Involvement of 5-HT2 Receptors in the Wet-dog Shake Behaviour Induced by 5-hydroxytryptophan in the Rat

The wet-dog shake behaviour induced by 5-hydroxytryptophan (5-HTP) was used as a model of central 5-hydroxytryptamine (5-HT) receptor activity in the rat. The wet-dog shake behaviour induced by 5-HTP was dose-dependent. Selective 5-HT2 receptor antagonists ketanserin, pirenperone and methysergide (with little selectivity) were administered to rats displaying the wet-dog shake behaviour. The three antagonists produced a rapid and dose-dependent inhibition of wet-dog shakes. Pirenperone was more potent than ketanserin, which was more potent than methysergide at inhibiting wet-dog shake behaviour. Since 5-HT2 receptor antagonists inhibit the 5-HTP-induced wet-dog shakes it is proposed that the wet-dog shakes induced by 5-HTP are mediated by activation of 5-HT2 receptors.