A new paper in Proceedings of the National Academy of Sciences (PNAS) by Suderman et al. reports on the discovery of the ability of early life experiences to influence DNA methylation patterns in the hippocampal region of the brain. The researchers examined the methylation patterns of the hippocampus in humans who have been victimised by abuse. There was also a control group of non-abused persons. The results were then compared with rats who, as infants, had been subject to different maternal care.
The paper’s abstract reports,
Early life experience is associated with long-term effects on behavior and epigenetic programming of the NR3C1 (GLUCOCORTICOID RECEPTOR) gene in the hippocampus of both rats and humans. However, it is unlikely that such effects completely capture the evolutionarily conserved epigenetic mechanisms of early adaptation to environment. Here we present DNA methylation profiles spanning 6.5 million base pairs centered at the NR3C1 gene in the hippocampus of humans who experienced abuse as children and nonabused controls. We compare these profiles to corresponding DNA methylation profiles in rats that received differential levels of maternal care. The profiles of both species reveal hundreds of DNA methylation differences associated with early life experience distributed across the entire region in nonrandom patterns. For instance, methylation differences tend to cluster by genomic location, forming clusters covering as many as 1 million bases. Even more surprisingly, these differences seem to specifically target regulatory regions such as gene promoters, particularly those of the protocadherin α, β, and γ gene families. Beyond these high-level similarities, more detailed analyses reveal methylation differences likely stemming from the significant biological and environmental differences between species. These results provide support for an analogous cross-species epigenetic regulatory response at the level of the genomic region to early life experience. [emphasis added]
If this is correct, environmental conditions may have the ability to affect epigenetic chemical marking of DNA. Indeed, as this medicalxpress press release on the study put it, the study “confirms a biological process that embeds social experience in DNA in the brain and that affects not just a few genes but entire networks of genes.”