Stressful events result in epigenetic modifications within immediate-early genes in hippocampus neurons. The findings showed that stress results in DNA demethylation in immediate-early genes thereby freeing the suppressed expression of these genes in the hippocampus and facilitating manifestation of adaptive behavioural responses.
The gene and behavioural responses to stress depended on the concentration of the compound SAM (s-adenosyl methionine). SAM is a so-called methyl donor, which is required by the enzyme that methylates DNA. When SAM levels were elevated, a subsequent stressful event did not result in DNA de-methylation but elicited enhanced DNA methylation of immediate early genes, which suppressed their expression and led to impaired behavioural adaptation.
Hans Reul, Professor of Neuroscience of Bristol’s School of Clinical Sciences, said: “We discovered in our studies a link between SAM, a compound produced by the liver, and stress-related responses in the brain, which is important to pursue in future research.
“Stress-related psychiatric disorders like major depression, anxiety and post-traumatic stress disorders are presently among the most debilitating illnesses known to man. Prevention of the detrimental effects of stress is thought to depend on effective coping and long-lasting adaptive behavioural responses.”
According to the scientists, this new research could lead to the development of novel pharmacological and other therapeutic interventions that promote appropriate behavioural responses to stress and help in the treatment of stress-evoked psychiatric disorders. http://www.bristol.ac.uk/news/2016/april/brain-adapts-to-stress.html
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