Degeneration of cholinergic neurons in the basal nucleus following kainic or N-methyl-D-aspartic acid application to the cerebral cortex in the rat.

The effect on cholinergic neurons in the basal nucleus of exposing the cortex to excitotoxic amino acids was examined in the rat. Kainic or N-methyl-D-aspartic acid were applied extradurally over the cerebral cortex of one side. This resulted in a severe depletion in the numbers of neurons in the underlying cortex. The immunohistochemically identified cholinergic neurons of the ipsilateral basal nucleus showed a significant shrinkage, -31% of their mean cell area, which was comparable with the retrograde degeneration seen following direct mechanical damage of the cortex. These findings suggest that cholinergic neurons of the basal nucleus can undergo transneuronal retrograde degeneration.