LESIONS OF THE CHOLINERGIC NUCLEI IN THE RAT BASAL FOREBRAIN - EXCITOTOXINS VS AN IMMUNOTOXIN

Infusion of the excitotoxins, ibotenic acid, quisqualic acid, or AMPA, into the medial septal nucleus, diagonal band, and the nucleus basali s magnocellularis of rats produced less cholinergic cell loss as asses sed by choline acetyltransferase activity in the projection fields, co rtex and hippocampus, than that obtainable by intraventricular adminis tration of the immunotoxin, 192 IgG-saporin. All excitotoxins produced reductions in tissue levels of some monoamines, while no decreases we re found for the immunotoxin. All toxins produced acquisitional impair ment in the hidden platform water maze. This behavioral deficit was sl ightly greater for the excitotoxic-lesioned rats than for those given 192 IgG-saporin at a dose which produced ChAT depletions similar to th e most potent excitotoxin (AMPA). This supports the idea that some of the behavioral effects produced by excitotoxic lesions are due to the cholinergic basal forebrain lesion and some are due to noncholinergic damage.