Failure to antagonize the 8-hydroxy-2-di-n-propylamino)tetralin-induced facilitation of male rat sexual behavior by the administration of 5-HT receptor antagonists.

The administration of the putative 5-hydroxytryptamine (5-HT) agonist, 8-hydroxy-2-(di-n-propylamino)tetralin (8-OH-DPAT) and 5-hydroxytryptophan (5-HTP) produced a facilitation and an inhibition of male rat sexual behavior, respectively. The 5-HTP-induced inhibitory effects were at least partially antagonized by the administration of metergoline, methiothepine or pirenperone. However, none of these agents were able to counteract any facilitatory effects produced by 8-OH-DPAT. It is concluded that 8-OH-DPAT does not facilitate the expression of masculine sexual behavior in the rat by stimulation of 5-HT1 or 5-HT2 receptors.