"In both brain regions, we have been able to directly relate these chromatin changes to some of the behavioral abnormalities observed," Nestler said.
In animal models of chronic stress, he and his colleagues were able to manipulate these two brain areas in ways that produced antidepressant-like effects.
In other research, a team at the University of Massachusetts Medical School in Worcester are examining changes in methylation, a type of chemical modification of the DNA and of histones, the protein "backbone" of chromatin.
"We found that these chemical modifications in brain chromatin are dynamically regulated from the perinatal period to old age and could be involved in epigenetic control of gene expression, including genes for brain-derived neurotrophic factor and others implicated in mood and anxiety spectrum disorders," Dr. Schahram Akbarian said in a prepared statement.
He said the findings could help in the design of new antidepressant treatments. Preliminary findings from research in mice suggest that chemical modification of epigenetic-related factors could enhance response to widely used antidepressants.
Researchers at McGill University in Montreal found that separating rats from their mothers at an early age altered the methylation state of specific genes in the hippocampus, resulting in long-term behavioral changes.
They found that differences in a mother's care, such as licking and grooming, can change the development of rat pups' hormonal and behavioral response to stress, resulting in lifelong changes in the pups' response to stress and how they process information about stressors.
"This may reveal experience-dependent adaptability in the chemistry of the DNA and chromatin structure," researcher Michael Meaney said in a prepared statement.
More information
The U.S. National Institute of Mental Health has more about depression.
