Effect of Copulation on the Release of Pituitary Gonadotropins in Male and Female Rats

Abstract

The effect of copulation on the release of pituitary LH and FSH was studied in male and female rats. Plasma LH significantly increased 5-10 min post coitum in both sexes and remained high during the first hour. After 2 hr values dropped to normal levels. Also, in spayed rats pretreated with estrogen-progesterone an increase in plasma LH was found. Pituitary LH concentration 1 hr after copulation showed a decrease of more than 50% as compared with the controls, but after 4 hr no difference was detected. Ovarian ascorbic acid depletion, indicative of endogenous liberation of LH, was observed 1 hr post coitum. A slight but not significant increase in pituitary FSH concentration was found 1 hr after coitus in male and female rats and a significant increase was observed in males at 4 hr. No changes in plasma FSH were detected. Vaginal stimulation with a glass rod in the proestrous or estrous rat did not induce changes in ovarian ascorbic acid concentration nor in pituitary LH and FSH content. (Endocrinology79: 49, 1966)