Cortical NMDA receptor properties and membrane fluidity are altered in Alzheimer's disease

NMDA receptor density as measured by the specific binding of [H-3]MK 801 was significantly decreased (about 20%) in the frontal but not in the parietal cortex of postmortem brain samples of Alzheimer's disease (AD) patients (n = 21), when compared with control brains (n = 20). Membrane fluidity was not altered in the frontal cortex samples, but was slightly reduced in the parietal cortex samples of the AD patients. Since AD-specific histopathological changes (densities of senile plaques and neurofibrillary tangles) were about similar in both areas, it is concluded that the reductions of NMDA receptor densities in the frontal cortex is independent of AD-specific histopathological changes and of changes of membrane fluidity.