The effects of gonadectomy and oestradiol-17 beta on pituitary responsiveness to LH-RH in the adult male marmoset (Callithrix jacchus).

Exogenous luteinizing hormone-releasing hormone (LH-RH) administered in a wide range of doses (0.2-25 micrograms) to intact male marmoset monkeys induced a marked increased in plasma luteinizing hormone (LH) concentrations. Maximum LH concentrations achieved after injection of LH-RH occurred progressively later as the dosage increased. Bilateral orchidectomy sigificantly enhanced pituitary responsiveness to a standard dose (2.0 microgram) of LH-RH, whereas the introduction of oestradiol-17 beta implants effectively inhibited the responses. LH-RH-induced LH release after gonadectomy (with and without oestradiol-17 beta treatment) was similar in males and females. The use of marmosets for appropriate investigation into the physiological role of LH-RH in controlling LH secretion in primates is proposed.