The effects of L type calcium channels on the electroencephalogram recordings in WAG/RIJ rat model of absence epilepsy

Abstract

BACKGROUND: Epilepsy is one of the most important central nervous system disorder and 1% of the total world population suffers from this disorder which require a chronic drug treatment. Most of the researchers suggested that excessive calcium entry into neurons is the main triggering event in the initiation of epileptic discharges but the role of L type calcium channels has not been clarified in absence epilepsy. AIM: In this study, it is aimed to investigate the antiepileptic effects of nifedipine, an L type calcium channel blocker and BAY K8644, an L type calcium channel opener in a genetic model of absence epilepsy in WAG/Rij rats. MATERIALS AND METHODS: Thirty two WAG/Rij rats were allocated into four groups; sham (only saline injected), only nifedipine (an L type calcium channel blocker) injected group (40 mu g/2 mu l; 60 mu g/2 mu l; 80 mu g/2 mu l), only BAY K8644 (1,4 Dihydro-2,6-dimethyl-5-nitro-4-trifluoromethyl- phenyl-3-pyridine carboxylic acid methyl ester) (L-type Ca2+-channel activator) injected group (40 mu g/2 mu l; 60 mu g/2 mu l; 80 mu g/2 mu l) and combination of their most effective doses BAY K8644 (60 mu g/2 mu l) after nifedipine (60 mu g/2 mu l) injected group. All agents were given by intracerebroventricular injection. The beta, alpha, theta and delta wave ratios of electroencephalogram recordings and the frequency and duration of SWDs (spike and wave discharges) were analyzed and compared between four groups. RESULTS: Nifedipine increased the number and duration of spike wave discharges whereas BAY K8644 decreased both of them. When BAY K8644 was given after nifedipine, there was no significant difference with control group. CONCLUSIONS: L type calcium channels play an activator role on spike wave discharges and have positive effects on the duration and frequency.