EFFECTS OF NIMODIPINE ON L-GLUTAMATE-INDUCED SEIZURES AND CA2+ INFLUX IN HIPPOCAMPUS IN FREELY MOVING RATS

Seizure (EEG) was studied in rats unilaterally injected in the dorsal hippocampus with l-glutamate (Glu). Extracellular Ca2+ content [(Ca2+)e] in the injected area was assessed by brain microdialysis coupled to automatic atomic absorption spectrophotometry. In this experimental epileptic model, an inhibition of Glu-stimulated epileptic activity and a fall in (Ca2+)e by nimodipine (Nim, 100-mu-g.kg-1) were seen. The spike- and wave-burst frequency was reduced from 30 to 5 bursts.min-1 (P < 0.01, n = 8). Nim 25 and 50-mu-g.kg-1, without anticonvulsant activity, did not prevent the drop in (Ca2+)e. These results indicate that Nim exerts an antiepileptic effect on Glu-induced epilepsy. The mechanisms may be involved in blocking Ca2+ influx into neurons.