Stimulation of uterine prolactin secretion by human chorionic gonadotropin and progesterone in the cynomolgus monkey.

The ovulating cynomolgus monkey secretes immunoreactive prolactin (PRL) into the uterine cavity. Consistent with human endometrial explant data, uterine PRL is undetectable in the early secretory phase, then increases from the mid to late secretory phase, peaking premenstrually. The anovulatory monkey does not produce detectable uterine PRL. Human chorionic gonadotropin given repeatedly fails to induce PRL secretion in anovulatory monkeys but prolongs the luteal phase and thereby PRL secretion in ovulatory monkeys. Progesterone (P) induces PRL secretion in anovulatory monkeys after estrogen priming with a time delay of several days, indicating probable de novo synthesis. P appears to be an important stimulating factor in the control of uterine PRL secretion.