Effect of Prostaglandin F2α on the Number of LH Receptors in Ovine Corpora Lutea

Abstract

An experiment was conducted to determine if injections of prostaglandin (PG) F2α influenced the number of receptors for LH in ovine luteal tissue and to compare the time course of change in the numbers of LH receptors and progesterone secretion. Ewes on Day 9 of the estrous cycle were given 2 injections of PGF2α-tham salt (6.7 mg, i.m.) at 4 h intervals. Corpora lutea were removed from each of 6 ewes at 2.5, 7.5, and 22.5 h after the initial injection of PGF2α and from 6 control ewes on Day 10 of the cycle. Jugular blood samples for analysis of progesterone were collected at 20 min intervals for 1 h prior to treatment and at 0.5, 1 or 2 h intervals in ewes in which corpora lutea were collected at 2.5, 7.5 and 22.5 h after injection of PGF2α, respectively. Luteal weight, luteal progesterone concentrations and total number of luteal LH receptors and the number of receptors occupied by endogenous LH were determined.