Inhibitory action of a calcium channel blocker (nimodipine) on seizures and brain damage induced by pilocarpine and lithium-pilocarpine in rats.

The present work studied the effect of a calcium channel blocker (nimodipine) on rat behavioural changes and brain lesions observed after seizures induced by high doses of pilocarpine (400 mg/kg, s.c.; P400), and the association of lithium (3 mEq/kg, i.p., daily during 7 days) plus pilocarpine (a single dose of 15 mg/kg, s.c.) administered 24 h after the last injection of lithium. In the P400 model, nimodipine (5 or 10 mg/kg, i.p.) inhibited convulsions, status epilepticus, and significantly decreased the percentage of death and cerebral changes (Mann-Whitney, P = 0.0057). In the lithium-pilocarpine (Li-Pi) induced seizures, nimodipine even increased convulsive action and did not interfere with brain lesions. The results suggested that a calcium channel mechanism is involved in the P400 induced seizures, and that there is a difference in the physiopathology of epileptic seizures and brain damage induced by either P400 and Li-Pi models.