Changes in histology, protein expression, and autophagy in dairy goat testes during nonbreeding season†

Seasonal reproduction contributes to increased chances of offspring survival in some animals. Dairy goats are seasonal breeding mammals. In this study, adult male Guanzhong dairy goats (10-12 months old) were used. Testis size, semen quality, hormone level, apoptosis of germ cells, and autophagy of Sertoli cells were analyzed in dairy goats during the breeding (October) and nonbreeding (April) seasons. We found that, during the nonbreeding season for dairy goats, semen quality, follicle-stimulating hormone (FSH) levels, and testosterone levels were reduced, and the number of apoptotic germ cells increased. The proliferation with decrease activity of germ cells in dairy goat during the nonbreeding season was significantly affected. However, the testis size did not change seasonally. Interestingly, Sertoli cell autophagy was more active during the nonbreeding season. The expression levels of FSH receptor, wilms tumor 1, androgen binding protein, glial cell derived neurotrophic factor, and stem cell factor decreased in dairy goats during the nonbreeding season. In summary, our results indicate that spermatogenesis in dairy goats during the nonbreeding season was not completely arrested. In addition, germ cell apoptosis and the morphology of Sertoli cells considerably changed in dairy goats during the nonbreeding season. Sertoli cell autophagy is involved in the seasonal regulation of spermatogenesis in dairy goats. These findings provide key insights into the fertility and spermatogenesis of seasonal breeding animals.