Stimulation of pituitary and testicular functions with LH-RH agonist or pulsatile LH-RH treatment in the rhesus monkey during the non-breeding season.

Out-of-season male rhesus monkeys were used to compare the effectiveness of pulsatile treatment with LH-RH and administration of LH-RH agonist on testicular function. Treatment with LH-RH agonist (1.0 microgram Hoe 766/day) for 11 weeks resulted in partial stimulation of pituitary and testicular functions. The pituitary LH response to the agonist increased during treatment. Testosterone levels were stimulated to within the normal range and 2 of the 4 treated monkeys produced ejaculates, but sperm counts were below normal. Pulsatile treatment with LH-RH (100 ng every 96 min for 7 days alternating with LH-RH agonist treatment for 7 days) in 2 monkeys induced full testicular activity after 7 weeks. Ejaculations were induced at a time when the rhesus monkey is normally sexually inactive. Seminal characteristics at the end of treatment were similar to values in the normal breeding season. In samples collected from one monkey over a 24-h period before treatment there were no LH spikes and very low testosterone levels. During pulsatile LH-RH treatment distinct LH and testosterone spikes occurred, comparable to those in the breeding season.