SERUM LUTEINIZING-HORMONE AND OVULATORY RESPONSE TO LUTEINIZING-HORMONE-RELEASING HORMONE IN THE ESTROUS AND ANESTROUS DOMESTIC CAT

Abstract

A heterologous double antibody radioimmunoassay was developed to measure changes in serum luteinizing hormone (LH) concentrations in estrous and anestrous queens (female domestic cats), following a single injection of varying doses (0-25 .mu.g) of luteinizing hormone-releasing hormone (LH-RH). No increase in serum LH was detected in any of the estrous or anestrous queens following a single saline injection. Treatment with LH-RH resulted in a sharp increase in serum LH concentration in both estrous and anestrous queens. Ovulations as observed by the presence of corpora lutea at laparoscopy occurred in none of 4, 1 of 4, 2 of 4 and 4 of 4 estrous queens receiving 0, 5, 10 or 25 .mu.g of LH-RH, respectively. Mean serum LH concentration of the ovulating queens was maintained at a higher level and did not return to basal level at the same time as that of nonovulating queens. LH-RH can cause release of LH in both estrous and anestrous queens and induce ovulation in the estrous cat; the magnitude of LH response is influenced by the stage of the reproductive cycle and the duration during which LH is maintained above basal level may play a significant role in ovulation induction in this coitus-induced ovulatory species.