Autoradiographic localization of muscarinic cholinergic receptors in the hippocampus of patients with senile dementia.

Muscarinic cholinergic receptors were localized by autoradiography in the hippocampi from 4 patients with senile dementia (S. D.) and 4 neurologically normal age-matched controls. A large number of senile plaques were observed in the hippocampi from S.D. patients, whereas they were not observed in control brains. The distribution and density of muscarinic receptors was similar in control and S.D. patients. In the hippocampus, areas rich in receptors were subiculum, strata oriens, pyramidalis and radiatum and the molecular layer of the dentate gyrus. The density of autoradiographic grains over the senile plaques was comparable to that over the surrounding neuropil, indicating that senile plaques have muscarinic receptors.