 3beta-hydroxysteroid dehydrogenase (3beta-HSD), luteinizing hormone receptors (LHRs), and androgen receptors (ARs) in testicular cells. An implant containing 4.7 mg of the GnRH-agonist deslorelin was subcutaneously inserted into crossbred male pigs at 91 and 147 days of age. Testicular traits, morphology of the testes, the proteins' expression, and testosterone concentration in blood plasma were analyzed in all boars after slaughter at 175 days of age. Histological analysis revealed significant alterations in both the interstitial tissue and seminiferous tubules of experimental animals after 28 and 84 days of deslorelin treatment. The intensity of the AR immunostaining within the testis appeared as a function of the severity of testicular dysgenesis. Time-dependent action of deslorelin on the expression of LHR and 3beta-HSD in Leydig cells was also detected. Staining for LHR and 3beta-HSD was very weak or the Leydig cells were immunonegative. Concomitantly, a significant decrease in plasma testosterone level was found in both groups of deslorelin-treated boars when compared with the control group. This is the first report showing the cellular distribution of AR, LHR, and 3beta-HSD in testicular cells of deslorelin-treated boars. It is concluded that morphological and immunohistochemical studies are important for the evaluation of testicular histoarchitecture and steroidogenic function. Subsequently, the endocrine control of reproduction in the GnRH-agonist deslorelin-treated males will be better understood.     

Involvement of dietary glucose in adrenal steroidal regulation of spermatogenic and steroidogenic activities in prepubertal rat testis.

Effects of dietary and supplemented dextrose energy on the role of corticosterone (Comp. B) or dehydroepiandrosterone (DHA) in spermatogenic and steroidogenic activity in the bilaterally adrenalectomised prepubertal rat testis were studied. Adrenalectomy reduced the body and testis weight, numbers of the stage VII cell types [spermatogonia A (A), preleptotene (PL) and pachytene (P) spermatocytes and step 7 spermatid (7)], testicular delta 5-3 beta-hydroxysteroid dehydrogenase (delta 5-3 beta-OH-SDH) activity and serum testosterone. Adrenalectomy also caused reduction of energy intake due to loss of appetite which was stimulated by hormone replacement therapy. Treatment of adrenalectomised rats with DNA or corticosterone enhanced the spermatocyte population and the enzyme activity, especially after 30 days of age. Dextrose supplementation with hormone treatment however, did not produce significant additive effect on stage VII cell counts, but delta 5-3 beta-OH-SDH activity showed additive effect in this age group. Results suggest that adrenal steroids regulate testicular steroidogenesis and spermatogenesis during the prepubertal ages by modifying the supply of dietary glucose.     

Effect of Physalis peruviana L. on Cadmium-Induced Testicular Toxicity in Rats

Cadmium (Cd) stimulates the production of reactive oxygen species and causes tissue damage. We investigated here the protective effect of Physalis peruviana L. (family Solanaceae) against cadmium-induced testes toxicity in rats. Twenty-eight Wistar albino rats were used. They were divided into four groups (n?=?7). Group 1 was used as control. Group 2 was intraperitoneally injected with 6.5 mg/kg body weight (bwt) of cadmium chloride for 5 days. Group 3 was orally treated with 200 mg/kg bwt of methanolic extract of physalis (MEPh). Group 4 was pretreated with MEPh before cadmium for 5 days. Changes in body and testes weights were determined. Oxidative stress markers, antioxidant enzymes, and testosterone level were measured. Histopathological changes of testes were examined, and the immunohistochemical staining for the proapoptotic (caspase-3) protein was performed. The injection of cadmium caused a significant decrease in body weight, while a significant increase in testes weight and testes weight index was observed. Pretreatment with MEPh was associated with significant reduction in the toxic effects of Cd as shown by reduced testicular levels of malondialdehyde, nitric oxide, and caspase-3 expression and increased glutathione content, and the activities of superoxide dismutase, catalase, glutathione reductase, glutathione peroxidase, and testosterone were also increased. Testicular histopathology showed that Cd produced an extensive germ cell apoptosis, and the pretreatment of MEPh in Cd-treated rats significantly reduced Cd-induced testicular damage. On the basis of the above results, it can be hypothesized that P. peruviana L. has a protective effect against cadmium-induced testicular oxidative stress and apoptosis in the rat.     

Immunocytochemical localization of 17 beta-hydroxysteroid dehydrogenase in porcine testis

The immunocytochemical localization of 17 beta-hydroxysteroid dehydrogenase (17 beta-HSD) in porcine testes was examined by applying an indirect-immunofluorescence method using an antiporcine testicular 17 beta-HSD antibody. Only the Leydig cells located in the interstitial tissue exhibited a positive immunoreaction for 17 beta-HSD: the germ cells and Sertoli cells located in the seminiferous tubules were entirely negative. These results suggest that, in porcine testis, the biosynthesis of testicular testosterone, the final step of which is the conversion of androstenedione to testosterone, takes place in the Leydig cells.     

Role of beta-carotene in ameliorating the cadmium-induced oxidative stress in rat brain and testis

The role of oxidative stress in chronic cadmium (Cd) toxicity and its prevention by cotreatment with beta-carotene was investigated. Adult male rats were intragastrically administered 2 mg CdCl2/kg body weight three times a week intragastrically for 3 and 6 weeks. Brain and testicular thiobarbituric acid reactive substances (TBARS) was elevated after 3 and 6 weeks of Cd administration, indicating increased lipid peroxidation (LPO) and oxidative stress. Cellular damage was indicated by inhibition of adenosine triphosphatase (ATPase) activity and increased lactate dehydrogenase (LDH) activity in brain and testicular tissues. Chronic Cd administration resulted in a decline in glutathione (GSH) content and a decrease of superoxide dismutase (SOD) and glutathione S-transferase (GST) activity in both organs. Administration of beta-carotene (250 IU/kg i.g.) concurrent with Cd ameliorated Cd-induced LPO. The brain and testicular antioxidants, SOD, GST, and GSH, decreased by Cd alone, were restored by beta-carotene cotreatment. Concurrent treatment with beta-carotene also ameliorated the decrease in ATPase activity and the increase in LDH activity in brain and testis of Cd-treated rats, indicating a prophylactic action of beta-carotene on Cd toxicity. Therefore, the results indicate that the nutritional antioxidant beta-carotene ameliorated oxidative stress and the loss of cellular antioxidants and suggest that beta-carotene may control Cd-induced brain and testicular toxicity.     

Production of sex steroid hormones from DHEA in articular chondrocyte of rats

Dehydroepiandrosterone (DHEA), a precursor of sex steroid hormones, is synthesized by cholesterol side-chain cleavage cytochrome P-450 and 17alpha-hydroxylase cytochrome P-450 mainly from cholesterol and converted to testosterone and estrogen by 3beta-hydroxysteroid dehydrogenase (3beta-HSD), 17beta-HSD, and aromatase cytochrome P-450. Although sex steroid hormones have important effects in the protection of articular cartilage, it is unclear whether articular cartilage has a local steroidogenic enzymatic machinery capable of metabolizing DHEA. This study was aimed to clarify whether steroidogenesis-related enzymes are expressed in articular chondrocytes, whether expression levels are changed by DHEA, and whether articular chondrocytes are capable of synthesizing sex steroid hormones from DHEA. Articular chondrocytes isolated from adult rats were cultured with DHEA for 3 days. All of the mRNA expressions of steroidogenesis-related enzymes were detected in cultured articular chondrocytes of rats, but the mRNA expression levels of testosterone and estradiol in cultured media increased after the addition of DHEA. These findings provided the first evidence that articular chondrocytes expressed steroidogenesis-related enzyme genes and that they are capable of locally synthesizing sex steroid hormones locally from DHEA.