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Dementia of the Alzheimer's Type: Changes in Hippocampal L‐[ 3 H]Glutamate Binding
Author(s) -
Greenamyre J. Timothy,
Penney John B.,
D'Amato Constance J.,
Young Anne B.
Publication year - 1987
Publication title -
journal of neurochemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.75
H-Index - 229
eISSN - 1471-4159
pISSN - 0022-3042
DOI - 10.1111/j.1471-4159.1987.tb04127.x
Subject(s) - hippocampal formation , glutamate receptor , glutamatergic , hippocampus , neuroscience , medicine , endocrinology , excitatory postsynaptic potential , alzheimer's disease , neurotransmitter , chemistry , nmda receptor , receptor , biology , disease
Glutamate or a related excitatory amino acid is thought to be the major excitatory neurotransmitter of hippocampal afferents, intrinsic neurons, and efferents. We have used an autoradiographic technique to investigate the status of excitatory amino acid receptors in the hippocampal formation of patients dying with dementia of the Alzheimer type (DAT). We examined l‐[ 3 H]glutamate binding to sections from the hippocampal formation of six patients dying of DAT and six patients without DAT and found marked reductions in total [ 3 H]glutamate binding in all regions of hippocampus and adjacent parahippocampal cortex in DAT brains as compared to controls. When subtypes of excitatory amino acid receptors were assayed, it was found that binding to the N ‐methyl‐d‐aspartate (NMDA)‐sensitive receptor was reduced by 75–87%, with the greatest loss found in stratum moleculare and stratum pyramidale of CA1. Binding to quisqualate (QA)‐sensitive receptors was reduced by 45–69%. There were smaller reductions (21–46%) in GABA A receptors in DAT cases. Muscarinic cholinergic receptors assayed in adjacent sections of hippocampal formation were unchanged in DAT. Benzodiazepine receptors were reduced significantly only in parahippocampal cortex by 44%. These results suggest that glutamatergic neurotransmission within the hippocampal formation is likely to be severely impaired in Alzheimer's disease. Such impairment may account for some of the cognitive decline and memory deficits that characterize DAT.