Hormonal Regulation of Male Reproductive System (Human)

The male reproductive system is synchronized by the production, stimulation, and feedback of specific hormones.

At a Glance

·         GnRH is made in the hypothalamus and movements to the pituitary where it stimulates FSH and LH secretion.

·         FSH is necessary for sperm maturation.

·         LH binds to Leydig cells to stimulate testosterone secretion and androgen production.

·         Testosterone stimulates sex drive.

·         Inhibin inhibit the secretion of FSH and GnRH. 

Key Function

A major part of the control of sexual functions in both the male and the female begins with secretion of gonadotropin-releasing hormone (GnRH) by the hypothalamus. This hormone in turn stimulates the anterior pituitary gland to secrete two other hormones called gonadotropic hormones: (1) luteinizing hormone (LH) and (2) follicle-stimulating hormone (FSH). In turn, LH is the primary stimulus for the secretion of testosterone by the testes, and FSH mainly stimulates spermatogenesis.

Hormone control system of human is complex enough. Beginning of spermatogenesis happens at puberty due to the interaction of the hypothalamus, pituitary gland, and Leydig cells. Absence of pituitary gland, spermatogenesis can still be started by follicle-stimulating hormone (FSH) and testosterone.

Figure: Regulation of the hypothalamic-pituitary testicular axis in males. Stimulatory effects are shown by (+) and negative feedback inhibitory effects are shown by(-).

 Act of Hormones in Human Male Reproduction

Gonadotropin-Releasing Hormone: GnRH is secreted intermittently a few minutes at a time once every 1 to 3 hours. Actually it made in the pre-optic area of the hypothalamus before migrant to the pituitary gland. There it stimulates the synthesis and secretion of the gonadotropins, FSH and LH.

Follicle-Stimulating Hormone: Follicle-stimulating hormone (FSH) is released by the anterior pituitary gland. Its presence in males is essential for the maturation of spermatozoa. The production of androgen-binding protein by Sertoli cells and the formation of the blood-testis barrier bothe are estemulated by FSH.

Luteinizing Hormone: Luteinizing hormone (LH) is released by the anterior pituitary gland. LH binds to receptors on Leydig cells In  testes. This Leydig cells stimulates the synthesis and secretion of testosterone.

Testosterone: Testosterone is secreted by the interstitial cells of Leydig in the testes, but only when they are stimulated by LH from the anterior pituitary gland. Besides, the quantity of testosterone secreted increases approximately in direct proportion to the amount of LH available. Mature Leydig cells are generally found in a child’s testes for a few weeks after birth. Then it be missing until after the age of about 10 years. Testosterone also gives a negative signal to anterior pituitary to control its secretion

Inhibin: Inhibin is secreted by the Sertoli cells and acts to decrease the levels of FSH. The hormone is released into the convention when the sperm count is too high.