Programa de Pós-Graduação em Ciências Biológicas: Fisiologia, Rua Sarmento Leite, 500, 90050-170, Instituto de Ciências Básicas da Saúde, Universidade Federal do Rio Grande do Sul, Porto Alegre, RS, Brazil.
Regular exercise improves learning and memory, including during aging process. Interestingly, the imbalance of epigenetic mechanisms has been linked to age-related cognitive deficits. However, studies about epigenetic alterations after exercise during the aging process are rare. In this preliminary study we investigated the effect of aging and exercise on DNA methyltransferases (DNMT1 and DNMT3b) and H3-K9 methylation levels in hippocampus from 3 and 20-months aged Wistar rats. The animals were submitted to two exercise protocols: single session or chronic treadmill protocol. DNMT1 and H3-K9 methylation levels were decreased in hippocampus from aged rats. The single exercise session decreased both DNMT3b and DNMT1 levels in young adult rats, without any effect in the aged group. Both exercise protocols reduced H3-K9 methylation levels in young adult rats, while the single session reversed the changes on H3-K9 methylation levels induced by aging. Together, these results suggest that an imbalance on DNMTs and H3-K9 methylation levels might be linked to the brain aging process and that the outcome to exercise seems to vary through lifespan.
"Exercise is another preventive measure that has been shown to modulate the expression of genes regulating the methylation and acetylation of DNA and protein. Studies have shown decreased expression of DNA methyltransferases  and increased expression of HAT  in the hippocampus of rats which exert their epigenetic influence by increasing the expression of neurotrophic factors in brain. Further evidence was provided by Scopel et al. by showing that exercise regime of 20 minutes for 2 weeks for wistar rat attenuates the damage in hippocampal slices submitted to ischemia in-vitro opening the field for further investigation. "
[Show abstract][Hide abstract] ABSTRACT: Neurodegenerative diseases such as Alzheimer's disease (AD), Parkinson's disease (PD), Amyotrophic lateral sclerosis (ALS) and retinal degeneration have been studied extensively and varying molecular mechanisms have been proposed for onset of such diseases. Although genetic analysis of these diseases has also been described, yet the mechanisms governing the extent of vulnerability to such diseases remains unresolved. Recent studies have, therefore, focused on the role of environmental exposure in progression of such diseases especially in the context of prenatal and postnatal life, explaining how molecular mechanisms mediate epigenetic changes leading to degenerative diseases. This review summarizes both the animal and human studies describing various environmental stimuli to which an individual or an animal is exposed during in-utero and postnatal period and mechanisms that promote neurodegeneration. The SNPs mediating gene environment interaction are also described. Further, preventive and therapeutic strategies are suggested for effective intervention.
[Show abstract][Hide abstract] ABSTRACT: Significant progress has been made in understanding the neurobiological mechanisms through which exercise protects and restores the brain. In this feature review, we integrate animal and human research, examining physical activity effects across multiple levels of description (neurons up to inter-regional pathways). We evaluate the influence of exercise on hippocampal structure and function, addressing common themes such as spatial memory and pattern separation, brain structure and plasticity, neurotrophic factors, and vasculature. Areas of research focused more within species, such as hippocampal neurogenesis in rodents, also provide crucial insight into the protective role of physical activity. Overall, converging evidence suggests exercise benefits brain function and cognition across the mammalian lifespan, which may translate into reduced risk for Alzheimer's disease (AD) in humans.
[Show abstract][Hide abstract] ABSTRACT: It has been described that histone acetylation levels are decreased in several cellular and in vivo neurodegeneration models as well as in normal brain aging, although the impact of the aging process on histone deacetylases (HDAC) activity yet remains poorly understood. Therefore, our aim was to evaluate the effect of the aging process on HDAC activity in hippocampi and frontal cortices from 3 and 18-months-old Wistar rats. The animals were decapitated at different times of day, in the early morning and in afternoon. HDAC activity was increased in hippocampus from the aged group. Besides, the hippocampal HDAC activity was also significantly increased in early morning. A significant interaction between age and time of the day was observed in frontal cortices, given that the HDAC activity was higher in early morning in the aged group. These data support the hypothesis that the aging-related dysfunction may be related, at least in part, to acetylation imbalance through HDAC activity in rat brain.
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