NUCLEUS BASALIS LESIONS SUPPRESS SPIKE AND WAVE DISCHARGES IN RATS WITH SPONTANEOUS ABSENCE EPILEPSY

Cholinergic drugs were shown to affect spike and wave discharges in a selected strain of Wistar rats with generalized non-convulsive absence epilepsy, named GAERS (Genetic Absence Epilepsy Rats from Strasbourg) . The involvement of cholinergic transmission from the nucleus basalis in the control of absence seizures in GAERS was investigated in the p resent study, by examining the effects of unilateral excitotoxic lesio ns of this nucleus on the occurrence of spike-wave discharges. Ibotena te (0.01 M) and quisqualate (0.03 and 0.06 M)-induced lesions of the n ucleus basalis suppressed spike-wave discharges in the cortex ipsilate ral to the lesion. The suppression was associated with a disappearance of both acetylcholinesterase-fibres in the cerebral cortex and cholin e acetyltransferase immunopositive neurons within the nucleus basalis. Concomitantly, the background electroencephalographic activity was sl owed. These results suggest that cholinergic innervation of the cerebr al cortex by the nucleus basalis is involved in the occurrence of gene ralized non-convulsive seizures, in relation to the control of cortica l activation.