The effects of chronic treatment with a calcium channel antagonist on two types of generalized epilepsies in rats.
Although calcium antagonists possess antiepileptic properties in various models of epilepsy, their role after chronic administration and in models for generalized absence epilepsy has not been studied. Twenty-four male Wistar rats, aged 84-94 weeks, were chronically provided with EEG electrodes. Two groups received dietary nimodipine (860 ppm) for 14 and 21 weeks, respectively, while a control group received the same rat chow without nimodipine. The EEG was recorded for 3 h to establish the effects of nimodipine on spike-wave discharges. Next, 50 mg/kg pentylenetetrazol (PTZ) was injected to establish the effects on convulsive epilepsy, and the EEG was recorded for 30 min. All animals had spontaneous spike-wave discharges (SWD), but there were no differences between the three groups. However, chronic nimodipine treatment had a significant effect on PTZ-induced seizures: the group that had been treated with nimodipine for 21 weeks showed significantly more and longer-lasting seizures than the control group. The facilitating effects of chronically administered of nimodipine on PTZ-induced seizures are striking and opposite to those reported in the literature. In a second study, nimodipine was administered acutely, but no effects of nimodipine on PTZ-induced epilepsy could be detected. It can be concluded that chronic dietary administration of a calcium antagonist induces different effects on PTZ-induced seizures than acute administration in aged Wistar rats with spontaneous occurring SWD.
van Luijtelaar
E L
EL
Department of Psychology, University of Nijmegen, The Netherlands.
Ates
N
N
van der Staay
F J
FJ
D000818:Animals; D002121:Calcium Channel Blockers / Q000494:pharmacology*; D004032:Diet; D004569:Electroencephalography / Q000187:drug effects; D004832:Epilepsy, Absence / Q000503:physiopathology; D004829:Epilepsy, Generalized / Q000139:chemically induced / Q000235:genetics / Q000503:physiopathology*; D004830:Epilepsy, Tonic-Clonic / Q000503:physiopathology; D008297:Male; D009553:Nimodipine / Q000494:pharmacology*; D010433:Pentylenetetrazole; D051381:Rats; D017208:Rats, Wistar
D002121:Calcium Channel Blockers; D009553:Nimodipine; D010433:Pentylenetetrazole