Evaluation of the 5-hydroxytryptamine receptor agonist 8-hydroxy-2-(di-n-propylamino)tetralin in different rodent models of epilepsy.

The effects of the serotonin (i.e. 5-hydroxytryptamine; 5-HT) S1 receptor agonist, 8-hydroxy-2-(di-n-propylamino)tetralin (8-OH-DPAT), and the 5-HT precursor L-5-hydroxytryptophan (5-HTP) were compared in different models of epilepsy. 5-HTP significantly increased the threshold for electroconvulsions and pentylenetetrazol-induced seizures in mice and rats but exerted no anticonvulsant effects in epileptic gerbils and amygdaloid-kindled rats. The anticonvulsant effect of 5-HTP against electroconvulsions in rats could be attenuated by the S2 receptor antagonist, ketanserin. 8-OH-DPAT displayed no anticonvulsant effects in the seizure models examined but gave rise to proconvulsant effects in mice. Differences between 5-HTP and 8-OH-DPAT were also observed in terms of behavioural changes in response to both drugs. The data indicate that S2 receptors may be involved in the anticonvulsant effect of 5-HTP.