Effects of centrally injected amylin on sexual behavior of male rats

Amylin (AMY) is a peptide of pancreatic origin principally involved in the carbohydrate metabolism, but that may interfere with central and peripheral dopamine (DA) pathways. The peptide, injected intracerebroventricularly (I CV) at the dose of 2.5 mu g/rat, induced a decrease of copulatory activity in good copulators (GCO) and sluggish (SLU) male rats. The dose of 0.1 mu g /rat did not affect significantly the sexual behavior of GCO rats, whereas AMY 0.5 mu g/rat increased only the latency and reduced the frequency of ej aculation. At the dose of 2.5 mu g/rat AMY antagonized the activation of se xual behavior induced by the DA receptor agonist, apomorphine administered subcutaneously (SC) at the dose of 100 mu g/kg. Moreover, this inhibitory e ffect was blocked hy the calcitonin gene-related peptide and AMY receptor a ntagonist, CGRP (8-37) fragment (injected ICV at the dose of 1 mu g/rat). T hese data suggest that AMY may exert inhibitory effects on male sexual beha vior in rats, probably interfering with central DA neurotransmission and wi th CGRP receptors. (C) 1999 Elsevier Science Inc. All rights reserved.