Variation in the frequency of complex forms of mitochondrial DNA in different brain regions of senescent mice

• Published in: Brain research Vol. 300; no. 1; p. 41
• Main Authors: Bulpitt, K J, Pikó, L
• Format: Journal Article
• Language: English
• Published: Netherlands 21.05.1984
• Subjects: Aging; Animals; Brain Chemistry; Cerebellum - analysis; Cerebral Cortex - analysis; Corpus Striatum - analysis; DNA, Circular - analysis; DNA, Mitochondrial - analysis; Hippocampus - analysis; Male; Medulla Oblongata - analysis; Mesencephalon - analysis; Mice; Mice, Inbred BALB C; Microscopy, Electron
• ISSN: 0006-8993
• DOI: 10.1016/0006-8993(84)91339-8

It was shown previously that the frequency of an aberrant form of mitochondrial DNA (mtDNA), double-sized circular molecules or circular dimers, increased significantly in the brain of senescent mice, to about 2% versus less than 0.1% in the brain of adult mice. To follow up these observations, we isolated total mtDNA from 6 different brain regions of 29-month-old male BALB/c mice and examined it for the occurrence of circular dimers and other complex forms by electron microscopy. There was a statistically highly significant variability in the occurrence of circular dimer mtDNA among the 6 brain regions. The frequencies of circular dimers were: medulla, 3.3%; cortex, 1.7%; midbrain, 1.1%; cerebellum, 0.9%; hippocampus, 0.5%; and striatum, 0.2%. The frequency of catenated (topologically interlinked) molecules varied only slightly, from 4 to 6%. On the basis of the available literature, a correlation appears to exist between age-related tissue pathology of the mouse brain and the increased incidence of circular dimer mtDNA. Although no cause-effect relationships can be established, it is suggested that the frequency of circular dimer mtDNA may be a useful marker in assessing the general physiological condition of the aging brain.