Possible involvement of the adenosinergic system in flunarizine anticonvulsant activity in rats

The present work deals with an EEG and behavioral study on the effects of the calcium antagonist flunarizine against the convulsions due to pentylenetetrazole in rats. Flunarizine (1.5-18 mg/kg, i.p.) has a dose-dependent protective effect against pentylenetetrazole-induced seizures (50 mg/kg, i.p.). Tonic seizures were primarily affected by flunarizine. N6-L-phenylisopropyl-adenosine (an A1 adenosine receptor agonist) potentiated the anticonvulsant effects of flunarizine at the dose of 0.05 mg/kg, i.p. Conversely, caffeine (10 and 50 mg/kg, i.p.) reverted the antiepileptic activity of flunarizine in a dose-related way. These results confirm some previous reports on the anticonvulsant effects of flunarizine in various experimental models. They also suggest that some interesting interactions may exist between flunarizine and the adenosine system.