Abstract | OBJECTIVES: METHODS: A [(3)H] quinuclidinyl benzilate (QNB) binding assay and an immunoprecipitation assay using subtype-specific antibodies were performed. Each antibody was raised against fusion proteins containing peptides corresponding to the third intracellular (i3) loops of the respective mAChR subtype. RESULTS: The total amounts of mAChRs were significantly lower in the preparations of temporal cortices from DLBD and Alzheimer's disease than in those from dead controls (seven cases). In both diseases, the proportion of the m3 receptor in the frontal cortex was significantly increased and that of the m4 receptor in the temporal cortex was significantly decreased compared with the control specimens. The proportions of the m1 and m2 subtypes were significantly different in the temporal cortex. The proportion of the m1 receptor was significantly greater in the DLBD brains, whereas that of the m2 receptor was significantly greater in the Alzheimer's disease brains than in the controls. CONCLUSIONS: The m1 receptor is the major subtype in the cerebral cortex, and m2 is known to be present at presynaptic terminals. The higher proportions of m1 in DLBD and m2 in Alzheimer's disease suggest that the manner of degeneration in the cholinergic system is different between the diseases. It is hypothesised that a severe depletion of presynaptic cholinergic projective neurons causes the upregulation of m1 receptor in the temporal cortex in DLBD.
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Authors | K Shiozaki, E Iseki, H Uchiyama, Y Watanabe, T Haga, K Kameyama, T Ikeda, T Yamamoto, K Kosaka |
Journal | Journal of neurology, neurosurgery, and psychiatry
(J Neurol Neurosurg Psychiatry)
Vol. 67
Issue 2
Pg. 209-13
(Aug 1999)
ISSN: 0022-3050 [Print] England |
PMID | 10406992
(Publication Type: Journal Article)
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Chemical References |
- Immune Sera
- Receptors, Muscarinic
- Quinuclidinyl Benzilate
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Topics |
- Aged
- Aged, 80 and over
- Alzheimer Disease
(metabolism)
- Binding Sites
(physiology)
- Female
- Frontal Lobe
(metabolism)
- Humans
- Immune Sera
- Male
- Parkinson Disease
(metabolism)
- Precipitin Tests
- Quinuclidinyl Benzilate
(metabolism)
- Receptors, Muscarinic
(metabolism)
- Temporal Lobe
(metabolism)
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