Gonadotropins: folitropin and lutropin

Gonadotropins are glycoproteins secreted by gonadotrophs in the anterior pituitary of both women and men. In men, they are secreted constantly, while in women, they are secreted periodically and in much larger quantities. Gonadotropins regulate gametogenesis and spermatogenesis in the reproductive glands. Negative feedback from steroid sex hormones regulates the secretion of follicle-stimulating hormone (FSH) and luteinizing hormone (LH). Sex hormones suppress their secretion. Hypothalamic gonadotropin-releasing hormone also regulates FSH and LH secretion via the calcium-phosphorus complex.
Though it affects FSH and LH, their plasma concentrations vary unevenly. The testes secrete inhibin, which inhibits FSH secretion. FSH (follicle-stimulating hormone) receptors are located in the plasma membranes of ovarian follicles and testicular Sertoli cells. The secondary messenger of FSH is cAMP, with a half-life of 20 minutes. FSH stimulates the growth and maturation of ovarian follicles, ovulation, estrogen secretion, and the formation of secondary sexual characteristics. It promotes the development of testicular Sertoli cells, the biosynthesis of androgen-binding protein, which helps transport testosterone necessary for spermatogenesis to the seminiferous tubules. FSH also activates the growth of testes and seminiferous tubules, induces spermatogenesis, and promotes the synthesis of inhibin, which inhibits FSH secretion. It also stimulates the formation of estradiol in Sertoli cells.