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An in situ hybridization study was done on the decreased acetyltransferase mRNA expression in the nucleus basalis of Meynert in Alzheimer disease. It was shown that the level of expression of choline acetyltransferase mRNA in the nucleus basalis of Meynert from patients with Alzheimer disease was markedly decreased. These results suggest that the expression of choline acetyltransferase mRNA may be down-regulated in the cholinergic neurons identified in the nucleus basalis of Alzheimer patients.

Caspase-3 is an effector of apoptosis in experimental models of Parkinson's disease (PD). However, its potential role in the human pathology remains to be demonstrated. Using caspase-3 immuno-histochemistry on the postmortem human brain, we observed a positive correlation between the degree of neuronal loss in dopaminergic (DA) cell groups affected in the mesencephalon of PD patients and the percentage of caspase-3-positive neurons in these cell groups in control subjects and a significant decrease of caspase-3-positive pigmented neurons in the substantia nigra pars compacta of PD patients compared with controls that also could be observed in an animal model of PD. This suggests that neurons expressing caspase-3 are more sensitive to the pathological process than those that do not express the protein. In addition, using an antibody raised against activated caspase-3, the percentage of active caspase-3-positive neurons among DA neurons was significantly higher in PD patients than in controls. Finally, electron microscopy analysis in the human brain and in vitro data suggest that caspase-3 activation precedes and is not a consequence of apoptotic cell death in PD.