Author(s): Wallace MN, Geddes JG, Farquhar DA, Masson MR
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Abstract This study provides the first evidence that nitric oxide is released by astrocytes surrounding beta-amyloid plaques. Nitric oxide is involved in many neuropathological conditions and can have either a neuroprotective or a neurotoxic function depending on its concentration and the redox state of the tissue. It is produced by the enzyme nitric oxide synthase, which can be located by a simple histochemical technique for demonstrating NADPH diaphorase. Using this method we examined tissue from 10 brains where there were varying numbers of beta-amyloid plaques in the cerebral cortex. In the 6 brains with moderate or high densities of plaques, primitive and cored plaques were associated with between 1 and 10 reactive astrocytes that contained NADPH diaphorase or were immunoreactive for the inducible form of nitric oxide synthase. In the 4 brains which had only low densities of plaques, the plaques were not associated with diaphorase-containing astrocytes. The percentage of plaques associated with 1 or more NADPH diaphorase-containing astrocyte varied between 1 and 21\% and was correlated with the density of plaques. Astrocytes were the only form of NADPH diaphorase-positive glial cell associated with the plaques. There was no evidence of any nitric oxide synthase occurring in microglia.
This article was published in Exp Neurol
and referenced in Journal of Alzheimers Disease & Parkinsonism