Effect of Naloxone on the Pulsatile Secretion of Luteinizing Hormone in Gonadectomized Male and Female Ferrets Before and After Oestradiol Replacement

Abstract

Intravenous infusions of the opioid receptor antagonist, naloxone, caused a significant rise in luteinizing hormone (LH) pulse frequency in male and female ferrets which had been gonadectomized 10 days earlier while in breeding condition; mean LH concentrations and LH pulse amplitudes were not affected. By contrast, naloxone failed to stimulate LH pulse frequency, or other LH parameters in gonadectomized ferrets of either sex which received daily injections of a low dose of oestradiol. Our results for the ferret, in which the female is an induced ovulator, resemble those previously obtained in another induced ovulator, the rabbit. They contrast, however, with the results of numerous studies using spontaneously ovulating species in which sex steroids, if anything, facilitate the ability of naloxone to stimulate LH secretion. Copyright © 1990, Wiley Blackwell. All rights reserved