Postcopulatory Mammary Gland Secretion in Rats

Hormonal changes occur in female mammals as a consequence of stimuli derived from mating. In rats, a rise in the plasma concentration of LH occurs within 5–10 min after coitus, and a slight rise in the FSH content of the pituitary is seen 1 hr after copulation 1. Pituitary LTH falls within 30 min after cervical stimulation 2, whereas plasma progesterone rises 24 hr after mating 3.Despite the potentially mammotropic effects of these hormones 4, no changes in rat mammary tissue in the period shortly following mating have been reported. The present study was undertaken to investigate the effects of various levels of copulatory activity on mammary secretion in female rats during the first 5 days following coitus.Materials and Methods. Adult virgin Sprague-Dawley rats (at least 90 and less than 150 days old) were purchased from Berkeley Pacific Laboratories, Berkeley, California. The females were housed in individual cages, and the colony was maintained on a reversed light-dark cycle, in a windowless room, wit...