2009), highlighting the need to confirm the link between early life TGX-221 chemical structure stress and epigenetic alterations at this locus. Early life stress has been shown to bring about epigenetic changes at the arginine vasopressin gene (Avp), with a regulatory region in the gene being hypomethylated following MS

(Murgatroyd et al. 2009). Similar changes following an environmental stressor have been observed in several other Inhibitors,research,lifescience,medical genes including Bdnf (Fuchikami et al. 2009; Roth et al. 2009), Crh (Elliott et al. 2010), Dlgap2 (Chertkow-Deutsher et al. 2010), Mecp2, Cnr1, and Crhr2 (Franklin et al. 2010), suggesting that such changes may occur in multiple neurobiological pathways in response to stress. In this study, our aim was to explore physiological, behavioral, and epigenetic changes in response to early life stress in the mouse, and determine whether these differed as a function of genetic background. We used MS, a validated model of early postnatal life stress in rodents, that is known to induce long lasting effects on emotional Inhibitors,research,lifescience,medical behavior and stress-reactivity (Boccia and Pedersen Inhibitors,research,lifescience,medical 2001; Holmes et al. 2005), changes to the hypothalamic–pituitary–adrenocortical (HPA) axis (Schmidt et al. 2004), and result in a significant loss of neurons in the hippocampus of adult mice (Fabricius

et al. 2008). MS models vary in the literature both in the frequency and in the length of separation, which has led to a disparity in phenotypic changes seen. We chose to use the single 24 h separation model to avoid the phenotypic variability found in repeated separation models, as the length of the separation period seems to mediate whether a positive or negative behavioral change is seen (Holmes et al. 2005), possibly Inhibitors,research,lifescience,medical due

to the increase of maternal care after Inhibitors,research,lifescience,medical the separation (Millstein and Holmes 2007). Corticosterone levels in response to a stress challenge and a range of behavioral phenotypes were measured in adult mice following MS. DNA methylation levels in the promoter regions of three candidate genes in two strains of inbred mouse (C57BL/6J and DBA/2J) following MS were determined; based on previous studies we chose Nr3c1 and Calpain Avp as likely targets of early life stress, and Nr4a1, encoding a brain-expressed nuclear hormone receptor, was selected given its involvement in disorders such as schizophrenia and depression. Methods Animals C57BL/6J and DBA/2J mice were bred in the Biological Services Unit at the Institute of Psychiatry, Kings College London using original stocks [respective stock numbers: 000664, 000671] purchased from The Jackson Laboratory (Bar Harbor, ME). DBA/2J and C57BL/6J strains were selected as these represent members of a priority list based on the most well-characterized, commonly used strains for gene manipulation and crosses (Mouse Phenome Project, http://aretha.jax.org/pub-cgi/phenome/mpdcgi?rtn=docs/home).