Seasonal reproduction in the mongoose, Herpestes auropunctatus: III. Regulation of gonadotropin secretion in the male

The seasonal regulation of gonadotropin secretion in the male mongoose was investigated by evaluating in vitro responsiveness of anterior pituitaries to gonadotropin releasing hormone (GnRH) and by evaluating postcastration gonadotropin responses in vitro and in vivo during the breeding and inactive seasons. The relative increase of luteinizing hormone (LH) from in vitro GnRH-stimulated anterior pituitaries was significantly greater during the active season than during the inactive season. The reduced responsiveness during the inactive season was related to an increase in the negative feedback actions of the testes at the hypophyseal level. In vitro follicle stimulating hormone (FSH) secretion from GnRH-treated anterior pituitaries was not significantly affected by season; however, a more potent negative feedback effect of the testes on basal FSH release was apparent during the inactive season. The postcastration serum LH response was more rapid during the active season than during the inactive season, whereas the postcastration serum FSH response was not affected by season.