Researchers from Rockefeller University (USA) have found that single exposure of rats to a 30 minutes stressful episode caused widespread methylation (an epigenetic phenomenon) in the hippocampus, a brain area known to be involved in several mental disorders like depression.and schizophrenia. Repeated exposition to the same stressful episode day after day did not cause further methylation, suggesting that the animals adapt. Fluoxetine (Prozac) was only somewhat efficient in removing this epigenetic mark.
Lead researcher Richard Hunter said:
There was a thought that the genome project would reveal all in neuropsychiatric disease, but that has proven not to be the case. Epigenetics has become much more interesting because it allows us to look at how gene expression is changed by environmental events, explainable in part by histone modifications.
Source: Science Daily.
Research paper: Richard G. Hunter et al., Regulation of hippocampal H3 histone methylation by acute and chronic stress. PNAS 2009.