Nicotinic binding sites in cerebral cortex and hippocampus in alzheimer's dementia

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Abstract
Postmortem cerebral neocortical and hippocampal samples were taken from patients who died with dementia of the Alzheimer type (DAT) and individuals without diagnoses of neurological or psychiatric disease (control). Nicotinic binding was assayed with 20 nM [3H]acetylcholine ([3H]ACh) in the presence of atropine, or with 4 nM (-)-[3H]Nic). Binding of both ligands was lower in the following regions from DAT vs. control brains (P≤0.05): superior, middle and inferior temproal gyri, orbital frontal gyrus, middle frontal gyrus, pre- and postcentral gyri, inferior parietal lobule, and hippocampal endplate. Values of the correlation coefficient (r's) for binding of the nicotinic cholinergic ligands in these regions ranged from 0.70 to 0.93 (P's0.05). Here too, correlations between binding of the two ligands were statistically significant in control and DAT groups (r's=0.92,P's0.05). The findings support a loss of neocortical and hippocampal nicotininc cholinergic binding sites in DAT. Further study is necessary to better characterize the regional losses of nicotinic binding in DAT and to resolve the differences in binding measured by [3H]ACh and (-)-[3H]Nic in the H1-subiculum and H2 (field of Rose) regions.