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Effect of nimodipine and nicardipine on EEG activity and EEG power spectra in kainic acid- induced seizures in rats

Kainic acid (KA) is an excitatory glutaminergic agonist that given intrahippocampally induces seizures. The EEG changes show spike activity originating in limbic system associated with the increase in EEG power spectra. The aim of our study was to investigate whether nimodipine and nicardipine could prevent KA-induced changes in EEG activity. Experiments were performed on adult Wistar rats. They were anesthetized and placed in a stereotaxic apparatus. Vehicle, nimodipine or nicardipine (1, 3, 10 and 30 mg/kg) had been given 30 minutes prior to intrahippocampal injection or KA (15 nmol). In each rat four screw electrodes were placed over the frontal and parietal cortex. The EEG was recorded in basal conditions and 5, 10, 15, 30 and 60 minutes after KA administration. In order to obtain EEG samples for frequency analysis. the output of EEG machine was amplified and was transmitted to an IBM AT-compatible microcomputer via analog-to-digital converter. The system was calibrated using 500 V. In order to obtain power spectra between 0-30 Hz, two 7.5 s samples of artefact free EEG were analysed. Spectral averages were computed using Fast Fourier Transform. Individual power of each frequency bin was normalised to average total power of baseline. EEG frequencies were collapsed in 1 Hz bins. Our results demonstrate that nicardipine was not effective while nimodipine in doses of 10 and 30 mg/kg prevented KA-induced excitatory changes in EEG and EEG power spectra.

nimodipine; nicardipine; kainic acid; EEG; power spectra; rat

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