Altered ATP hydrolysis induced by pentylenetetrazol kindling in rat brain synaptosomes

The ectonucleotidase pathway is an important metabolic source of extracellu lar adenosine. Adenosine has potent anticonvulsant effects on various model s of epilepsy. One of these models is pentylenetetrazol (PTZ) kindling, in which repeated administration of subconvulsive doses of this drug induces p rogressive intensification of seizure activity. In this study, we examine t he effect of a single convulsive injection (60 mg/kg, i.p.) or 10 successiv e (35 mg/kg, i.p.) injections of PTZ on synaptosomal ectonucleotidases. Our results have shown that no changes in ectonucleotidase activities were see n at 0, 1, and 24 h or at 5 days after a single convulsive PTZ injection. H owever, after PTZ-kindling, rats which were more resistant to seizure devel opment presented an increase in ATP hydrolysis in synaptosomes from hippoca mpus and cerebral cortex (44% and 28%, respectively). These results suggest that changes in nucleotide hydrolysis may represent an important mechanism in the modulation of chronic epileptic activity in this model.