Effect of short period vasectomy on FSH, LH, inhibin and testosterone secretions, and sperm motility in adult male rats.

The present study was undertaken to clarify changes in secretions of FSH, LH, inhibin and testosterone, and sperm motility after bilateral vasectomy in adult male rats. Bilateral vasectomy was created surgically (treated group) and intact rats were used as control (control group). On days 3, 5, 7, 14, 30, 60, and 90 after surgery, plasma concentrations of FSH, LH, inhibin, and testosterone were measured by radioimmunoassay, and sperm motility characteristics were measured by computer-assisted sperm analysis (CASA). The results show that weights of epididymides significantly increased in vasectomized rats as compared to control rats. Histologically, damage to spermatogenesis was observed in vasectomized rats. Multinucleated giant cells were observed in the lumen of some seminiferous tubules, and there were degenerative spermatids in the epididymides of vasectomized rats. Plasma levels of LH, FSH, and testosterone only decreased on day 3 after vasectomy; however, plasma levels of ir-inhibin significantly increased on day 3 after vasectomy. In addition, the sperm motility parameters, straight-line velocity, curvilinear velocity, deviation of the sperm head from the mean trajectory and the maximum amplitude of lateral head displacement were decreased from day 60 after vasectomy. These results suggest that vasectomy reduces sperm motility starting from day 60 after vasectomy, and early bilateral vasectomy does not strongly affect the endocrine function of the testis, though it may result in damage to spermatogenesis in vasectomized rats.

Effects of acute restraint stress on sperm motility and secretion of pituitary, adrenocortical and gonadal hormones in adult male rats.

The effects of acute restraint stress on sperm motility and reproductive endocrinology were investigated in adult rats. Sperm motility was determined by computer-assisted sperm analysis. Acute restraint stress reduced sperm motility starting after 30 min, and the sperm motility parameters, percentage of motile spermatozoa (%), straight-line velocity, curvilinear velocity, deviation of the sperm head from the mean trajectory and the maximum amplitude of lateral head displacement decreased. It also induced a significant elevation in plasma adrenocorticotropic hormone, prolactin, corticosterone and progesterone and decreased follicle-stimulating hormone, luteinizing hormone, testosterone and immunoreactive (ir-) inhibin. These results clearly demonstrated that the acute restraint stress rapidly suppressed sperm motility and increased the activity of the hypothalamus-pituitary-adrenal axis, whereas it disturbed hypothalamus- pituitary-gonadal axis activity.

Effects of experimental cryptorchidism on sperm motility and testicular endocrinology in adult male rats.

The effect of induced cryptorchidism on testicular function and sperm motility was investigated. Bilateral cryptorchidism was created surgically in adult male rats (treated group), and sham-operated rats were used as a control group. Five rats from each group were sacrificed on days 1, 3, 5, and 7 after surgery. The percentage of motile spermatozoa began to decrease 1 day after the operation, followed by an abrupt decline 3 and 5 days later in cryptorchid rats. Furthermore, there were significant decreases in the other sperm motility parameters 5 days after inducement of cryptorchidism. In cryptorchid rats, plasma concentrations of LH, FSH, testosterone, and inhibin B were significantly lower than in the control group 1 day after the operation. Thereafter, plasma concentrations of LH, FSH, and testosterone gradually increased in the cryptorchid rats. On the other hand, plasma concentrations of inhibin B showed a further decline from day 3 after the operation onward. Concentrations of immunoreactive (ir)-inhibin, but not testosterone, in testicular interstitial fluid were remarkably increased until 3 days after surgery in the cryptorchid rats, and declined thereafter. Testicular response to human chorionic gonadotropin (hCG) for testosterone release was decreased in the cryptorchid rats compared with the control rats, indicating that heat stress to testes resulted in a reduction of the activity of Leydig cells and Sertoli cells. These results clearly indicate that heat stress to the testes resulted in a significant reduction of sperm activity within 3 days, and this was followed by changes in testicular endocrine function.

Effects of bilateral efferent duct ligation on sperm motility and secretion of FSH, LH, inhibin, and testosterone in adult male rats.

Effects of bilateral efferent duct ligation (EDL) on sperm motility and testicular endocrinology were investigated in adult male rats. Bilateral EDL was created surgically in adult male rats (EDL group) and shamoperated rats were used as control (control group). Five rats from each group were killed on d 3, 5, 7, 14, and 35 after the surgery. The sperm motility parameters were determined by a computer-assisted sperm analysis system using sperm collected from the cauda epididymis. Concentrations of spermatozoa in epididymis and testis were counted. The motility of sperm decreased remarkably in EDL rats compared with controls on 5 d after the operation. Four sperm motility parameters-straight velocity (VSL), deviation of the sperm head from the mean trajectory (ALH, mean), the maximum amplitude of lateral head displacement (ALH, max) and curvilinear velocity (VCL)-increased on 3 d after the operation, and followed by a subsequent decline 5 and 7 d later. Concentrations of sperm significantly decreased in both testes and epididymis from 3 and 5 d after the operation. Plasma concentrations of FSH and LH increased significantly in EDL rats from 5 and 7 d after the operation, whereas plasma concentrations of immunoreactive (ir)-inhibin, inhibin B, and testosterone decreased. Testicular content of irinhibin showed an initial increase on 3 d after the operation, followed by a subsequent decline to levels significantly below controls by d 7 postoperation. On the other hand, testicular contents of testosterone were significantly higher in the EDL group than the control group on d 7-35 after the operation, whereas circulating levels of testosterone remained low. In the EDL testes, marked degenerative changes in the Sertoli cells and spermatogonia were observed, whereas Leydig cells showed clear hyperplasia. These results demonstrated that bilateral EDL induced a rapid reduction of sperm motility parameters during a short time. Present results also suggest that EDL first induces impairment of Sertoli cells function and this leads to reduction of sperm activity and secretion of inhibins. On the other hand, circulating levels of testosterone reduced after EDL and this leads to hypersecretion of LH. A large amount of LH resulted in a stimulation of Leydig cells hyperplasia.

Immunolocalization of steroidogenic enzymes in the fetal, neonatal and adult testis of the Shiba goat.

The localizations of steroidogenic enzymes (P450scc, 3 beta HSD, P450c17 and P450arom) in testes of Shiba goats were investigated by immunohistochemistry. P450scc, 3 beta HSD, P450c17 and P450arom were detected in all Leydig cells of adults. P450scc and P450c17 were observed in most Leydig cells in the fetus (90 days) and neonate (15 days). 3 beta HSD and P450arom were found in some Leydig cells of the fetus with weak immunostaining but the numbers of immunopositive Leydig cells and intense immunostaining were increased in Leydig cells of the neonate. These results suggest that Shiba goat testes have the ability to synthesize progestin, androgen and estrogen in the fetus, neonate and adult, and synthesis of these steroid hormones showed an age-related rise.

Immunolocalization of inhibin/activin subunits in the shiba goat fetal, neonatal, and adult testes.

The objective of this study was to investigate the cellular immunolocalization of inhibin alpha and inhibin/activin (betaA and betaB) subunits in the fetal, neonatal and adult testes of Shiba goats. The testes were obtained from a fetus at 90 days, a neonate at 15 days, and two adult Shiba goats (both of 3 years old). The sections of testes were immunostained by the avidin-biotin-peroxidase complex method (ABC) using polyclonal antisera raised against porcine inhibin alpha, inhibin/activin betaA, and inhibin/activin betaB. Inhibin alpha and inhibin/activin (betaA and betaB) subunits were expressed in Leydig cells, but not in the Sertoli cells of the fetus with a weak immunostaining. An increase in the number of positive cells and a more intense immunohistochemical signal for inhibin alpha and inhibin/activin (betaA and betaB) subunits were observed in the Leydig cells of neonatal testes. Moreover, inhibin alpha, betaA, and betaB subunits were expressed in the Sertoli cells and Leydig cells of adult testes, respectively. These results suggest that Shiba goats testes have the ability to synthesize inhibins in the fetus, neonate, and adult, and the cellular localization of inhibin/activin subunits showed age-related changes in fetal, neonatal, and adult testes of Shiba goats.

Immunolocalization of nerve growth factor (NGF) and its receptors (TrkA and p75LNGFR) in the reproductive organs of Shiba goats.

The objective of this study was to determine the immunolocalization of NGF and its receptors (TrkA and p75LNGFR) in the reproductive tract of the Japanese Shiba goats. Five adult goats were used in this study and sections of ovaries, uteri and oviducts were immunostained by the avidin-biotin-peroxidase complex method (ABC). The results showed that NGF and its receptors (TrkA and p75LNGFR) were expressed in granulosa cells, theca cells, interstitial cells and lutein cells in ovaries. Immunoreactions for NGF, TrkA and p75LNGFR were also detectable in epithelial cells and muscle cells of the ampulla and isthmus of the oviduct, and in epithelial cells and uterine glands of the uterus. These results strongly suggest autocrine and paracrine regulation of reproductive function by NGF in the reproductive tract of female Shiba goats.

Immunolocalization of steroidogenic enzymes in the corpus luteum and placenta of the Japanese Shiba goat.

In this study, we performed immunohistochemistry of cholesterol side-chain cleavage cytochrome P450 (P450scc), 3beta-hydroxysteroid dehydrogenase (3betaHSD), cytochrome 17alpha-hydroxylase P450 (P450c17), and cytochrome P450 aromatase (P450arom) in the corpus luteum and placenta of Shiba goats. The aim was to clarify the steroidogenic capability of the corpus luteum and placenta of Shiba goats. Ovaries containing corpora lutea were obtained from four adult Shiba goats during the luteal phase (day10; n=2) and pregnancy (90 and 120 days of gestation). Placenta was obtained from one Shiba goat on day 120 of gestation. The sections of the ovaries and placentae were immunostained using the avidin-biotin-peroxidase complex method (ABC) with polyclonal antibodies generated against steroidogenic enzymes of mammalian origin. All luteal cells expressed P450scc, 3betaHSD, P450c17 and P450arom. The distribution of P450scc, 3betaHSD, P450c17 and P450arom were not different during the luteal phase and pregnancy. P450arom showed a weak positive staining in late pregnancy (120 days). In addition, immunoreactions for P450c17 and P450arom were observed in syncytiotrophoblast of the placenta of one Shiba goat. These results indicate that, in Shiba goats, corpus luteum is not only an important source of progesterone but also has the ability to synthesize androgen and estrogen during the luteal phase and pregnancy. Also the placenta has the ability to synthesize androgen and estrogen in late pregnancy.

Inhibin B regulating follicle-stimulating hormone secretion during testicular recrudescence in the male golden hamster.

In the present study, to clarify whether inhibin affects follicle-stimulating hormone (FSH) secretion in the recrudescence of the male golden hamster, we used a recently developed specific enzyme-linked immunosorbent assay (ELISA) in order to measure 2 forms of inhibin molecules: inhibin B and inhibin pro-alphaC. In addition, we used the radioimmunoassay (RIA) to measure immunoreactive (ir-)inhibin, FSH, luteinizing hormone (LH), and testosterone. And finally, we used the proliferating cell nuclear antigen (PCNA) and computer-assisted sperm motion analysis (CASA) methods to ascertain how well spermatogenesis and sperm motility recover from the photoinhibition caused by exposure to a short-day (SD; 10-hour light: 14-hour dark) photoperiod. Animals were exposed to SD for 15 weeks, and then their testes were checked carefully and found to be completely regressed. Thereafter, those animals were transported to a long-day (LD; 14-hour light: 10-hour dark) photoperiod. Sampling was carried out at weeks 0 (exposed SD 15 weeks), 1, 2, 4, 6, 8, and 10. Plasma FSH rapidly increased and reached peak levels 2 weeks after transferral to the LD photoperiod and then declined to normal LD levels at week 6. Circulating ir-inhibin, inhibin B, and inhibin pro-alphaC rose to normal LD levels by week 4. A highly significant inverse correlation was observed between plasma FSH and inhibin B but not between FSH and either ir-inhibin or inhibin pro-alphaC. Plasma testosterone recovered to normal LD levels within 1 week. Sperm motility parameters were low until week 2 and recovered to normal LD levels from weeks 4 to 10. PCNA-labeled cells were confined to the spermatogenic cells of the seminiferous tubules, though Leydig and Sertoli cell nuclei were never stained for PCNA during the period studied. The number of pachytene spermatocytes and the diameter of seminiferous tubules increased in a time-dependent manner after transferral from SD to LD. In conclusion, these results suggest that 1) secretion of inhibin B may be stimulated by an early rise in FSH; 2) inhibin B suppresses FSH secretion from weeks 2 to 10, after transferral to the LD photoperiod; and 3) testes recrudescence is based on the increase in the number of sperm cells instead of the increase in the number of Sertoli and Leydig cells of the male golden hamster.