The aging brain: less neurons could be better.
ABSTRACT Molecular and cellular markers of age-related alterations in the brain vary significantly between different brain regions and between different types of neurons. In contrast to what had been thought for years, it has recently become clear that only specific types of neurons show an age-related loss of cells. Based on previous work we hypothesize that there is an interrelationship between two important processes in the aging brain: some types of neurons in the aging brain show an accumulation of unrepaired nuclear (n) nDNA damage since no cells are lost during aging. In contrast, other types of neurons show no accumulation of unrepaired nDNA damage since the cells with the greatest decline in nDNA repair capacity and the highest amount of nDNA damage are lost during aging. Most interestingly, the former types of neurons seem to correlate strongly with those types of neurons afflicted in age-related cognitive decline and in the selective neuronal vulnerability in Alzheimer's disease. Therefore, modulation of the nDNA damage response by stimulation of nDNA repair processes, or by elimination of neurons with a high amount of unrepaired nDNA damage in the aging brain, may lead to a functional improvement in networks of these types of neurons and to a better functioning of the aging brain in general. Ultimately, the implication of this strategy may lead to the prevention of AD.
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ABSTRACT: Ageing of the brain leads to impairments in cognitive and motor skills, and is the major risk factor for several common neurological disorders such as Alzheimer disease (AD) and Parkinson disease (PD). Recent studies suggest that normal brain ageing is associated with subtle morphological and functional alterations in specific neuronal circuits, as opposed to large-scale neuronal loss. In fact, ageing of the central nervous system in diverse mammalian species shares many features, such as atrophy of pyramidal neurons, synaptic atrophy, decrease of striatal dopamine receptors, accumulation of fluorescent pigments, cytoskeletal abnormalities, and reactive astrocytes and microglia. To provide the first global analysis of brain ageing at the molecular level, we used oligonucleotide arrays representing 6,347 genes to determine the gene-expression profile of the ageing neocortex and cerebellum in mice. Ageing resulted in a gene-expression profile indicative of an inflammatory response, oxidative stress and reduced neurotrophic support in both brain regions. At the transcriptional level, brain ageing in mice displays parallels with human neurodegenerative disorders. Caloric restriction, which retards the ageing process in mammals, selectively attenuated the age-associated induction of genes encoding inflammatory and stress responses.Nature Genetics 08/2000; 25(3):294-7. · 35.21 Impact Factor
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ABSTRACT: The early notion that cancer is caused by mutations in genes critical for the control of cell growth implied that genome stability is important for preventing oncogenesis. During the past decade, knowledge about the mechanisms by which genes erode and the molecular machinery designed to counteract this time-dependent genetic degeneration has increased markedly. At the same time, it has become apparent that inherited or acquired deficiencies in genome maintenance systems contribute significantly to the onset of cancer. This review summarizes the main DNA caretaking systems and their impact on genome stability and carcinogenesis.Nature 06/2001; 411(6835):366-74. · 38.60 Impact Factor
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ABSTRACT: Beta-amyloid peptide is the main constituent of senile plaques and is implicated in the pathogenesis of Alzheimer's disease. It has been shown to be both neurotoxic and neurotrophic in vivo, and its effects have been suggested to be mediated in part by alterations in membrane transport. In the present study, we investigated the effect of beta-amyloid (1-40) on choline transport in cultured PC12 cells. We found that exposure to 46 or 92 microM beta-amyloid (1-40) increased [14C]choline flux in PC12 cells in a concentration-dependent manner, whereas exposure to reverse sequence beta-amyloid (40-1) had no effect. If there is a similar effect in vivo, the increased beta-amyloid dependent permeability to choline could lead to depletion of cellular choline stores and could contribute to the selective vulnerability of cholinergic neurons in Alzheimer's disease.Neuroscience Letters 10/1997; 234(1):71-3. · 2.03 Impact Factor