ПРОЛАКТИН, ЧЕЛОВЕКА

The hormone from the adenohypophysis, consisting of single chain of 198 amino acid residues with three disulphide linkages that stimulates lactation by the mammary glands, in conjunction with the effects of estrogen, progesterone, and oxytocin. Prolactin secretion is normally suppressed by the hypothalamic prolactin inhibitory factor until after parturition. In birds stimulates secretion of crop milk by the crop glands.

Prolactin is glycosylated.

Human prolactin is similar in structure to human growth hormone, and both are good lactogens. In women, prolactin acts with other hormones on the mammary gland during pregnancy to develop lactation and after birth to maintain it. Hyperprolactinemia causes impotence in men and amenorrhea and infertility in women. Chronically elevated levels of circulating prolactin are associated with suppression of 17-β-estradiol and testosterone production in the ovaries and testes.
Prolactin serum levels increase during pregnancy and breast-feeding, at least immediately after the birth. In both men and women, prolactin increases after sleep starts, continues to increase during the night, and increases markedly during stress. Prolactin release is episodic during the day. More than 20 hormones and neurotransmitters affect prolactin production, but the dominant physiological control is primarily negative, mediated by dopamine from the hypothalamus. Dopaminergic agonists inhibit prolactin release and antagonists, such as the antipsychotic drugs, increase release.

Prolactin (PRL), a hormone secreted by the anterior pituitary,was discovered in 1928. It is a 198-residue polypeptidewith general structural features similar to those of GH.PRL stimulates lactation of parturition.