EFFECT OF LUTEINIZING HORMONE RELEASING HORMONE ON PLASMA LEVELS OF LUTEINIZING HORMONE, OESTRADIOL AND TESTOSTERONE IN THE MALE DOG

An injection of luteinizing hormone releasing hormone (LH-RH) increased plasma LH and testosterone concentrations in the male dog, but no significant increase in plasma oestradiol-17beta levels was observed. Repeated injections of LH-RH produced an increase in plasma LH levels but there was a progressive decline in the response with each injection. The concentration of plasma testosterone reached a maximum within 40 min of the first injection of LH-RH and remained constant thereafter while plasma oestradiol concentration gradually increased with successive injections of LH-RH.