2011 年 60 巻 1 号 p. 47-56
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.