Area-Specific Differences in OH8dG and mtDNA4977 Levels in Alzheimer Disease Patients and Aged Controls

Summary: Mitochondrial DNA in the brain gets damaged at different rates across brain regions depending on type of damage, age, and Alzheimer's diseasedness.

Interestingness: 1

Paper by AMS Lezza, P Mecocci, A Cormio, M Flint Beal, A Cherubini, P Cantatore, U Senin and MN Gadaleta in the Journal of Anti-Aging Medicine, Volume 2, Issue 3, Fall 1999.

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They track two different common mutations to mitochondrial DNA (mtDNA) in post-mortem brains of 14 people, 8 with Alzheimer's, 6 control. One type of mutation is a deletion of 4977 bases in the mtDNA, which, going by the large amount of google results, seems to be quite a common thing to check for. The other is a product of oxidation, 8-hydroxy-2'-deoxyguanosine (OH8dG).

It seems like very little data to be taking the conclusions seriously, but the abstract is a good summary of the results. If nothing else, it seems that Alzheimer's disease patients have more oxidised mtDNA than non-Alzheimer's disease patients.
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Abstract follows:

The levels of mitochondrial DNA (mtDNA) 4977-bp deletion (mtDNA4977) and 8-hydroxy-2'-deoxyguanosine (OH8dG) have been measured in different brain areas of aged controls and Alzheimer disease patients. An area-specific distribution of the OH8dG level among three cortices and the cerebellum in aged controls as well as in Alzheimer disease patients has been found. It seems that in control subjects the age-related oxidative damage to mtDNA, represented by OH8dG content, shows a faster increase in the temporal and parietal cortices than in the frontal and in the cerebellum. In Alzheimer disease patients, where the OH8dG values are always higher than those of the control counterparts, such an area-specific distribution is maintained, but with a less significant difference among the cortices. The mtDNA4977 levels, on the other hand, are very different between frontal and parietal cortices on one side and temporal cortex and cerebellum on the other, both in control subjects and in Alzheimer disease patients. In general, it seems that the lowest mtDNA4977 levels coexist with the highest OH8dG contents in controls and, even more, in Alzheimer disease patients. This suggests that oxidative stress takes place both in aging and in Alzheimer disease, where it is amplified; however, mtDNA4977 level correlates with OH8dG content only in the frontal cortex of controls.