(H-3)HEMICHOLINIUM-3 BINDING-SITES IN POSTMORTEM BRAINS OF HUMAN PATIENTS WITH ALZHEIMERS-DISEASE AND MULTIINFARCT DEMENTIA

(H-3)Hemicholinium-3 ((H-3)HCh-3), a potent, selective, and competitiv e inhibitor of the high-affinity choline uptake process was used for t he detection of high-affinity choline carriers in the hippocampus (gyr us parahippocampalis), neocortex (gyrus frontalis medius), and cerebel lum (lobulus semilunaris inferior) in autopsy samples of people with A lzheimer's disease, multi-infarct dementia and from other psychiatric and nonpsychiatric patients, The effect of postmortem delay was elimin ated by means of the cerebellum used as an individual standard. The de nsity of (H-3)HCh-3 binding sites was decreased in the hippocampus and neocortex from individuals with multi-infarct dementia and unchanged in the brain tissue from people with Alzheimer's disease in comparison with control patients. No changes in dissociation constants were foun d. In Alzheimer's disease, high-affinity choline transport appears to be reduced by a dysfunction of cholinergic neuronal membrane rather th an by a significant decrease in the number of presynaptic cholinergic nerve terminals. Results provide evidence of a decrease in the number of nerve endings in people with multi-infarct dementia and suggest dif ferent vulnerability of particular brain areas to vascular disorders.