Effect of copulatory stimuli on incidence of ovulation and on serum luteinizing hormone in the cat.

Abstract

The relationship among the number of copulatory stimuli, the incidence of ovulation, and the pituitary release of LH was studied in the female cat (queen), an induced or reflex-ovulating species. Estrual queens were mated with a male either once during estrus (on day 1, 2, 3, or 4) or three times at 4-h intervals in a single day of estrus (on day 1, 2, or 3). Laparoscopy was used to examine the ovaries, initially to determine the numbers of preovulatory follicles and later to count corpora lutea. Blood samples were obtained serially from cats in each mating group, and sera were analyzed for LH. The day of estrus on which mating occurred, estrus duration, and follicle numbers had no effect on the proportion of animals ovulating. A single mating resulted in fewer queens ovulating per group (10 of 48 animals) than three matings on a single day (30 of 36). After copulation, LH was elevated only in animals later confirmed to ovulate. LH response in ovulating queens varied among individuals but, when averaged, appeared to be greater and more prolonged in multiple mated vs. single mated animals. These data indicate that the reflex-ovulating cate does not always ovulate after a single copulatory stimulus because of a failure of LH release. The frequency of coital stimulation apparently plays a major role in influencing the proportion of animals ovulating, with multiple copulation apparently enhancing the pituitary release of LH.