Testosterone suppresses spermatogenesis in juvenile spermatogonial depletion (jsd ) mice

GC-MS-based profiling and ameliorative potential of Carissa opaca Stapf ex Haines fruit against cardiac and testicular toxicity: An In vivo study

Fruit of Carissa opaca Stapf ex Haines (C. opaca) is a feed additive and is commonly used against cardiac dysfunction, fever, asthma, diarrhea, gastrointestinal ailments, and skin diseases. In this study, we aimed to evaluate the metabolic profile and antioxidant potential of C. opaca fruit against carbon tetrachloride (CCl4)-induced cardiotoxicity and testicular toxicity in rats. Gas Chromatoghraphy-Mass Spectrometry (GC-MS) analysis of C. opaca fruit for the identification of potential metabolic profile, followed by methanolic extract of C. opaca and its derived fractions including n-hexane, ethyl acetate, chloroform, butanol, and aqueous were used to assess the antioxidant potential of fruits. Ten groups of rats received different treatments and got evaluated for cardiac and testicular antioxidant enzymes, histological architecture, and serum hormonal levels. GC-MS analysis of methanolic extract of C. opaca fruit showed the presence of some bioactive metabolites like cyclodecane, diethyl 2,6-pyridine dicarboxylate, tetrahydro-geraniol, S-[2-[N, N-Dimethylamino]ethyl]morpoline, 2,3-Methylenedioxyphenol, alpha-d-Glucopyranoside, 5,10-Diethoxy-2,3,7,8-tetrahydro-1H, 6H-dipyrrolo [1,2-a; 1',2'-d] pyrazine and 1,3-Benzothiazol-2(3H)-one,3-(3,3-dimethyl-1-oxobutyl) that corresponds the medicinal properties of C. opaca fruit. Prepared fractions of C. opaca fruits mitigated the toxicity induced by CCl4 in the heart and testicular tissues of rats. Oxidative stress was caused by the inhibition of activities of glutathione and other antioxidant enzymes of the body, while on the other hand elevating the levels of nitrite and hydrogen peroxide. Treatment with C. opaca fruit extract normalized the levels of enzymes, reproductive hormones, and free radicals thus restoring the histopathological and enzymatic biomarkers towards the normal group. The study supports the indigenous use of fruits as an alternative medicine against cardiac dysfunction by providing scientific evidence of protection against CCl4-induced injuries, and it also concludes the antioxidant defensive role in testicular tissues.

The ameliorative effects of methylene blue on testicular damage induced by cisplatin in rats

Cisplatin, a common chemotherapeutic drug, can induce testicular toxicity. Methylene blue, a potent antioxidant, can inhibit the generation of free radicals. This research aimed to study the protective effect of methylene blue against the cisplatin-induced toxicity of the reproductive system in rats. 35 male Wistar rats were divided into five groups: the control group, the cisplatin group (a single dose of 5 mg/kg cisplatin), the low-dose and high-dose methylene blue + cisplatin (2 and 4 mg/kg of methylene blue, respectively, for 7 days) and the methylene blue group (4 mg/kg of methylene blue, for 7 days). The treatments were applied through intraperitoneal injection. Cisplatin treatment reduced the sperm parameters and serum testosterone levels significantly. Methylene blue treatment increased the sperm count (p < .001), viability (p < .001) and motility (p < .001) compared to the cisplatin group. The methylene blue group showed a significant increase in the levels of testosterone compared to the cisplatin group (p < .001) and reverted histopathological changes in cisplatin-treated groups. Immunohistochemical evaluation of the caspase-3 protein revealed that the treatment with methylene blue has significant anti-apoptotic effects on testicular tissue damage. In conclusion, methylene blue can attenuate the cisplatin-induced histological damages and improve the sperm parameters.

Gonadoprotective ability of Vincetoxicum arnottianum extract against bisphenol A-induced testicular toxicity and hormonal imbalance in male Sprague Dawley rats

Vincetoxicum arnottianum (Wight) of family Apocynaceae is a rich source of therapeutic alkaloids, phenolics and flavonoids. Study aims to evaluate the protective potential of methanol extract of Vincetoxicum arnottianum (VAM) on bisphenol A (BPA)-induced testicular toxicity in male Sprague Dawley rat. Quantitative analysis of VAM for total phenolic (TPC), total flavonoid (TFC) and total alkaloid content (TAC) along with HPLC analysis for polyphenolics was carried out. BPA-induced testicular toxicity was determined through analysis of antioxidant enzymes, DNA damages and testicular histopathology along with reproductive hormones in serum of rat. VAM was constituted of TFC (382.50 ± 1.67 μg GAE/mg), TPC (291.17 ± 0.82 μg RE/mg), TAC (16.5 ± 0.5%), ferulic acid (2.2433 μg/mg) and vanillic acid (2.1249 μg/mg). VAM co-administration to BPA-treated rats attenuated the toxic effects of BPA and restored the body and testis weights. Altered level of luteinizing hormone (LH), testosterone and follicle-stimulating hormone (FSH) in serum, and level of antioxidants (GSH, POD, CAT and SOD) and nitric oxide in testis tissues of BPA-induced toxicity were significantly restored by VAM. Histological and comet assay studies also sanctioned the protective potential of VAM in BPA-intoxicated rats. The presence of polyphenols and alkaloids might contribute towards the scavenging and ameliorative potential of VAM in testicular toxicity induced by BPA.

The Luteinizing Hormone-Testosterone Pathway Regulates Mouse Spermatogonial Stem Cell Self-Renewal by Suppressing WNT5A Expression in Sertoli Cells

Spermatogenesis originates from self-renewal of spermatogonial stem cells (SSCs). Previous studies have reported conflicting roles of gonadotropic pituitary hormones in SSC self-renewal. Here, we explored the role of hormonal regulation of SSCs using Fshb and Lhcgr knockout (KO) mice. Although follicle-stimulating hormone (FSH) is thought to promote self-renewal by glial cell line-derived neurotrophic factor (GDNF), no abnormalities were found in SSCs and their microenvironment. In contrast, SSCs were enriched in Lhcgr-deficient mice. Moreover, wild-type SSCs transplanted into Lhcgr-deficient mice showed enhanced self-renewal. Microarray analysis revealed that Lhcgr-deficient testes have enhanced WNT5A expression in Sertoli cells, which showed an immature phenotype. Since WNT5A was upregulated by anti-androgen treatment, testosterone produced by luteinizing hormone (LH) is required for Sertoli cell maturation. WNT5A promoted SSC activity both in vitro and in vivo. Therefore, FSH is not responsible for GDNF regulation, while LH negatively regulates SSC self-renewal by suppressing WNT5A via testosterone.

Increasing testicular temperature by exposure to elevated ambient temperatures restores spermatogenesis in adult Utp14b (jsd) mutant (jsd) mice

Because mutations in the human UTP14C gene are associated with male infertility, we sought to develop a method for fertility restoration in azoospermic mice with a mutation in the orthologous Utp14b(jsd) (jsd) gene that have spermatogonial arrest. The method is based on our observation that elevation of testicular temperatures restores spermatogonial differentiation in jsd mutant mice. To non-surgically raise intrascrotal temperatures we placed these mice in incubators at different elevated ambient temperatures. Exposure of jsd/jsd mice to ambient temperatures of 34.5 °C or 35.5 °C for 24 days increased the proportion of tubules with spermatocytes from 0% in untreated controls to over 80%. As those higher temperatures interfere with spermatid differentiation, the mice were then transferred to incubators at 32-32.5 °C for the next 24 days. These environments allowed differentiation to progress, resulting in up to 42% of tubules having late spermatids and about half of the mutant mice having spermatozoa in testicular suspensions. When these spermatozoa were used in intracytoplasmic sperm injection, all gave rise to viable healthy offspring with normal weight gain and fertility. The successful restoration of fertility in Utp14b mutant mice suggests that transient testicular warming might also be useful for spermatogenesis recovery in infertile men with UTP14C gene mutations.

Effect of Carissa opaca leaves extract on lipid peroxidation, antioxidant activity and reproductive hormones in male rats

BACKGROUND

Carissa opaca leaves are traditionally used in the treatment of male dysfunction and hormonal disorder as well as in oxidative stress in Pakistan and Asia. The present study was designed to assess the protective effects of methanolic extract of Carissa opaca leaves (MLC) on carbon tetrachloride (CCl4)-induced reproductive stress in male rats and bioactive constituents responsible for the activity.

METHODS

CCl4 was induced in 42 male rats for eight weeks and checked the protective efficacy of methanolic extract of Carissa opaca leaves at various hormonal imbalances, alteration of antioxidant enzymes, DNA fragmentation levels and lipid peroxidation caused testicular fibrosis in testis while High performance Liquid Chromatography (HPLC) was used for detection of bioactive components.

RESULTS

HPLC characterization revealed the presence of isoquercitin, hyperoside, vitexin, myricetin and kaempherol. CCl4 caused significant alteration in the secretion of reproductive hormones. Activity of antioxidant enzymes viz; catalase, superoxide dimutase and phase II metabolizing enzymes including glutathione peroxidase, glutathione reductase and reduced glutathione was decreased while DNA fragmentation, hydrogen per oxide contents and thiobarbituric acid reactive substances (TBARS) were increased with CCl4 treatment. Co-administration of 100 mg/kg and 200 mg/kg b.w. MLC effectively ameliorated the alterations in the biochemical markers; hormonal and molecular levels.

CONCLUSION

Protective effects of methanolic extract of Carissa opaca against CCl4-induced antioxidant and hormonal dysfunction which might be due to bioactive compound present in extract.

Ameliorating effect of various fractions of Rumex hastatus roots against hepato- and testicular toxicity caused by CCl4

Effect of methanolic extract of Rumex hastatus roots (MRR) and its derived fractions, n-hexane (HRR), ethyl acetate (ERR), chloroform (CRR), butanol (BRR), and aqueous extract (ARR), was studied against carbon tetrachloride (CCl4) induced hepato and testicular toxicity in rats. Intraperitoneal dose of 20 percent CCl4 (0.5 ml/kg bw) was administered twice a week for eight weeks to a group of rats. Other groups were given CCl4 and various fractions of R. hastatus roots (200 mg/kg bw). CCl4 treatment depleted glutathione contents and activities of antioxidant enzymes while increased the concentration of lipid peroxides (TBARS) along with corresponding DNA injuries and histopathological damages. Supplementation with various fractions of R. hastatus roots (200 mg/kg body weight) attenuated the toxicity of CCl4 in liver and testis tissues through improvement in the serological, enzymatic, and histological parameters towards the normal. Posttreatment of R. hastatus roots (200 mg/kg body weight) also reversed the alteration in reproductive hormonal secretions and DNA damages in CCl4 treated rats. The results clearly demonstrated that R. hastatus treatment augments the antioxidants defense mechanism and provides the evidence that it may have a therapeutic role in free radical mediated diseases.

Effect of lead and cadmium co-exposure on testicular steroid metabolism and antioxidant system of adult male rats

The mechanism of testicular toxicity of lead (Pb) and cadmium (Cd) is poorly understood. Previous studies focused on single metal-related changes in testicular toxicity. This study points towards the possible involvement of Pb- and Cd-induced oxidative stress in the suppression of steroidogenesis. The oxidative status of testis of adult male rats exposed to Pb acetate and cadmium acetate either alone or in combination at a dose of 0.025 mg kg(-1) body weight of metal intraperitoneally for 15 days was studied. Pb and Cd caused an increase in reactive oxygen species (ROS) by elevating testicular malondialdehydes (MDA) and decrease in activities of testicular antioxidant enzymes superoxide dismutase (SOD), catalase, glucose 6 phosphate dehydrogenase (G6PDH) and glutathione-S-transferase (GST) in mitochondrial and/or post-mitochondrial fraction. Activities of steroidogenic enzymes 3β and 17β-hydroxysteroid dehydrogenase also decreased significantly leading to altered testosterone production. Metal-exposed groups showed significantly decreased testicular and epididymal sperm count. Epididymal sperm motility and viability was also decreased on Pb and Cd exposure. Cd exposure showed more toxic effect than lead exposure, while combined exposure demonstrated least toxicity. In vitro experiments showed that vitamin C restores steroidogenic enzyme activities, suggesting that Pb- and Cd-induced ROS inhibits the testicular steroidogenesis.

Androgen suppression-induced stimulation of spermatogonial differentiation in juvenile spermatogonial depletion mice acts by elevating the testicular temperature

Why both testosterone (T) suppression and cryptorchidism reverse the block in spermatogonial differentiation in adult mice homozygous for the juvenile spermatogonial depletion (jsd) mutation has been a conundrum. To resolve this conundrum, we analyzed interrelations between T suppression, testicular temperature, and spermatogonial differentiation and used in vitro techniques to separate the effects of the two treatments on the spermatogonial differentiation block in jsd mice. Temporal analysis revealed that surgical cryptorchidism rapidly stimulated spermatogonial differentiation whereas androgen ablation treatment produced a delayed and gradual differentiation. The androgen suppression caused scrotal shrinkage, significantly increasing the intrascrotal temperature. When serum T or intratesticular T (ITT) levels were modulated separately in GnRH antagonist-treated mice by exogenous delivery of T or LH, respectively, the inhibition of spermatogonial differentiation correlated with the serum T and not with ITT levels. Thus, the block must be caused by peripheral androgen action. When testicular explants from jsd mice were cultured in vitro at 32.5 C, spermatogonial differentiation was not observed, but at 37 C significant differentiation was evident. In contrast, addition of T to the culture medium did not block the stimulation of spermatogonial differentiation at 37 C, and androgen ablation with aminoglutethimide and hydroxyflutamide did not stimulate differentiation at 32.5 C, suggesting that T had no direct effect on spermatogonial differentiation in jsd mice. These data show that elevation of temperature directly overcomes the spermatogonial differentiation block in adult jsd mice and that T suppression acts indirectly in vivo by causing scrotal regression and thereby elevating the testicular temperature.

Clinical evaluation of non-surgical sterilization of male cats with single intra-testicular injection of calcium chloride

Background

Calcium chloride solution is an established injectable sterilant in dogs and other mammals. With cat populations a continuing problem, we sought to explore its first use in cats. Six cats per group were injected with 5%, 10% or 20% calcium chloride dihydrate in saline solution with lignocaine hydrochloride, a local anaesthetic.

Results

At the 60^th day post-injection, cat testes were collected and showed complete testicular necrosis and replacement by fibrous tissue; very low sperm counts; and reduction of serum testosterone by at least 70% in 20% dose. Androgenic enzyme activities and their expressions were also reduced in all the treated groups along with intra-testicular testosterone concentration was also low. Increased testicular lipid peroxidation, with reduced antioxidants and mitochondrial membrane potential, were evident following calcium chloride treatments. However, there were no apparent changes in serum concentrations of cortisol, fasting blood sugar level, blood urea nitrogen, packed cell volume, or total serum protein following calcium chloride injection, suggesting that this method of sterilization is not associated with any general stress response.

Conclusion

Calcium chloride solution demonstrates potential for androgenesis-eliminating nonsurgical sterilization of male cats in addition to its proven efficacy in dogs and other mammals.

Gene expression alterations by conditional knockout of androgen receptor in adult Sertoli cells of Utp14b jsd/jsd (jsd) mice

Spermatogenesis is dependent primarily on testosterone action on the Sertoli cells, but the molecular mechanisms have not been identified. Attempts to identify testosterone-regulated target genes in Sertoli cells have used microarray analysis of gene expression in mice lacking the androgen receptor (AR) in Sertoli cells (SCARKO) and wild-type mice, but the analyses have been complicated both by alteration of germ cell composition of the testis when pubertal or adult mice were used and by differences in Sertoli-cell gene expression from the expression in adults when prepubertal mice were used. To overcome these limitations and identify AR-regulated genes in adult Sertoli cells, we compared gene expression in adult jsd (Utp14b jsd/jsd, juvenile spermatogonial depletion) mouse testes and with that in SCARKO-jsd mouse testes, since their cellular compositions are essentially identical, consisting of only type A spermatogonia and somatic cells. Microarray analysis identified 157 genes as downregulated and 197 genes as upregulated in the SCARKO-jsd mice compared to jsd mice. Some of the AR-regulated genes identified in the previous studies, including Rhox5, Drd4, and Fhod3, were also AR regulated in the jsd testes, but others, such as proteases and components of junctional complexes, were not AR regulated in our model. Surprisingly, a set of germ cell–specific genes preferentially expressed in differentiated spermatogonia and meiotic cells, including Meig1, Sycp3, and Ddx4, were all upregulated about 2-fold in SCARKO-jsd testes. AR-regulated genes in Sertoli cells must therefore be involved in the regulation of spermatogonial differentiation, although there was no significant differentiation to spermatocytes in SCARKO-jsd mice. Further gene ontogeny analysis revealed sets of genes whose changes in expression may be involved in the dislocation of Sertoli cell nuclei in SCARKO-jsd testes.

Gene expression alterations by conditional knockout of androgen receptor in adult sertoli cells of Utp14b(jsd/jsd) (jsd) mice

Spermatogenesis is dependent primarily on testosterone action on the Sertoli cells, but the molecular mechanisms have not been identified. Attempts to identify testosterone-regulated target genes in Sertoli cells have used microarray analysis of gene expression in mice lacking the androgen receptor (AR) in Sertoli cells (SCARKO) and wild-type mice, but the analyses have been complicated both by alteration of germ cell composition of the testis when pubertal or adult mice were used and by differences in Sertoli-cell gene expression from the expression in adults when prepubertal mice were used. To overcome these limitations and identify AR-regulated genes in adult Sertoli cells, we compared gene expression in adult jsd (Utp14b(jsd/jsd), juvenile spermatogonial depletion) mouse testes and with that in SCARKO-jsd mouse testes, since their cellular compositions are essentially identical, consisting of only type A spermatogonia and somatic cells. Microarray analysis identified 157 genes as downregulated and 197 genes as upregulated in the SCARKO-jsd mice compared to jsd mice. Some of the AR-regulated genes identified in the previous studies, including Rhox5, Drd4, and Fhod3, were also AR regulated in the jsd testes, but others, such as proteases and components of junctional complexes, were not AR regulated in our model. Surprisingly, a set of germ cell-specific genes preferentially expressed in differentiated spermatogonia and meiotic cells, including Meig1, Sycp3, and Ddx4, were all upregulated about 2-fold in SCARKO-jsd testes. AR-regulated genes in Sertoli cells must therefore be involved in the regulation of spermatogonial differentiation, although there was no significant differentiation from spermatocytes in SCARKO-jsd mice. Further gene ontogeny analysis revealed sets of genes whose changes in expression may be involved in the dislocation of Sertoli cell nuclei in SCARKO-jsd testes.

Mouse cumulus-denuded oocytes restore developmental capacity completely when matured with optimal supplementation of cysteamine, cystine, and cumulus cells

Our objectives were to study how cysteamine, cystine, and cumulus cells (CCs), as well as oocytes interact to increase oocyte intracellular glutathione (GSH) and thereby to establish an efficient in vitro maturation system for cumulus-denuded oocytes (DOs). Using M16 that contained no thiol as maturation medium, we showed that when supplemented alone, neither cystine nor cysteamine promoted GSH synthesis of mouse DOs, but they did when used together. Although goat CCs required either cysteamine or cystine to promote GSH synthesis, mouse CCs required both. In the presence of cystine, goat CCs produced cysteine but mouse CCs did not. Cysteamine reduced cystine to cysteine in cell-free M16. When TCM-199 that contained 83 microM cystine was used as maturation medium, supplementation with cysteamine alone had no effect, but supplementation with 100 microM cysteamine and 200 microM cystine increased blastulation of DOs matured with CC coculture to a level as high as achieved in cumulus-surrounded oocytes (COCs). Similar numbers of young were produced after two-cell embryos from mouse COCs or CC-cocultured DOs matured with optimal thiol supplementation were transferred to pseudopregnant recipients. It is concluded that 1) mouse CCs can use neither cysteamine nor cystine to promote GSH synthesis, but goat CCs can use either one; 2) goat CCs promote mouse oocyte GSH synthesis by reducing cystine to cysteine, but how they use cysteamine requires further investigation; and 3) mouse DOs can use neither cystine nor cysteamine for GSH synthesis, but they restore developmental capacity completely when matured in the presence of optimum supplementation of cysteamine, cystine, and CCs.

Estrogen receptor polymorphism, estrogen content and idiopathic scoliosis in human: a possible genetic linkage

Idiopathic scoliosis (IS) is a largely diffused disease in human population but its pathogenesis is still unknown. There is a relationship between scoliotic phenotype and the patient age, since in the early stage the pathology shows a ratio of 50% between male and female teenagers. During puberty the sex ratio is 8.4/1 (female/male), suggesting a sex-conditioned manifestation of the disease. Genetic inheritance of idiopathic scoliosis is still unclear although some authors claim for its X-linked dominant inheritance. There is large agreement in considering the IS as a sex-conditioned disease, in terms of steroid content and their receptor activity, although no evidence has been found yet. The blood content of 17beta-estradiol in teenagers with IS shows lower levels than teenagers of the same age without IS. Also testosterone and progesterone content are lower in IS girls with respect to the control girls. Furthermore, we extracted DNA from white blood cells of IS patients and their relatives until the third generation in order to examine estrogen receptor alpha polymorphisms, considering this tool a plausible molecular marker for IS prognosis. In this respect, we identified four polymorphisms in the exons encoding for the steroid binding domain and two other in the trans-activation domain. Our results show a clear relationship with clinical manifestation of IS.

Androgen receptor in Sertoli cells is not required for testosterone-induced suppression of spermatogenesis, but contributes to Sertoli cell organization in Utp14b jsd mice

Testosterone acting through the androgen receptor (AR) maintains the arrest of spermatogonial differentiation in juvenile spermatogonial depletion (jsd mutation in the Utp14b gene) mutant adult male mice. It is not known which of the somatic cell types expressing AR mediates this inhibition. To determine whether Sertoli cells are responsible, we selectively eliminated AR in Sertoli cells in jsd mice containing a floxed-Ar gene and an anti-Müllerian hormone-Cre transgene. In these Sertoli AR-knockout (SCARKO)-jsd mice, spermatogonial differentiation did not recover. However, the normal organization of Sertoli cell nuclei was drastically disrupted in SCARKO-jsd mice compared with SCARKO or jsd mice. In addition, the extent of ectoplasmic specializations was reduced; tight junctions were not found; vinculin, an anchoring protein found in ectoplasmic specializations, became uniformly distributed in the cytoplasm; and the adult Sertoli cells showed excess heterochromatin subjacent to their nuclear envelope. Despite the abnormalities in Sertoli cells in SCARKO-jsd mice, global suppression of testosterone action and levels was still effective in restoring the differentiated germ cells, and this was accompanied by an improved arrangement of Sertoli cell nuclei. We conclude that Sertoli cells are not targets for the testosterone-mediated inhibition of spermatogonial differentiation in jsd mice, and that both AR in Sertoli cells and the presence of differentiated germ cells contribute to maintaining the organization of Sertoli cells within the seminiferous tubules.

In vitro culture and differentiation of buffalo (Bubalus bubalis) spermatogonia

The objective of this study was to develop a culture system which could support buffalo spermatogonia differentiation into spermatids in vitro. Testes from 3- to 5-month-old buffaloes were decapsulated and seminiferous tubules were enzymatically dissociated to recover spermatogonia and sertoli cells. The cells were cultured in modified Dulbecco modified Eagle medium supplemented with different concentrations of foetal bovine serum, retinol, testosterone for 2 months at 37 degrees C. Spermatogonia and sertoli cells were identified with an antibody against c-kit or GATA4, respectively. The viability of spermatogonia in the media supplemented with different concentrations of serum was all significantly higher (p < 0.05) compared with that in the medium without serum. A-paired or A-aligned spermatogonia and spermatogonial colonies (AP-positive) were observed after 7-10 days of culture and spermatid-like cells with a flagellum (6-8 microm) appeared after 30 days of culture. For cultured conditions, retinol could not significantly promote the formation of spermatid-like cells (p > 0.05), whereas supplementation of testosterone could significantly promote (p < 0.05) the formation of spermatid-like cells after 41 days of culture. The expression of the spermatid-specific marker gene (PRM2) was identified after 30 days of culture by RT-PCR. Yet, the transition protein 1 (TP1, a haploid makers) was not detected. Meanwhile, spermatids developed in vitro were also confirmed by Raman spectroscopy. These results suggest that buffalo spermatogonia could differentiate into spermatids in vitro based on the analysis of their morphology, PRM2 expression and Raman spectroscopy. Yet, the normality of the spermatid-like cells was not supported by TP1 expression.

Testicular development of Zebu bulls after chronic treatment with a gonadotropin-releasing hormone agonist

The objective was to compare testis characteristics of Zebu bulls treated with the GnRH agonist, deslorelin, at different times and for different durations during their development. An additional objective was to determine the usefulness of a stain for the transcription factor GATA-binding protein 4 (GATA-4) as a specific marker for Sertoli cell nuclei in cattle. Bulls (54) were allocated to nine groups (n = 6) and received s.c. deslorelin implants as follows: G1 = from birth to 3 mo of age; G2 = from 3 to 6 mo; G3 = from 6 to 9 mo; G4 = from 9 to 12 mo; G5 = from birth to 15 mo; G6 = from 3 to 15 mo; G7 = from 6 to 15 mo; G8 = from 12 to 15 mo; and G9 (control) = no implant. Bulls were castrated at 19 mo of age. Paraffin sections (10 microm) were subjected to quantitative morphometry and GATA-4 immunohistochemistry. At castration, all bulls in the control group (6/6) had attained puberty (scrotal circumference > or = 28 cm), whereas a smaller proportion (P < 0.05) had reached puberty in G2 (2/5) and G6 (1/6). Bulls in G2 and G6 also had a lesser (P < 0.05) testis weight compared with the control group. Total volume of seminiferous epithelium and total daily sperm production in G2 and G6 were only half that observed in the control group. Spermatids were observed in less than 50% of seminiferous tubules in G2, G6, and G7 compared with 82% in the control group (P < 0.05). Staining for GATA-4 was specific for and abundant in the Sertoli cell nucleus in both pre- and postpubertal bulls, and no other cell nucleus inside the seminiferous tubule was positive for GATA-4. Total number of Sertoli cells was not affected by treatment (P = 0.45), but nuclear volume was smaller in G2 and G6 (P < 0.05) compared with the control group. In conclusion, treatment of Zebu bulls with deslorelin had no apparent beneficial effect on testis development and delayed puberty when treatment was initiated at 3 mo of age. Staining for GATA-4 was a useful method for identifying and quantifying Sertoli cell nuclei in both pre- and postpubertal bulls.

Genetic Factors Contributing to Defective Spermatogonial Differentiation in Juvenile Spermatogonial Depletion (Utp14bjsd) Mice1

Male mice that are homozygous for the juvenile spermatogonial depletion (jsd) mutation in the Utp14b gene undergo several waves of spermatogenesis. However, spermatogonial differentiation ceases and in adults, spermatogonia are the only germ cells that remain. To understand further the blockage in spermatogonial differentiation in Utp14b(jsd) mutant mice, we correlated the rate and severity of spermatogonial depletion and the restoration of spermatogenesis following the suppression of testosterone or elevation of testicular temperature with the genetic background. Testes from Utp14b(jsd) mutant mice on B6, C3H, and mixed C3H-B6-129 (HB129) genetic backgrounds all showed steady decreases in the numbers of normal spermatogonia between 8 wk and 20 wk of age. The percentages of tubules with differentiating germ cells were higher and the spermatogonia were more advanced in C3H- background than in B6- or HB129-background Utp14b(jsd) mice. Genetic crosses showed that the source of the Y chromosome was a major factor in determining the severity of spermatogonial depletion in Utp14b(jsd) mutant mice. When Utp14b(jsd) mutants were subjected to total androgen ablation or unilateral cryptorchidization, spermatogenic development recovered markedly in the C3H and HB129 background but showed less recovery in the B6-background mice. The differences noted between the strains in terms of the severity of spermatogonial depletion were not dependent upon testosterone level or scrotal temperature but correlated with the magnitudes of the effects of elevated temperature on normal and Utp14b(jsd) mutant spermatogenic cells. Thus, the abilities of germ cells in certain strains to survive elevated temperatures may be related to their abilities to maintain some degree of differentiation potential after the Utp14b(jsd) gene is mutated.

Testicular toxicity of profenofos in matured male rats

To investigate the effect of the phosphorothoate insecticide profenofos on male specific gene expression on rat testis, 16-week-old Wistar rats were orally administered at dose of 17.8 mg/kg twice weekly for 65 days. Gene expression in the testes was monitored by DNA microarray analysis and real-time RT-PCR, which revealed that genes related to steroidogenesis including cytochrome P450 17A1 (CYP17A1), steroidogenic acute regulatory protein (StAR) and CYP11A1 were significantly increased. Besides the testes were histopathologicaly examined, which revealed testicular destruction and degeneration represented by a layer of columnar epithelium, oedematous changes surrounding the seminiferous tubules besides vacuolated spermatogonial cells and more elongated Leydig cells. These data suggest that profenofos considered as one of the male reproductive toxicants. Furthermore, we propose that the above three steroidogenic-related genes and the gene of acrosomal reaction as potential biomarkers of testicular toxicity.

Sterilization of male stray dogs with a single intratesticular injection of calcium chloride: a dose-dependent study

OBJECTIVE

To study a method of chemical sterilization and its efficacy in adult male stray dogs.

METHODS

Sterilization was performed 45 days after a single bilateral intratesticular injection of calcium chloride (CaCl(2)) at the doses of 5, 10, 15 or 20 mg per testis per kg body weight.

RESULTS

Histomorphological measures of testes showed total necrosis of testicular tissue at 45 days after an injection of either 10 or 15 or 20 mg CaCl(2) along with fibrosis and hyalinization in seminiferous tubules and interstitial spaces. Infiltration of leucocytes was also observed with the 10- or 15-mg dose. Disintegration of germ cell arrangement in seminiferous tubules and washing out of germ cells from the tubules were noted with the 5-mg dose. Relative organ weight, epididymal sperm count, plasma and intratesticular concentrations of testosterone, testicular activities of Delta(5),3beta-hydroxysteroid dehydrogenase (Delta(5),3beta-HSD), 17beta-hydroxysteroid dehydrogenase (17beta-HSD), glutathione peroxidase (GPx), glutathione S-transferase (GST) and superoxide dismutase (SOD) and testicular contents of glutathione (GSH) and glutathione disulphide (GSSG) and the ratio of GSH/GSSG, all were declined in each of the calcium chloride treated groups in comparison to the control group. Increases occurred in testicular malondialdehyde (MDA) and plasma concentrations of LH and FSH with each of the treatments by comparison with the control group. Plasma concentrations of cortisol, fasting blood sugar level, blood urea nitrogen as well as packed cell volume (PCV) and total plasma protein were recorded to monitor the changes in chronic stress in the experimental animals. Changes in these parameters were not significant.

CONCLUSION

An intratesticular injection of CaCl(2) at specified doses could be a suitable method of sterilization in preference to surgical castration of dogs.

Relation between serum xenobiotic-induced receptor activities and sperm DNA damage and sperm apoptotic markers in European and Inuit populations

Persistent organic pollutants (POPs) can interfere with hormone activities and are suspected as endocrine disrupters involved in disorders, e.g. reproductive disorders. We investigated the possible relation between the actual integrated serum xenoestrogenic, xenoandrogenic and aryl hydrocarbon receptor (AhR) activities, and the sperm DNA damage and sperm apoptotic markers of 262 adult males (54 Inuits from Greenland, 69 from Warsaw (Poland), 81 from Sweden, and 58 from Kharkiv (Ukraine)) exposed to different levels of POPs. Xenobiotic-induced receptor activities were determined by receptor-mediated luciferase reporter gene expression. Sperm DNA damage was measured using terminal deoxynucleotidyl transferase-driven dUTP nick labeling assay (TUNEL) and pro- (Fas) and anti-apoptotic (Bcl-xL) markers were determined by immune methods. Different features of xenobiotic-induced receptor activity in serum and sperm DNA fragmentation and apoptotic markers existed between the Inuits and the European Caucasians. Negative correlations between xenobiotic-induced receptor activities and DNA damage were found for Inuits having relatively lower xenoestrogenic, lower dioxin-like activity, and lower sperm DNA damage, but higher xenoandrogenic activity. In contrast, in the European groups, xenobiotic-induced receptor activities were found to be positively correlated with the DNA damage. Further research must elucidate whether altered receptor activities in concerted action with genetic and/or nutrient factors may have protecting effect on sperm DNA damage of the Inuit population.

Spermatogonial differentiation in juvenile spermatogonial depletion (jsd) mice with androgen receptor or follicle-stimulating hormone mutations

The jsd mice experience a single wave of spermatogenesis, followed by an arrest of spermatogenesis because of a block in spermatogonial differentiation. Previous pharmacological and surgical studies have indicated that testosterone (T) and low scrotal temperatures but not FSH block spermatogonial differentiation in jsd mice. We sought to test these observations by genetic approaches by producing male jsd mutant mice with either defective androgen receptor (AR, Tfm mutation) or a deficiency of FSH (fshb(-/-)). In adult jsd-Tfm double-mutant mice, the tubule differentiation index was 95% compared with 14% in jsd littermates, suggesting that general ablation of AR function restored spermatogonial differentiation in jsd mice. The results indicated that this enhancement of differentiation was primarily a result of elevation of temperature caused by the cryptorchid position of the testis in jsd-Tfm double-mutant mice, which resulted from the lack of AR in the gubernaculum. The low levels of T were not a factor in the release of the spermatogonial differentiation block in the jsd-Tfm mice, but we were unable to determine whether inactivation of AR in the adult jsd testis had a direct effect on the restoration of spermatogonial differentiation because the elevated temperature bypassed the T-induced block in spermatogonial differentiation. Although spermatogonia were indeed present in adult jsd-fshb double-mutant mice and were capable of differentiation after androgen deprivation, these mice had a tubule differentiation index of 0%, ruling out the possibility that endogenous FSH inhibited spermatogonial differentiation in jsd mice. The results are consistent in support of the hypothesis that inhibition of spermatogonial differentiation in jsd mice is a result of T acting through the AR only at scrotal temperatures.

Effects of chronic exposure to sodium arsenite on hypothalamo-pituitary-testicular activities in adult rats: possible an estrogenic mode of action

BACKGROUND

Inorganic arsenic is a major water pollutant and a known human carcinogen that has a suppressive influence on spermatogenesis and androgenesis in male reproductive system. However, the actual molecular events resulting in male reproductive dysfunctions from exposure to arsenic remain unclear. In this context, we evaluated the mode of action of chronic oral exposure of sodium arsenite on hypothalamo-pituitary- testicular activities in mature male albino rats.

METHODS

The effect of chronic oral exposure to sodium arsenite (5 mg/kg body weight/day) via drinking water without or with hCG (5 I.U./kg body weight/day) and oestradiol (25 micrograms oestradiol 3-benzoate suspended in 0.25 ml olive oil/rat/day) co-treatments for 6 days a week for 4 weeks (about the duration of two spermatogenic cycle) was evaluated in adult male rats. Changes in paired testicular weights, quantitative study of different varieties of germ cells at stage VII of spermatogenic cycle, epididymal sperm count, circulatory concentrations of hormones (LH, FSH, testosterone and corticosterone), testicular activities of delta 5, 3beta-hydroxysteroid dehydrogenase (delta 5, 3beta-HSD), 17 beta-hydroxysteroid dehydrogenase (17 beta-HSD), sorbitol dehydrogenase (SDH), acid phosphatase (ACP), alkaline phosphatase (ALP), and lactate dehydrogenase (LDH), as well as the levels of biogenic amines (dopamine, noradrenaline and 5-hydroxytryptamine (5-HT)) in the hypothalamus and pituitary were monitored in this study. Hormones were assayed by radioimmuno- assay or enzyme- linked immunosorbent assay and the enzymes were estimated after spectrophotometry as well as the biogenic amines by HPLC electrochemistry.

RESULTS

Sodium arsenite treatment resulted in: decreased paired testicular weights; epididymal sperm count; plasma LH, FSH, testosterone and testicular testosterone concentrations; and increased plasma concentration of corticosterone. Testicular enzymes such as delta 5, 3 beta-HSD, 17 beta-HSD, and sorbitol dehydrogenase (SDH) were significantly decreased, but those of acid phosphatase (ACP), alkaline phosphatase (ALP), and lactate dehydrogenase (LDH) were significantly increased. A decrease in dopamine or an increase in noradrenaline and 5-HT in hypothalamus and pituitary were also noted after arsenic exposure. Histological evaluation revealed extensive degeneration of different varieties of germ cells at stage VII of spermatogenic cycle in arsenic exposed rats. Administration of human chorionic gonadotrophin (hCG) along with sodium arsenite partially prevented the degeneration of germ cells and enhanced paired testicular weights, epididymal sperm count, plasma and intratesticular testosterone concentrations, activities of delta 5, 3beta-HSD, 17 beta-HSD and sorbitol dehydrogenase along with diminution in the activities of ACP, ALP and LDH. Since many of the observed arsenic effects could be enhanced by oestradiol, it is suggested that arsenic might somehow acts through an estrogenic mode of action.

CONCLUSION

The results indicate that arsenic causes testicular toxicity by germ cell degeneration and inhibits androgen production in adult male rats probably by affecting pituitary gonadotrophins. Estradiol treatment has been associated with similar effects on pituitary testicular axis supporting the hypothesis that arsenite might somehow act through an estrogenic mode of action.

Both testosterone and follicle-stimulating hormone independently inhibit spermatogonial differentiation in irradiated rats

Simultaneous suppression of both testosterone and FSH with GnRH antagonists (GnRH-ant) reverses the radiation-induced block in spermatogonial differentiation in F1 hybrids of Lewis and Brown-Norway rats. Although addition of exogenous testosterone restores the block, it also raises FSH, and hence it had not been possible to conclusively determine which hormone was inhibiting spermatogonial differentiation. In the present study, we establish the relative roles of testosterone and FSH in this inhibition using three different approaches. The first approach involved the treatment of irradiated rats, in which differentiation was stimulated by GnRH-ant plus flutamide, with FSH for 2 wk; the FSH reduced the percentage of tubules that were differentiated (TDI) by about 2-fold, indicating that FSH does have an inhibitory role. The second approach involved treatment of irradiated, hypophysectomized rats with exogenous testosterone for 10 wk; testosterone also reduced the TDI, demonstrating that testosterone had a definite inhibitory effect, independent of pituitary hormones. Furthermore, in this protocol we showed that TDI in the hypophysectomized testosterone-treated group, which had higher intratesticular testosterone levels but lacked FSH, was slightly higher than the TDI in a GnRH-antagonist-testosterone-treated group of irradiated rats, which had normal physiological levels of FSH; this result supports a role for endogenous FSH in suppressing spermatogonial differentiation in the latter group. The third approach involved injection of an active anti-FSH antibody for 10 d in untreated, GnRH-ant plus flutamide-treated, or GnRH-ant plus testosterone-treated irradiated rats. This was not sufficient to increase the TDI. However, flutamide given in a similar treatment schedule did increase the TDI in GnRH-ant plus testosterone-treated rats. We conclude that both testosterone and FSH individually inhibit spermatogonial differentiation after irradiation, but testosterone is a more highly potent inhibitor than is FSH.

Evaluation of single intratesticular injection of calcium chloride for nonsurgical sterilization in adult albino rats

OBJECTIVE

To investigate a method of chemical sterilization and its efficacy in adult albino rats.

METHOD

Evaluation was conducted 3 weeks after a single bilateral intratesticular injection of calcium chloride (CaCl2) at the dose of 5, 10, 15 or 20 mg per testis per 100 g body weight.

RESULTS

The significant graded diminution in relative sex organ weights, testicular androgenic enzymes like Delta5,3beta-hydroxysteroid dehydrogenase (Delta5,3beta-HSD) and 17beta-hydroxysteroid dehydrogenase (17beta-HSD), glutathione peroxidase (GPx), glutathione S-transferase (GST) and superoxide dismutase (SOD) activities, testicular content of reduced glutathione (GSH), plasma and intratesticular concentrations of testosterone, epididymal sperm count as well as significant elevation in plasma concentrations of luteinizing hormone (LH), follicle-stimulating hormone (FSH) and testicular content of malondialdehyde (MDA) were noted in all the treated groups with respect to vehicle control. There was no chronic general stress in experimental animals as indicated by insignificant changes in plasma concentrations of corticosterone, prolactin, total protein, blood urea nitrogen and fasting blood sugar level. Dose-dependent responses on testicular histopathology were recorded by noting multinucleated giant cells in seminiferous tubules, derangement of tubular architecture along with infiltration of leucocytes and appearance of fibrous tissue throughout the testicular sections. The fertility efficacy of the 10, 15 or 20 mg CaCl2-treated males was nil, proven after mating with fertile, virgin healthy females, as there were no implantation sites in each uterine horns noted by laparotomy.

CONCLUSION

Intratesticular CaCl2 injection at a specific dose might serve as a way of sterilization and may be considered as an alternative to surgical castration in male animals.

Arrest of spermatogenesis at the early meiotic stage in the small testis mutant (Smt) mice

A spontaneous mutant having small testes was found in a laboratory mouse strain of mixed origins. The testis size was 1/3-1/2 of normal size, but no significant difference was seen in body mass and weight of organs such as kidney and seminal vesicle, which are influenced by androgen. Small testis males were found to be infertile by the mating test, although formation of a vaginal plug was normally observed in their female partners. Histological and air-dried specimens revealed degeneration of zygotene or early pachytene spermatocytes and very few numbers of pachytene and diplotene spermatocytes, round and elongate spermatids and mature spermatozoa in the mutant testis. Therefore, it was concluded that spermatogenesis is disrupted at the zygotene to early pachytene stages of meiosis in the mutant males. Segregation ratios of normal and mutant males were in accord with the assumption that the small testis character is caused by an autosomal recessive mutation. This mutant may be useful for research that would contribute to the elucidation of genetic mechanisms controlling the process of spermatogenesis and as a model animal for male infertility in humans.

Role of retinoid signaling in the regulation of spermatogenesis

While the need for vitamin A for the normal progression of male germ cell differentiation has been known for many years, the molecular mechanisms underlying this requirement are poorly understood. This review will explore the aspects of the effects on spermatogenesis of dietary deprivation of vitamin A, in particular as to how they compare to the male sterility that results from the genetic ablation of function of the retinoid receptor RARalpha. The effects of other genes involved with retinoid synthesis, transport, and degradation are also considered. The possible cellular mechanisms that may be affected by the lack of retinoid signaling are discussed, in particular, cell cycle regulation and cell-cell interaction, both of which are critical for normal spermatogenesis.

An X-to-autosome retrogene is required for spermatogenesis in mice

We identified the gene carrying the juvenile spermatogonial depletion mutation (jsd), a recessive spermatogenic defect mapped to mouse chromosome 1 (refs. 1,2). We localized jsd to a 272-kb region and resequenced this area to identify the underlying mutation: a frameshift that severely truncates the predicted protein product of a 2.3-kb genomic open reading frame. This gene, Utp14b, evidently arose through reverse transcription of an mRNA from an X-linked gene and integration of the resulting cDNA into an intron of an autosomal gene, whose promoter and 5' untranslated exons are shared with Utp14b. To our knowledge, Utp14b is the first protein-coding retrogene to be linked to a recessive mammalian phenotype. The X-linked progenitor of Utp14b is the mammalian ortholog of yeast Utp14, which encodes a protein required for processing of pre-rRNA and hence for ribosome assembly. Our findings substantiate the hypothesis that mammalian spermatogenesis is supported by autosomal retrogenes that evolved from X-linked housekeeping genes to compensate for silencing of the X chromosome during male meiosis. We find that Utp14b-like retrogenes arose independently and were conserved during evolution in at least four mammalian lineages. This recurrence implies a strong selective pressure, perhaps to enable ribosome assembly in male meiotic cells.

Proliferation and differentiation of spermatogonial stem cells in the w/wv mutant mouse testis

Mutations in the dominant-white spotting (W; c-kit) and stem cell factor (Sl; SCF) genes, which encode the transmembrane tyrosine kinase receptor and its ligand, respectively, affect both the proliferation and differentiation of many types of stem cells. Almost all homozygous W or Sl mutant mice are sterile because of the lack of differentiated germ cells or spermatogonial stem cells. To characterize spermatogenesis in c-kit/SCF mutants and to understand the role of c-kit signal transduction in spermatogonial stem cells, the existence, proliferation, and differentiation of spermatogonia were examined in the W/Wv mutant mouse testis. In the present study, some of the W/Wv mutant testes completely lacked spermatogonia, and many of the remaining testes contained only a few spermatogonia. Examination of the proliferative activity of the W/Wv mutant spermatogonia by transplantation of enhanced green fluorescent protein (eGFP)-labeled W/Wv spermatogonia into the seminiferous tubules of normal SCF (W/Wv) or SCF mutant (Sl/Sld) mice demonstrated that the W/Wv spermatogonia had the ability to settle and proliferate, but not to differentiate, in the recipient seminiferous tubules. Although the germ cells in the adult W/Wv testis were c-kit-receptor protein-negative undifferentiated type A spermatogonia, the juvenile germ cells were able to differentiate into spermatogonia that expressed the c-kit-receptor protein. Furthermore, differentiated germ cells with the c-kit-receptor protein on the cell surface could be induced by GnRH antagonist treatment, even in the adult W/Wv testis. These results indicate that all the spermatogonial stem cell characteristics of settlement, proliferation, and differentiation can be demonstrated without stimulating the c-kit-receptor signal. The c-kit/SCF signal transduction system appears to be necessary for the maintenance and proliferation of differentiated c-kit receptor-positive spermatogonia but not for the initial step of spermatogonial cell differentiation.

GATA-1 testis activation region is essential for Sertoli cell-specific expression of GATA-1 gene in transgenic mouse

BACKGROUND

The erythroid transcription factor GATA-1 is also expressed in Sertoli cells of the testis. The testicular expression of GATA-1 is regulated in a developmental and spermatogenic stage-specific manner. To further clarify the regulatory mechanisms of testicular GATA-1 gene expression, we carried out transgenic reporter gene expression analyses.

RESULTS

We found that GATA-1 expression in Sertoli cells is markedly decreased concomitant with the emergence of elongated spermatids in the seminiferous tubules. Transgenic reporter mouse analyses revealed that a 15 kb GATA-1 genomic region is sufficient to recapitulate the gene expression profile in Sertoli cells. While the GATA-1 haematopoietic enhancer and the proximal first exon are included within the 15 kb genomic region, these regulatory elements are not essential for GATA-1 expression in Sertoli cells. Further analyses using deletion constructs revealed that a 1.5 kb region 5' to the GATA-1 haematopoietic enhancer is essential for gene expression in Sertoli cells and this region is referred to as the GATA-1 testis activation region.

CONCLUSION

These results thus demonstrated that the GATA-1 testis activation region is essential for Sertoli cell-specific expression of GATA-1 gene. The 15 kb genomic region is applicable and useful for the expression vector system specific for adult Sertoli cells in stage VII to IX.

Increment of murine spermatogonial cell number by gonadotropin-releasing hormone analogue is independent of stem cell factor c-kit signal

Recent studies have demonstrated that GnRH-analogues can stimulate regeneration of spermatogenesis of rats when administered after testicular damages. Although the mechanism of this phenomenon has not been elucidated yet, stem cell factor (SCF) produced by Sertoli cells was proposed to mediate the effects of GnRH-analogues on spermatogonial proliferation and/or survival. In the present study, we quantitatively evaluated the proliferation of spermatogonia and addressed whether SCF mediates the effect of GnRH-analogue on spermatogonial proliferation, using a novel approach combining spermatogonial transplantation and laser confocal microscopic observation. In the first experiment, using wild-type mice as recipients for spermatogonial transplantation, the number of donor spermatogonia per 100 Sertoli cells in each spermatogenic colony was significantly higher in the experimental group of mice treated with leuprorelin, a GnRH-agonist, than that of the control group at 4 and 5 wk after transplantation. In the second experiment, Steel/Steeldickie (Sl/Sld) mutant mice, which lack expression of membrane bound form SCF, were used as recipients. As seen in the first experiment, the number of undifferentiated spermatogonia was significantly higher in leuprorelin-treated than in the control group. Since undifferentiated spermatogonia do not express the receptor of SCF, the present study clearly demonstrates that neither membrane-bound nor secreted forms of SCF are involved in the mechanism of GnRH-analogue's effect on spermatogonial proliferation and/or survival.

Effects of Vinclozolin Administration on Sperm Production and Testosterone Biosynthetic Pathway in Adult Male Rat

The effect of vinclozolin (VCZ), used as a fungicide and known to have anti-androgenic effects on spermatogenesis and gene expression in the male rat testis was investigated. In Experiment 1, VCZ (100 mg/kg/day) or flutamide (FM, 25 mg/kg/day) was orally administered to male Holzman rats for six days. 8 days after the last administration (D8), a drastic increase in intratesticular testosterone was detected in FM (4.2-fold over control) but not in VCZ treated animals, whereas on D36 post-administration, both groups showed similar levels. Significant decreases in daily sperm production were seen in both VCZ and FM-treated rats on D36. Semiquantitative RT-PCR analysis with testicular and pituitary mRNAs on D8 revealed that LHbeta and FSHbeta mRNAs were increased in the pituitary by VCZ, as well as by FM. Among the four testicular steroidogenic enzyme genes, cytochrome P450 side chain cleavage (P450scc) and cytochrome P450 17alpha/C(17-20) lyase (P450c17) mRNAs were significantly increased, whereas 17beta-hydroxysteroid dehydrogenase type III (17betaHSD) mRNA was not changed. A significant increase in 3beta-hydroxysteroid dehydrogenase type I (3betaHSD) and a decrease in androgen receptor (AR) mRNA were observed only in FM treated rats. Immunohistochemistry demonstrated intense staining of P450scc in the interstitial cells of VCZ-treated testis on D8. In Experiment 2, hormone levels were measured at 1, 3, 6, 12 and 24 hours after VCZ (100 mg/kg) administration to Sprague-Dawley rats. Serum LH level remained constant for the first 3 hours and started to increase at 6 hrs. In contrast, serum and intratesticular testosterone levels increased 2-fold at 1 hr and maintained the level until 24 hrs. P450c17 mRNA level was 2-fold increased at all periods, whereas no obvious changes were detected in the other steroidogenic enzyme genes. Although not statistically significant, AR mRNA level increased 2-fold, 3 hrs after VCZ administration. These results indicate that VCZ affects the pituitary in a similar manner as FM, but functions differently on testicular gene expression.

Disruption of pubertal onset by exogenous testosterone and estrogen in two species of rodents

The administration of adult physiological levels of testosterone (T) and 17beta-estradiol (E(2)) to male Siberian hamsters was previously shown to delay the onset of puberty. To examine whether this is a response common to other rodents, we investigated whether exogenous steroids also alter the onset of puberty in Syrian hamsters and mice. Juvenile male Syrian hamsters and mice were implanted with Silastic capsules containing T, E(2), or cholesterol control. After 15 days, plasma, pituitaries, and testes were processed for histological analysis or measurements of gonadotropins and circulating steroid hormones. T and E(2) implants reduced testis mass and gonadotropin stores in both species and arrested spermatogenesis in Syrian hamsters. In contrast, spermatogenesis in mice was unaffected by T and only modestly affected by E(2). Although E(2) inhibited circulating follicle-stimulating hormone (FSH) in both species, T inhibited circulating FSH in mice only. Overall, our results demonstrate that the hypothalamic-pituitary-gonadal axis of each rodent species responds uniquely to T and E(2) during the pubertal transition. Despite the highly varied effects of T and E(2) in these two species, the ability of steroid hormones to disrupt the onset of puberty appears to be a feature common to many rodents.

Alterations of Gene Expression in Adult Male Rat Testis and Pituitary Shortly After Subacute Administration of the Antiandrogen Flutamide

In the course of profiling alterations of gene expression in the male reproductive system induced by anti-androgenic agents, 28 genes expressed in the testis or pituitary of adult rats were examined shortly after subacute administration of the well-known anti-androgen, flutamide (FM). FM (25 mg/kg/day) was orally administered to male rats for six days. On day 8 (D8) after the first dose of FM, intratesticular testosterone (T) levels had dramatically increased, but daily sperm production on D36 was significantly decreased. The mRNA levels of testicular and pituitary genes on D8 were measured by semiquantitative RT-PCR. Among the six testicular steroidogenic enzyme genes, the mRNAs of the P450 side chain cleavage, P450 17 alpha/C(17-20) lyase, and 3beta-hydroxysteroid dehydrogenase type I (3betaHSD) genes significantly increased, whereas 17beta-hydroxysteroid dehydrogenase type III slightly decreased. Among the three steroid receptors examined, androgen receptor (AR) and glucocorticoid receptor (GR) mRNAs were significantly down-regulated (29% and 35%, respectively) in the testis, but there was no change in estrogen receptor alpha. There were no clear changes in expression of the gonadotropin receptors and Sertoli cell specific genes, but a slight increase was observed in expression of the lactose dehydrogenase-c mRNA, a germ cell specific gene. Among the three immediate early genes, c-myc mRNA was increased approximately 1.4-fold. In the pituitary, on the other hand, mRNAs for LHbeta and FSHbeta subunits and gonadotropin releasing hormone receptor had increased significantly. These results show that subacute FM administration first affected hypothalamus/pituitary hormone gene expression, then altered gonadotropin secretion, and subsequently induced over-expression of testicular steroidogenic enzyme genes. However, the significant up-regulation of 3betaHSD and down-regulation of AR mRNAs, despite the higher level of intratesticular T, might be explained by an antagonistic action of hydroxyflutamide retained in the testis. The profiles of alterations in gene expression observed will provide important information for the screening of adult male animals for anti-androgenic chemicals.

Homeostatic regulation of germinal stem cell proliferation by the GDNF/FSH pathway

Stem cell regulatory mechanisms are difficult to study because self-renewal and production of differentiated progeny, which are both strictly controlled, occur simultaneously in these cells. To focus on the self-renewal mechanism alone, we investigated the behavior of germinal stem cells (GSCs) in progeny-deficient testes with defective GSC differentiation. In these testes, we found that the proliferation of undifferentiated spermatogonia, some of which are GSCs, was accelerated by high concentrations of glial cell line-derived neurotrophic factor (GDNF). Furthermore, we found that follicle-stimulating hormone (FSH) stimulation via homeostatic control was one of the major regulators of GDNF concentration. These results suggest that in mammalian testes, GSC proliferation and population size are regulated homeostatically by the GDNF/FSH pathway.

Restoration of spermatogenesis and fertility in azoospermic mutant mice by suppression and reelevation of testosterone followed by intracytoplasmic sperm injection

Advances in assisted reproduction techniques such as in vitro fertilization and intracytoplasmic sperm injection have made paternity possible for many patients with male infertility. However, at least some sperm or spermatids are required for these techniques to be successful, and patients incapable of producing spermatids cannot be helped. Male mice homozygous for the mutant juvenile spermatogonial depletion (jsd) gene show spermatogonial arrest and an elevated intratesticular testosterone level like many other experimental infertility models such as those with iradiation- or chemotherapy-induced testicular damage. In this category of infertile males, suppression of the testosterone level induces spermatogonial differentiation to the stage of spermatocytes but no further. In the present study with jsd mutant mice, we induced spermatogenesis first to spermatocytes and then to elongated spermatids by suppression of testosterone levels with a GnRH antagonist, Nal-Glu, at a dose of 2500 microg kg(-1) day(-1) for 4 wk and then withdrawal of Nal-Glu. Spermatids were seen in the cross-sections of seminiferous tubules in all mice treated by administration and subsequent withdrawal of Nal-Glu. Four weeks after withdrawal of Nal-Glu, some of the germ cells differentiated into elongated spermatids. Supplementation with testosterone and Nal-Glu after 4 wk of treatment with Nal-Glu alone also induced spermatogenesis similar to the induction by withdrawal of Nal-Glu. Thus, we ascribe the restoration of the differentiation of spermatocytes to spermatids to reelevation of the testosterone level. Furthermore, we successfully rescued male sterility in jsd mice by subsequent intracytoplasmic sperm injection using the elongated spermatids induced by the programmed hormone therapy.