PHYSIOLOGICALLY IMPORTANT ROLE FOR CENTRAL OXYTOCIN IN THE PREOVULATORY RELEASE OF LUTEINIZING-HORMONE

Recently, our laboratory has provided evidence for a physiologically relevant stimulatory influence of oxytocin (OXY) on the preovulatory luteinizing hormone (LH) surge in cycling female rats. The present study evaluated whether this stimulatory effect of OXY on LH release is exerted at a central or peripheral site of action by comparing the ability of peripheral (intravenous) or central (intracerebroventricular) administration of OXY antisera to influence the preovulatory LH surge. The peripheral injection of a very large dose of OXY antisera (0.8 ml) caused a slight attenuation of the early stages of the LH surge. In contrast, the central administration of 5 mu-l of OXY antisera completely abolished the preovulatory LH surge. The data support the hypothesis that OXY exerts a physiologically important stimulatory influence on the preovulatory LH surge which is mediated primarily at a central site of action.