Effects of induction of parturition by administration of a prostaglandin F 2α analogue in rabbits: possible modification of prolactin, LH and FSH secretion patterns

Abstract

The influence of inducing parturition by the administration of prostaglandin F 2α (PGF 2α) on prolactin (PRL), luteinizing hormone (LH) and follicle-stimulating hormone (FSH) secretion patterns during the last days of pregnancy (Days 29–31) and lactation (Days 1–28) was studied in 20 doe rabbits of the California breed. Animals were allocated to receive either a single intramuscular injection of 50 μg of a PGF 2α, analogue (treated group) or 2 ml saline (control group) on Day 29 of pregnancy. All females were mated on Day 7 post-partum. The conception rate in treated and control animals was 100% and 90%, respectively. No influence of the prostaglandin treatment on mean plasma PRL and FSH concentrations was observed. High plasma PRL levels were detected in both groups from Day 7 to 19 of lactation. PRL levels decreased in all rabbits from Day 19 to 28 of lactation. Prostaglandin F 2α-treatcd animals showed low plasma LH concentrations after treatment during the entire period studied. High mean FSH concentrations were found in both groups from Day 3 to 5 and 19 to 28 of lactation, and low levels from Day 7 to 16 of lactation. The results suggest that the induction of parturition by PGF 2α can influence the final stage of pregnancy and lactation period due to changes in plasma LH levels, and has no effect on mean plasma PRL and FSH levels during these same periods.