NADPH-diaphorase histochemistry in the rat cerebral cortex and hippocampus: effect of electrolytic lesions of the nucleus basalis magnocellularis

Unilateral or bilateral electrolytic lesions of the nucleus basalis magnocellularis (NBM) increased NADPH-diaphorase in the fronto-parietal cortex and in the CA 1–CA 3 fields of the hippocampus. NBM is the cholinergic basal forebrain nucleus supplying the fronto-parietal cortex but not the hippocampus. This increase was more remarkable at 4 weeks than at 2 weeks after lesioning. Monolateral or bilateral lesioning of the NBM increased to a similar extent NADPH-diaphorase. The number of neurons expressing NADPH-diaphorase was not statistically different between sham-operated and NBM-lesioned rats. These results indicate that similarly as reported in experimental damage of several brain areas, lesions of the NBM induce NADPH-diaphorase. The induction of this marker for nitric oxide synthase occurs both in the target of projections arising from the NBM such as the frontal cortex and in an area not directly supplied by NBM such as the hippocampus. Lesion-induced NADPH-diaphorase increase may contribute to neurodegenerative changes caused by damage of the NBM area.