Increased biosynthesis of Alzheimer amyloid precursor protein in the cerebral cortex of rats with lesions of the nucleus basalis of Meynert

The nucleus basalis of Meynert was lesioned by infusion of N-methyl-d-aspartate (NMDA) unilaterally in adult rat brain. Seven days post lesion we observed that polysomes isolated from the cerebral cortex affected by the lesion synthesized 2.6-fold greater amounts of the Alzheimer amyloid precursor protein (AAPP) compared to the nonlesioned side of the same rat brain. This increase exhibited specificity to AAPP in that overall protein synthesis was not altered by the lesion. The increase of AAPP did not alter the ratio of AAPP isotypes in rat brain (in which AAPP 695, which is lacking the protease inhibitor insert remains the predominant form). The increased synthesis did not result in the apparent accumulation of mature AAPP. These results indicate that a cholinergic lesion which models many of the neurochemical changes observed in Alzheimer's disease induces the expression of AAPP in a major projection region, the cerebral cortex.