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.
