in reduced Pomc expression in the hypothalamus, while increased expression of Dnmt1 was observed in the pituitary (Todkar et al., 2015). Within the paraventricular nucleus (PVN), adult animals subjected to maternal separation showed hypomethylation and increased expression of arginine vasopressin (Avp) (Murgatroyd et al., 2009), a gene that has been implicated in the pathology of anxiety and depression (Neumann and Landgraf, 2012). Behaviorally, these animals showed a hyperactive stress response and altered passive stress coping (Murgatroyd et al., 2009). Another group exposed mice to a 24 hour maternal separation on postnatal day nine and found altered methylation of Avp and Nr3c1 within the hippocampus of adult animals. These changes in DNA methylation were paralleled by changes in anxiety-like behavior and an increased corticosterone response to stress (Kember et al., 2012). Together, these studies demonstrate the capacity for stress during the early postnatal period to elicit long-term effects on DNA methylation that may mediate altered stress responsivity across the lifespan.
