Gonadotropins

Description

The gonadotropins, FSH and LH, are large glycoproteins released by the anterior pituitary on stimulation from GnRH produced by the hypothalamus. Both FSH and LH consist of two noncovalently associated α and β subunits. The α subunits both contain 92 amino acids and are identical in both hormones, whereas the β subunit in LH consists of 121 residues and 111 residues in FSH, with the β subunits being dissimilar. Thus, the β subunit gives each hormone its specific function.

Biological Functions

Both LH and FSH are referred to as gonadotropins, because they act on the male and female gonads, which results in the production of the sex steroids testosterone and estradiol, respectively. In the female, FSH and LH act in concert in regulating ovarian function: egg maturation, ovulation, and transformation of the ruptured follicle into the corpus luteum. In males, spermatogenesis is dependent on these two hormones. Specifically, FSH in females facilitates the maturation of ovarian follicle cells and their secretion of estradiol, whereas in males, it stimulates the maturation of sperm in the testes. In females, LH promotes ovulation, formation of the corpus luteum, and progesterone secretion; in males, it enables the secretion of testosterone from the testes.