Study on the anticonvulsant activity of clonidine against pentylenetetrazol-induced seizures in rats: pharmacological evidence of alpha 2-adrenoceptors mediation.

: The present work deals with an EEG and behavioral study of the interaction of alpha-adrenoceptor antagonists on the anticonvulsant activity of clonidine against the convulsions due to pentylenetetrazol (PTZ) in rats. Clonidine's ability (0.5 mg/kg, i.p.) to inhibit the tonic seizures and mortality induced by PTZ (75 mg/kg, i.p.) was counteracted by pretreatment with yohimbine and mianserine (10 mg/kg, i.p.). On the contrary, prazosin (10 mg/kg, i.p.) did not influence the anticonvulsant effect of clonidine. The results suggest that central alpha 2-adrenoceptors play an important role in the control of motor and EEG convulsions elicited by PTZ.