Stimulation of Ovulation in the Rabbit Triggered by Synthetic LRF

Results in previous experiments led to the assumption that if electr ical stimulation of the hypothalamus in the rabbit stimulates the release of LH-releasing factor (LRF), which in turn induces the secretion of LH and FSH leading to ovulation in the constant estrous rabbit, then peripheral injection of LRF alone with no other hormonal treatment should trigger ovulation in the rabbit. It was determined in a study of 30 rabbits that a single iv injection of synthetic LRF with no other hormonal pretreatment regularly stimulated ovulation. The minimal dose active in all animals appeared to be 1 mcg (200 ng/kg body weight). No ovulation was ever observed in the control animals injected with saline. At all doses (1, 10, and 50 mcg), it appeared that LRF was more active when administered as a single injection than over a 30-minut e iv infusion. An increasing number of ova were released as the dose of injected LRF increased.