Epigenetic Regulation of the Hippocampus, with Special Reference to Radiation Exposure

Abstract

The hippocampus is crucial in learning, memory and emotion processing, and is involved in the development of different neurological and neuropsychological disorders. Several epigenetic factors, including DNA methylation, histone modifications and non-coding RNAs, have been shown to regulate the development and function of the hippocampus, and the alteration of epigenetic regulation may play important roles in the development of neurocognitive and neurodegenerative diseases. This review summarizes the epigenetic modifications of various cell types and processes within the hippocampus and their resulting effects on cognition, memory and overall hippocampal function. In addition, the effects of exposure to radiation that may induce a myriad of epigenetic changes in the hippocampus are reviewed. By assessing and evaluating the current literature, we hope to prompt a more thorough understanding of the molecular mechanisms that underlie radiation-induced epigenetic changes, an area which can be further explored.

Associations of screen-based sedentary activities with all cause dementia, Alzheimer’s disease, vascular dementia: a longitudinal study based on 462,524 participants from the UK Biobank

“…The association of TV viewing time exposure with higher AD risk can be explained as follows: first, TV viewing time is correlated with a higher risk of cardiovascular and cardiometabolic diseases [ 39 ], both of which are risk factors for AD [ 40 ]; second, watching TV increases time of sitting, resulting in reduced muscle activity and energy expenditure [ 41 , 42 ], further leading to physical activity reduction and cognitive decline [ 43 , 44 ]; third, TV viewing usually implies a long period of sitting after dinner in the evening, which may be harmful to cardiometabolic health [ 42 ], thereby impacting brain health [ 45 ]; forth, more TV viewing can cause passive intense sensory stimulation of the audience, and affect their emotions, so it may lead to spiritual and psychological influence [ 46 ]. In addition to its memory functions, hippocampus has been found to function in emotional coding [ 47 ]. In our study, we also found that TV viewing ≥ 4 h/day and 2–3 h/day were correlated with less hippocampus volume.…”

Acute, Low-Dose Neutron Exposures Adversely Impact Central Nervous System Function

“…Alterations in voltagegated ion channels expression, such as occurs after similar doses of charged particle radiation [24,79], could underlie the elevated neuronal responses. Radiation exposures can alter ion channel expression though direct interactions [80], generation of reactive oxygen species [6,24], alteration of epigenetic regulation [81] or due to homeostatic plasticity mechanisms that work to counteract changes in synaptic inputs [46][47][48]. Although the other intrinsic properties we surveyed following acute neutron irradiation appeared to be largely unchanged, regulation of neuronal excitability is highly multifaceted and neurons are capable of maintaining similar outward properties despite numerous changes in underlying molecular mechanisms [50].…”

Analysis of miRNA and mRNA transcription profiles changes in the hippocampus of fluorosis rats

“…miRNAs play an important role in the regulation of learning and memory functions in the hippocampus (Kusuda et al 2011). The hippocampus is an area of the brain closely related to learning and memory functions, and miRNAs are small molecule RNAs that can regulate gene expression, affecting the functional properties of neurons related to learning and memory functions by inhibiting or promoting the expression of speci c genes (Saw and Tang 2020). miR-132 and miR-212 play an important role in learning and memory functions in the hippocampus (Julia et al 2015).…”