Feedback Control of FSH Secretion in the Male Rat

Abstract

Site of feedback control of FSH secretion in the male rat was studied by measuring changes in serum LH, FSH and hypothalamic LH-RH by radioimmunoassay in rats after castration and after 500 rad X-irradiation to the testis. The rise in serum LH and FSH in castrated animals was associated with a significant fall in hypothalamic LH-RH 16 and 24 days after castration. Serum FSH rose significantly after X-irradiation without a significant change in serum LH or hypothalamic LH-RH content up to 30 days after irradiation. When pituitary halves from X-irradiated animals were incubated in vitro in the presence or absence of synthetic LH-RH, there was a significant rise in FSH (but not LH) released in the incubation medium in the absence of added LH-RH. The response of the pituitaries to LH-RH was, however, not different between control and irradiated rats. It is concluded that the testicular FSH-inhibitory substance acts predominantly at the pituitary gland on the LH-RH independent release of FSH.

Current Concepts of Follicle-Stimulating Hormone Receptor Gene Regulation1

“…Initially, during the perinatal period, FSH induces Sertoli cell proliferation and establishes the final Sertoli cell number that will ultimately determine spermatogenic output, whereas later in development, FSH stimulates Sertoli cell transcriptional and metabolic activities, which contribute to the hormonal and nutritional environment necessary for germ cell survival and development [26][27][28][29][30][31][32][33][34][35]. In both males and females, FSH induces hormonal signals that return to the pituitary and hypothalamus as part of the feedback mechanism upholding the endocrine balance in the reproductive axis [36][37][38][39][40][41]. …”