Abstract
The concentration of plasma prolactin during the period of premature ovulation induced by human chorionic gonadotropin (HCG) or luteinizing hormone releasing hormone (LH-RH) in diestrous rats was determined at 3 hr intervals from 1700 hr on the day of diestrus (day 0) to 2300 hr on the day of proestrus (day 1). Premature ovulation was induced by either a single injection of 10 IU HCG at 1700 hr on day 0 or three injections of 1 μg LH-RH at 1 hr intervals from 1700 to 1900 hr on day 0 In saline-treated controls, the concentration of prolactin iri plasma was low during diestrus but increased on the afternoon of proestrus with a peak value at 1700 hr, followed by an abrupt decline at 2300 hr on the same day. However, there was no significant rise in the plasma prolactin level throughout the period of observation in HCG-treated rats. In the LH-RH-treated group, the prolactin level in plasma did not change until 1100 hr on day 1, but significantly increased at 1400 hr on the same day then declined by 2300 hr, though no significant difference was observed at any time when compared to HCG-treated rats.
These results indicate that no prolactin surge occurred during the period of premature ovulation.
