Role of the corpus luteum of pregnancy in controlling pituitary gonadotrophin secretion during the early post-partum period in the ewe

Abstract

No difference was found between 5 intact ewes and 5 ewes from which the CL had been excised at Day 70 of pregnancy in the plasma concentration of progesterone at Day 140, and concentrations of progesterone remained below 0.2 ng/ml during the first 20 days post partum. Plasma concentrations of LH, frequency and amplitude of LH pulses were low at Day 140 and increased considerably, particularly in the CL-excised ewes, as early as Day 5 post partum. No significant differences were found between the two groups of ewes in the mean plasma concentrations of FSH for any of the 5 stages examined. Taken together, these results suggest that some factor, other than progesterone, associated with the CL of pregnancy is involved in the inhibition of pulsatile LH secretion during the early post-partum period.