μ-Opioid agonist-stimulated [35S]GTPγS binding in guinea pig hypothalamus:: effects of estrogen

mu-Opioid receptors play a critical role in the regulation of the female reproductive cycle, and estrogen modulates the coupling of mu-opioid receptors to a potassium channel in the basal hypothalamus (BH) of the female guinea pig. Therefore, we ascertained the distribution of mu-opioid receptors in the BH with autoradiography using the mu-opioid selective agonist [H-3]DAMGO. Zn addition, we investigated the effects of estrogen on DAMGO- or the GABA(B) receptor agonist baclofen-stimulated [S-35]GTF gamma S binding in the BH. Based on the high density of mu-opioid receptors, but the lack of effects of estrogen on [S-35]GTP gamma S binding, we conclude that mu-opioid receptor interaction with its G-protein is not the target of estrogen's actions. (C) 1998 Published by Elsevier Science B.V.