Epigenetic Basis of Suicide Risk?
30 April 2008: Not all multigenerational effects are transmitted through the germ line. Elegant studies in rats demonstrate that generation-to-generation attainment of the nurturing behaviors of pup licking and grooming and arch-back nursing are not germline inherited. Rather, they are passed on to the offspring directly from the mother during the first week of postnatal life through the induction of DNA methylation and histone alterations in the hippocampus (Weaver et al. 2004). Moreover, the inherent plasticity of the epigenome allows for the reversal of these modifications in adulthood by exposure to epigenetic therapeutic agents (Weaver et al. 2006).
Is there any evidence of epigenetic programming after birth affecting human behavior? Yes, Moshe Szyf and his colleagues have now published in Plos One (McGowan et al. 2008) that the protein synthesis machinery in the suicide brain is aberrantly regulated in the hippocampus of the brain because of a promoter-wide increase in the DNA methylation of rRNA genes. The suicide subjects in this study had a history of early childhood neglect/abuse, whereas, the control victims died accidentally and had no history of abuse or neglect. Similar results have recently been found for the neuron-specific glucocorticoid receptor (NR3C1) in the hippocampus of sucide victims with a history of childhood abuse (McGowan et al. 2009). These findings are consistent with the intriguing possibility that early life events can alter the epigenetic status of genes that control neural functions, thereby contributing to individual differences in suicide risk.