Nitric oxide-scavenging activity of polyhydroxylated fullerenol, C60(OH)24.

Investigation of the possible nitric oxide-scavenging activity of hydroxylated derivative of fullerene, fullerenol C60(OH)24, demonstrated that it expressed direct scavenging activity toward nitric oxide radical (NO) liberated within solution of sodium nitroprusside (SNP), a well known NO donor. In parallel, pre-treatment (30') with intratesticular injection of fullerenol (60 microg/each testis) prevented NO-induced decrease of catalase, glutathione transferase and glutathione peroxidase activities in the denucleated fraction of interstitial testicular cells of adult rats 2 h after intratesticular injection of SNP (20 microg/each testis). In addition, fullerenol decreased formation of thiobarbituric acid-reactive substances (TBA-RS) with similar efficiency as butylated hydroxy toluen (BHT), a well known antioxidant. Also, fullerenol expressed certain scavenging activity toward superoxide anion (O2-) in xanthine/xanthine oxidase system. In summary, results obtained in this study confirmed free radical-scavenging activity of fullerenol, and according to our knowledge, it is the first evidence of direct NO-quenching activity of hydroxylated C60 derivative in different milieu.     

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.     

Mechanism of Testosterone Deficiency in the Transgenic Sickle Cell Mouse

Testosterone deficiency is associated with sickle cell disease (SCD), but its underlying mechanism is not known. We investigated the possible occurrence and mechanism of testosterone deficiency in a mouse model of human SCD. Transgenic sickle male mice (Sickle) exhibited decreased serum and intratesticular testosterone and increased luteinizing hormone (LH) levels compared with wild type (WT) mice, indicating primary hypogonadism in Sickle mice. LH-, dbcAMP-, and pregnenolone- (but not 22-hydroxycholesterol)- stimulated testosterone production by Leydig cells isolated from the Sickle mouse testis was decreased compared to that of WT mice, implying defective Leydig cell steroidogenesis. There also was reduced protein expression of steroidogenic acute regulatory protein (STAR), but not cholesterol side-chain cleavage enzyme (P450scc), in the Sickle mouse testis. These data suggest that the capacity of P450scc to support testosterone production may be limited by the supply of cholesterol to the mitochondria in Sickle mice. The sickle mouse testis exhibited upregulated NADPH oxidase subunit gp91phox and increased oxidative stress, measured as 4-hydroxy-2-nonenal, and unchanged protein expression of an antioxidant glutathione peroxidase-1. Mice heterozygous for the human sickle globin (Hemi) exhibited intermediate hypogonadal changes between those of WT and Sickle mice. These results demonstrate that testosterone deficiency occurs in Sickle mice, mimicking the human condition. The defects in the Leydig cell steroidogenic pathway in Sickle mice, mainly due to reduced availability of cholesterol for testosterone production, may be related to NADPH oxidase-derived oxidative stress. Our findings suggest that targeting testicular oxidative stress or steroidogenesis mechanisms in SCD offers a potential treatment for improving phenotypic changes associated with testosterone deficiency in this disease.     

Intratesticular injection of [D-Met2-Pro5]enkephalinamide suppresses testosterone secretion of the testis of immature rat

The possible role of enkephalin in the local control of testicular function was studied in neonatal rats. 5- and 10-day old hemicastrated rats were treated intratesticularly with an enkephalin analog [D-Met2-Pro5]enkephalinamide. In 5-day-old rats local injection of different doses (0.1-0.3 micrograms/testis) of the peptide suppressed basal testosterone secretion in vitro in a dose-dependent manner 2 h posttreatment. Intratesticular administration of naloxone prior to enkephalin treatment prevented the decrease in basal testosterone production induced by the opioid agonist. In 10-day-old animals intratesticular injection of 1.0 and 3.0 micrograms/testis of enkephalinamide reduced serum testosterone concentration and basal testosterone secretion in vitro. Systemic injection of the peptide produced no change in steroidogenesis. These results suggest that enkephalins might be among the intratesticular factors regulating Leydig cell functions.     

Effects of testosterone, estradiol, aromatase inhibitor, gonadotropin and prolactin on the response of mouse testes to acute gonadotropin stimulation

These studies determined the local acute responsiveness of the testis to intratesticular administration of human chorionic gonadotropin (hCG) under basal, stimulated (systemic hCG pre-treated), hypogonadotropic (steroid pre-treatment) and hyperprolactinemic conditions in male mice. In addition, testicular testosterone (T) levels were determined after intratesticular administration of the aromatase inhibitor, 4-hydroxyandrostenedione (4-OHA) or progesterone under basal or hCG-stimulated conditions. Intratesticular administration of 0.025, 0.25, 2.5 or 25 mIU hCG resulted in a dose-dependent (3- to 14-fold) increase in testicular T concentrations in hCG compared to vehicle-injected testes. Systemic (i.p.) pre-treatment with 5 IU hCG 24 h before prevented any further increases in the already elevated (10-fold basal) T levels after direct intratesticular hCG injection. Pretreatment with 250 micrograms testosterone propionate (TP) reduced basal testicular T concentrations, but resulted in increased responsiveness to intratesticular hCG administration. In contrast, estradiol benzoate (EB) pretreatment, which also reduced basal testicular T concentrations, did not affect the testicular responsiveness to hCG. Hyperprolactinemia reduced testicular responsiveness to intratesticular administration of 0.025, 0.25 or 2.5 mIU hCG, but basal levels of testicular T were elevated. One hour after intratesticular injections of an aromatase inhibitor, 4-OHA; (0.25 micrograms) testis, T levels were increased in males pre-treated with 5 IU hCG (i.p.) 24 h earlier. Higher doses of 4-OHA (2.5, 25 or 250 micrograms) resulted in significant, dose-related increases in basal testicular T levels which were attenuated by hCG-pre-treatment. Intratesticular administration of 20 micrograms progesterone increased testicular T concentrations 2.7-fold, but this effect was attenuated (1.5-fold) in hCG-pre-treated mice, suggesting that enzymatic lesions beyond progesterone may be involved in hCG-induced testicular desensitization. These results indicate that testicular responsiveness to hCG depends on the existing levels of gonadotropic stimulation. However, it is evident that estrogens and prolactin also influence the sensitivity of the testis to gonadotropin.     

Role of ethanol metabolism in the inhibition of testosterone biosynthesis in rats in vivo: importance of gonadotropin stimulation

The mechanisms by which ethanol (EtOH, 1.5 g/kg) inhibits testicular testosterone synthesis were studied in nonstimulated and human chorionic gonadotropin (hCG, 50 IU/kg)-treated male rats. To dissociate the effects caused by ethanol metabolism, the alcohol dehydrogenase inhibitor 4-methylpyrazole (4MP, 10 mg/kg) was given to half of the rats 30 min before EtOH. The 4MP had little or no effect in the nonstimulated rats on the EtOH-induced decreases in the concentrations of serum testosterone and of the intratesticular steroids of the testosterone biosynthetic pathway measured, but reduced the EtOH-induced elevation in the intratesticular pregnenolone-to-progesterone ratio. In contrast, 4MP pretreatment markedly reversed the EtOH-induced decrease in serum and intratesticular testosterone and increase in intratesticular pregnenolone concentrations in the hCG-stimulated rats. Simultaneously, the EtOH-induced elevations in the intratesticular pregnenolone/progesterone and androstenedione/testosterone ratios were abolished. In the EtOH-treated rats whose EtOH metabolism was blocked by 4MP pretreatment, the intratesticular testosterone concentrations were negatively correlated with the elevated serum corticosterone levels. It is concluded that: (1) EtOH metabolism is involved in the inhibition of testicular steroidogenesis in vivo. This effect is pronounced during gonadotropin-stimulated conditions. Thus, previously reported "discrepancies" between the in vivo and in vitro results are clarified; (2) corticosterone seems also to be involved in the EtOH-induced inhibition of steroidogenesis. This effect is also pronounced during gonadotropin-stimulated conditions; and (3) without external gonadotropin stimulation other inhibitory mechanisms, such as decreased stimulation by luteinizing hormone, are prevalent.     

Testosterone secretion during gubernacular development and testicular descent in the dog

Serum testosterone concentrations ranged from 0.24 to 1.45 nmol/l between Day 53 post coitum (p.c.) until Day 40 post partum (p.p.) and did not show variations that could be correlated with the process of testicular descent. The intratesticular androgen appeared to be mainly testosterone, its concentration being about 5000-fold higher than that in serum whereas 5 alpha-dihydrotestosterone could not be demonstrated. The intratesticular testosterone concentration at the initiation of gubernacular regression (Day 0) was apparently, but not significantly, higher than at Day 49 p.c. and at Day 40 p.p. The ability of the neonatal canine testis to synthesize testosterone was indicated by increased serum testosterone concentrations after hCG stimulation.     

Effect of in vitro ketoconazole on steroid production in rat testis

In an attempt to confirm where in the testosterone (T) biosynthetic pathway of the rat testis ketoconazole (KTZ) inhibits T production, rat testicular mince was incubated with either 10 micrograms/ml or 100 micrograms/ml KTZ in the presence and absence of hCG (1 IU), and intratesticular pregnenolone (delta 5P), progesterone (P), 17-alpha-hydroxyprogesterone (17 alpha-HP), androstenedione (A) and testosterone (T) were assayed. In the absence of hCG, 10 micrograms/ml KTZ was sufficient to reduce intratesticular T by 80%. At this concentration of KTZ, intratesticular 17 alpha-HP (ng/g testis, mean +/- SEM) increased from 0.3 +/- 0.1 to 1.3 +/- 0.2 (p less than 0.0025), whereas intratesticular A decreased from 84 +/- 7 to 17 +/- 1 (p less than 0.005). KTZ did not inhibit the conversion of P to 17 alpha-HP. From these data it was concluded that KTZ has its inhibitory effect on testosterone biosynthesis in the rat testis primarily at the step catalyzed by the 17,20 desmolase enzyme.     

Prolonged stimulation of adenylate cyclase activity and testosterone production by cholera enterotoxin with suppression of gonadotropin release in rats.

Endocrine effects of cholera enterotoxin (CET) on male gonads were investigated in normal and hypophysectomized rats. After intratesticular injection of 5 micrograms of CET in the bilateral testes of normal rats, serum testosterone concentration remarkably increased after 24 hr, remained significantly elevated for at least 3 days and returned to the control level in 7 days. Serum LH level decreased in the undetectable range after 1--3 days; serum FSH level also significantly decreased after 3 days. Both gonadotropin levels increased 28 days after the injection, when the CET-injected testis decreased in weight and was accompanied by marked loss of germinal cells. When 5 micrograms of CET was injected intratesticularly in the bilateral testes of hypophysectomized rats, adenylate cyclase activity of a CET-injected testis was remarkably stimulated after 6 hr, remained four times elevated for at least 3 days and returned to the control level in 7 days. In relatively good accordance with the increase in adenylate cyclase activity, testosterone content remarkably enhanced in the CET-injected testis. These in vivo data indicate that the intratesticular injection of CET prolongedly stimulates the adenylate cyclase activity of testicular cells including Leydig cells and increases testosterone production, and suggest that the prolonged enzyme stimulation results in the sustained elevation of serum testosterone concentration for at least 3 days, causing the stimulation of the negative feedback mechanism of hypophysealtesticular axis to decrease serum LH levels in the undetectable range.     

Inhibition of NOS-NO System Prevents Autoimmune Orchitis Development in Rats: Relevance of NO Released by Testicular Macrophages in Germ Cell Apoptosis and Testosterone Secretion

Background

Although the testis is considered an immunoprivileged organ it can orchestrate immune responses against pathological insults such as infection and trauma. Experimental autoimmune orchitis (EAO) is a model of chronic inflammation whose main histopathological features it shares with human orchitis. In EAO an increased number of macrophages infiltrate the interstitium concomitantly with progressive germ cell degeneration and impaired steroidogenesis. Up-regulation of nitric oxide (NO)-NO synthase (NOS) system occurs, macrophages being the main producers of NO.

Objective

The aim of our study was to evaluate the role of NO-NOS system in orchitis development and determine the involvement of NO released by testicular macrophages on germ cell apoptosis and testosterone secretion.

Method and Results

EAO was induced in rats by immunization with testicular homogenate and adjuvants (E group) and a group of untreated normal rats (N) was also studied. Blockage of NOS by i.p. injection of E rats with a competitive inhibitor of NOS, L-NAME (8mg/kg), significantly reduced the incidence and severity of orchitis and lowered testicular nitrite content. L-NAME reduced germ cell apoptosis and restored intratesticular testosterone levels, without variations in serum LH. Co-culture of N testicular fragments with testicular macrophages obtained from EAO rats significantly increased germ cell apoptosis and testosterone secretion, whereas addition of L-NAME lowered both effects and reduced nitrite content. Incubation of testicular fragments from N rats with a NO donor DETA-NOnoate (DETA-NO) induced germ cell apoptosis through external and internal apoptotic pathways, an effect prevented by N-acetyl-L-cysteine (NAC). DETA-NO inhibited testosterone released from Leydig cells, whereas NAC (from 2.5 to 15 mM) did not prevent this effect.

Conclusions

We demonstrated that NO-NOS system is involved in the impairment of testicular function in orchitis. NO secreted mainly by testicular macrophages could promote oxidative stress inducing ST damage and interfering in Leydig cell function.     

Intercellular communication between Sertoli cells and Leydig cells in the absence of follicle-stimulating hormone-receptor signaling

Effective interactions among the various compartments of the testis are necessary to sustain efficiency of the spermatogenic process. To study the intercellular communication between the Sertoli and Leydig cells in the complete absence of FSH receptor signaling, we have examined several indices of Leydig cell function in FSH receptor knockout (FORKO) mice. The serum testosterone levels were reduced in the 3- to 4-mo-old adult FORKO males compared to wild-type mice despite no significant alteration in circulating LH levels. Treatment with ovine LH resulted in a dose-dependent increase in serum testosterone levels in all three genotypes (+/+, +/-, and -/-). However, the response in FORKO males was significantly reduced. Similarly, the total intratesticular testosterone per testis was also lower, but the intratesticular testosterone per milligram of testis was significantly elevated in the FORKO males. Western blot analysis revealed an apparent higher expression of the enzyme 3beta-hydroxysteroid dehydrogenase (3beta-HSD) as well as LH-receptor density in the testis of FORKO males. Immunohistochemistry also showed an increase in the intensity of 3beta-HSD staining in the testicular sections of FORKO males. Although LH receptor binding increased per unit weight in FORKO mice, the total LH binding remained the same in all genotypes. Taken together, the results of the present study suggest that, in the absence of FSH receptor signaling, the testicular milieu is altered to affect Leydig cell response to LH such that circulating testosterone is reduced in the adult mutant. Studies are currently under way to understand the mechanisms underlying this phenomenon.     

The effect of testosterone withdrawal and subsequent germ cell depletion on transferrin and sulfated glycoprotein-2 messenger ribonucleic acid levels in the adult rat testis.

We have examined the effects of decreasing intratesticular testosterone concentration and of decreasing germ cell number on levels of transferrin mRNA and sulfated glycoprotein (SGP)-2 mRNA in the adult rat testis. Intact rats received implants of testosterone- and estradiol-filled capsules to suppress LH secretion from the pituitary, thereby suppressing Leydig cell testosterone production. The levels of intratesticular testosterone declined 70% to 20 ng/ml within 3 days, were reduced further to approximately 15 ng/ml by 14 days, and subsequently reached a minimum of about 10 ng/ml. In contrast, the number of elongated spermatids per testis remained unchanged through 14 days, then declined to fewer than 20% of normal between 14 and 28 days, and reached zero by 56 days postimplantation. Likewise, both pachytene spermatocytes and round spermatids declined only after 14 days postimplantation. Northern blots of testicular RNA showed that Sertoli cell transferrin mRNA per testis decreased markedly between 14 and 28 days postimplantation. However, SGP-2 mRNA per testis was unchanged over the time course of the experiment. The decrease in transferrin mRNA, concomitant with germ cell loss, suggests that this mRNA is regulated by the number of germ cells in the testis and not directly by testosterone. In contrast, the constant level of SGP-2 mRNA in the face of reduced intratesticular testosterone and the subsequent loss of germ cells suggests that this mRNA is constitutively maintained in the adult rat testis.     

Rôle du peptide vasoactif intestinal (VIP) dans la stéroïdogenèse et le vieillissement testiculaire

VIP (vasoactive intestinal peptide) neuropeptide has long been considered to be putative regulator of testicular functions.In vitro evidence suggests that VIP could play an important role in testosterone biosynthesis. However, the endogenous role of VIP on testicular functions remained to be demonstrated. In C57BL/6 mice exhibiting complete disruption of the VIP gene, the authors observed that male fertility remained intact but serum testosterone levels were lower than those of WT littermates. At the age of 4 months, this phenotype was accompanied by reduced steroidogenesis due to inhibition of the expression of StAR (steroidogenic acute regulatory protein) and 3ßHSD (3ß-hydroxysteroid dehydrogenase) in the testis. In addition, serum levels of FSH (Follicle-stimulating hormone) but not LH (Luteinizing hormone) were reduced in young KO males. Testicular anatomy also revealed a subtle but significantly higher percentage of degenerated seminiferous tubules in 4-month-old VIP-/-animals compared to WT. In aging animals (15 months old), control males showed typical testicular aging including severe degeneration of seminiferous tubules, a dramatic decrease in serum testosterone levels and a reduction in StAR and 3ß-HSD gene expression. In age-matched VIP-/-males, serum levels of testosterone and steroidogenic enzymes were still very low. Interestingly, in contrast with young mice, testicular degeneration at 15 months was significantly less severe marked in VIP-/-mice than in WT mice. Altogether, these results suggest that: 1) VIP is an important factor for regulating testosterone biosynthesis and FSH secretion and 2) VIP regulates testicular aging.     

Alteration of free sulphydryl content of rat sperm heads by suppression of intratesticular testosterone

Subcutaneous injections of testosterone propionate to adult male rats at a dose of 2.5 or 10 mg/kg body weight, 3 times per week for 7 weeks, resulted in a 75% reduction in serum LH and more than 50% reduction in intratesticular testosterone concentration, but serum FSH levels remained unchanged. The free -SH content, measured as iodo[14C]acetamide binding, increased by 70-100% in testicular sperm heads after suppression of testicular testosterone, and by 25-30% in caput epididymal sperm heads but was decreased by 70-80% in cauda epididymal sperm heads. These results demonstrate an alteration in the oxidative state of sperm nuclear basic proteins, suggesting incomplete nuclear maturation. These changes may be specific for the suppression of intratesticular testosterone, thus illustrating the androgen dependency of sperm head maturation. The contrast effects noted between the iodo[14C]iodoacetamide binding by the caput and the cauda epididymal sperm heads indicate that testosterone propionate treatment may affect the mechanisms regulating the oxidation of the sulphydryl residues in sperm heads during epididymal transit. This alteration may not directly relate to the tissue androgen concentrations.     

Relationship of intratesticular testosterone content of stallions to age, spermatogenesis, Sertoli cell distribution and germ cell-Sertoli cell ratios

Testes were obtained from 47 1-20-year-old stallions during the natural breeding season. Total testicular testosterone and testosterone/g testis increased with age (P less than 0.005), and total testicular testosterone was associated with larger testis size (P less than 0.05). Neither testosterone per gram nor per paired testes were related to total Sertoli cell number (P greater than 0.05), but greater testosterone per paired testes was associated with fewer Sertoli cells per unit of seminiferous tubule length (P less than 0.005) or basement membrane area (P less than 0.02) and with a higher number of germ cells supported per Sertoli cell (P less than 0.05). Although values for testosterone per gram and per paired testes were unrelated (P greater than 0.10) to sperm production/g testis or to the yield of spermatids/spermatogonium, testosterone per paired testes was positively related to sperm production per paired testes (P less than 0.05). It is concluded that intratesticular testosterone increases with age, is related in a positive manner to quantitative rates of sperm production, and can account for some of the differences in sperm production among individual stallions within a single breeding season.     

The effects of long-term administration of either a crude inhibin preparation or an antiserum to FSH on serum hormone levels, testicular function and fertility of adult male rats.

Adult male rats were given either daily injections of ram rete testis fluid for periods of up to 70 days or injections of an antiserum against FSH every 3 days for 90 days. Compared with the control groups, the rats injected with ram rete testis fluid had lowered serum FSH levels, but only at treatment periods of 30 days and less. The levels of LH and testosterone in serum, testicular fluid secretion, sperm counts, testis weights and fertility were not affected by rete testis fluid treatment. The rats injected with anti-FSH serum exhibited an impairment of fertility which was never complete and evident only after 49 days of treatment. After 90 days of anti-FSH treatment, testis weight and free serum FSH were reduced, but sperm counts, testicular fluid secretion and serum levels of LH and testosterone were not affected.     

Modulation of testicular functions by testicular opioid peptides.

The possible physiological role of testicular opioid peptides in the control of testicular functions has been studied. In neonatal rats intratesticular administration of opiate receptor antagonists (naloxone, nalmefene) stimulates Sertoli cell proliferation and secretion. Both in adult and neonatal rats local injection of the testis with opiate receptor antagonists or with beta-endorphin antiserum results in a decrease in steroidogenesis in long-term studies. Treatment of neonatal testis with an enkephalin analogue induces a short-term suppression of testosterone secretion. Further studies were carried out to investigate whether the above described local effects of opiate agonist or antagonist on testicular function are under the regulatory control of testicular nerves. Partial denervation of the testis was performed by testicular injection of 6-hydroxydopamine (a neurotoxin degenerating sympathetic neural structures) or by vasectomy (cutting the inferior spermatic nerve). If testicular administration of opioid agonist or antagonist was combined with partial denervation of the testis, the effects of pharmacological agents influencing testicular opioid level were not evident. The data indicate that opioid peptides synthesized in the testis are components of the intratesticular regulatory system and that local opioid actions are modulated by testicular nerves.     

Bisphenol S induces oxidative stress-mediated impairment of testosterone synthesis by inhibiting the Nrf2/HO-1 signaling pathway

Bisphenol S (BPS) is an environmental endocrine disruptor widely used in industrial production. BPS induces oxidative stress and exhibits male reproductive toxicity in mice, but the mechanisms by which BPS impairs steroid hormone synthesis are not fully understood. Nuclear factor erythroid 2-related factor 2(Nrf2)/HO-1 signaling is a key pathway in improving cellular antioxidant defense capacities. Therefore, this study explored the effects of exposure to BPS on testosterone synthesis in adult male mice and its mechanisms with regard to the Nrf2/HO-1 signaling pathway. Adult male C57BL/6 mice were orally exposed to BPS (2, 20, and 200 mg/kg BW) with sesame oil as a vehicle (0.1 ml/10 g BW) per day for 28 consecutive days. The results showed that compared with the control group, serum testosterone levels were substantially reduced in the 20 and 200 mg/kg BPS treatment groups, and testicular testosterone levels were reduced in all BPS treatment groups. These changes were accompanied by a prominent decrease in the expression levels of testosterone synthesis-related enzymes (STAR, CYP11A1, CYP17A1, HSD3B1, and HSD17B3) in the mouse testis. In addition, BPS induced oxidative stress in the testis by upregulating the messenger RNA and protein levels of Keap1 and downregulating the levels of Nrf2, HO-1, and downstream antioxidant enzymes (CAT, SOD1, and Gpx4). In summary, our results indicate that exposure of adult male mice to BPS can inhibit Nrf2/HO-1 signaling and antioxidant enzyme activity, which induces oxidative stress and thereby may impair testosterone synthesis in testicular tissues, leading to reproductive damage.     

Inhibition of testicular testosterone biosynthesis following experimental varicocele in rats

In an attempt to determine whether defective testicular testosterone (T) biosynthesis may be associated with a varicocele, an experimental study was performed in adult rats whereby a unilateral left varicocele was surgically created. At 2, 4, 8, and 12 wk following the creation of the varicocele, intratesticular T as well as the activities of three (17 alpha-hydroxylase, 17,20-desmolase, and 17 beta-hydroxysteroid dehydrogenase) of the five enzymes in the delta 4 pathway of testicular T biosynthesis were measured. Intratesticular T (ng/g testis +/- SEM) in the left testis decreased significantly from 121 +/- 21 in the control group to 59 +/- 8 in the two-wk varicocele group (p less than 0.01), and remained significantly suppressed throughout the experimental period. The T concentrations in the right testis paralleled those in the left in both the control and varicocele animals. At 2 wk following the creation of the varicocele, the activity (nmol/min/testis +/- SEM) of the 17,20-desmolase enzyme decreased significantly, from 115 +/- 8 in the left testis of control rats to 87 +/- 6 in the left testis of the varicocele animals (p less than 0.025), and remained low throughout the 12 weeks of the study. The activity of the 17 alpha-hydroxylase enzyme was significantly decreased at the 8th and 12th weeks of the study, while the 17 beta-hydroxysteroid dehydrogenase activity did not show any significant change during the study period. The enzyme activities in the right testis paralleled those in the left testis.(ABSTRACT TRUNCATED AT 250 WORDS)     

Impairment of Spermatogenesis in Rats by Mercuric Chloride: Involvement of Low 17β-Estradiol Level in Induction of Acute Oxidative Stress

Mercuric chloride (HgCl₂) has been shown to affect the male reproductive organs, and oxidative stress has been linked with hypospermatogenesis and with male infertility. However, the specific mode of impairment of spermatogenesis during HgCl₂ exposure has not yet been clarified fully. Because of the involvement of 17β-estradiol (E2) in the male reproductive tract and its putative role on spermatogenesis, the present study aimed to investigate the possibility that HgCl₂-induced oxidative stress-mediated modulation of the E2 level exerts adverse effects on testicular steroidogenic and gametogenic activities. HgCl₂ treatment at 50 and 100 ppm for 90 days by continuous oral administration in the drink water resulted in significant dose-dependent fashion decrease in serum and testicular E₂ levels and an increase in testicular testosterone levels in dose-dependent manner, without statistical alteration in serum testosterone level among HgCl₂ exposed groups compared to the control. Cauda epididymal sperm count and motility were decreased significantly (p < 0.01), in a dose-dependent manner, in the HgCl₂-treated groups, and qualitative examination revealed inhibition of spermatogenesis and the preferential loss of maturing and elongated spermatids. The seminiferous tubules were dilated in treated animals. When compared to the control, increase in lipid peroxidation due to toxic effects of HgCl2 was accompanied by significant reduction (p < 0.01) in antioxidant enzymes activities, superoxide dismutase, catalase, and glutathione peroxidase of testes, implicating the presence of oxidative tissue damage. Furthermore, these tissue injuries caused functional impairment as evidenced with testicular elevated activity of lactate dehydrogenase. Unless oxidative stress can lead to cancer development, testis’ tumor markers as beta human chorionic gonadotropin and alpha-fetoprotein levels have shown no significant differences in the HgCl₂-exposed group compared with respect to the control. Large quantities of metal accumulated in the testis tissue are in agreement with the testis-activity failure verified in this tissue. These findings suggest that a decrease in E2 level after mercury exposure may render testis more susceptible to oxidative damage leading to its functional inactivation, thus providing new dimension to mechanisms underlying heavy metal-induced male infertility.