Adult male reproductive hormonal regulation operates through the hypothalamic-pituitary-gonadal axis, in which pulsatile hypothalamic GnRH stimulates anterior pituitary release of LH and FSH, LH binds testicular Leydig cell receptors to activate a cAMP/protein kinase pathway that converts cholesterol to testosterone, and testosterone acts locally within Sertoli cells (bound by androgen-binding protein) to support spermatogenesis. This axis is regulated by negative feedback, notably inhibin secreted by Sertoli cells suppressing anterior pituitary gonadotropin output, while testosterone released into peripheral circulation is converted by 5α-reductase into dihydrotestosterone (DHT), a distinct downstream androgen with its own physiological and pharmacological significance. The framework distinguishes carrier/binding proteins produced locally within target tissues (e.g., androgen-binding protein) from circulating binding globulins produced by the liver (e.g., sex hormone-binding globulin), a distinction paralleled in other endocrine binding-protein systems.
Adult male reproductive hormonal regulation operates through the hypothalamic-pituitary-gonadal axis, in which pulsatile hypothalamic GnRH stimulates anterior pituitary release of LH and FSH, LH bind…