Direct effects of androgens on lateral hypothalamic neuronal activity in the male rat: I. A microiontophoretic study

Unit neuronal activity in the lateral hypothalamic-medial forebrain bundle region (LHA-MFB) of the male rat is modified following an increase of plasma testosterone level. In order to determine possible direct action of hormones on LHA-MFB neurons, unit discharge frequencies were recorded during local microiontophoresis of testosterone and estradiol, and electroosmotic application of cholesterol. Thirteen cells did not respond, 9 were nonspecifically depressed by all the steroids tested, 13 were excited by both sex-steroids, and 11 were specifically activated by testosterone. The short latencies of the responses suggest a direct effect of steroids on the plasma membrane sites.