Ergocornine blockade of the surge of prolactin at proestrus failed to block ovulation in cycling rats.

Abstract

SummaryA study was made of the effects of ergocornine methanesulfonate (ECO) administered to normal cycling rats on the afternoon (16.30 hr) of D2 (day before PE) and on the morning (10.30 hr) of PE on prolactin content and concentration of the pituitary gland and on ovulation.Pituitary prolactin content and concentration on the afternoon of PE in the animals treated with ECO were about 3 times higher than those obtained in the saline-treated control animals. When animals treated with ECO were killed on the morning of estrus, the level of prolactin content and concentration was very high and the level was not significantly different from that obtained in the saline-treated control animals killed at the same stages of the estrous cycle.Ovulation occurred in 5 out of 6 animals treated with ECO. No significant difference was obtained in the average number of ova shed between the ECO treated animals and the saline-treated controls.A possible physiological role of prolactin release around the critical period w...