The role of melanocortin receptors in sexual behavior in female rats

Earlier data have indicated that a-MSH may play a role for sexual behavior in rats. In this study we investigated the effects of MSH peptides on sexua l receptivity in Qvariectomized-adrenalectomized female rats, pretreated wi th benzoate of estradiol, in presence of vigorous male rats. The results sh ow that alpha -MSH significantly increases lordosis behavior in female rats after injections into the ventromedial nucleus. Interestingly, we have for the first time shown that gamma -MSH also causes significant increase in l ordosis in female rats. Furthermore, we show that HS014, an antagonist for the central MC receptors, in dose dependent manner blocks the effect of alp ha -MSH on lordosis. The results indicate that the effects of MSH peptides on female sexual behaviour are mediated through a specific MC receptor, whi ch could be the MC3 receptor. (C) 2000 Harcourt Publishers Ltd.