Chapter 12 - Animal models of environmental manipulations causing epigenetic modifications that increase risk for major depressive disorder and anxiety disorders

Abstract

Major depressive disorder and anxiety disorders have a high lifetime prevalence in the population. Risk for these diseases is increased by genetic predisposition, environmental exposures, and gene by environment interactions which are believed to be mediated, at least in part, by epigenetic mechanisms. To better investigate epigenetic modifications, animal models of environmental challenges are employed and changes in gene expression and behavior that model aspects of these disorders are assessed. This chapter describes several such models using rodents. These models include maternal exposure to stress and toxins in the prenatal period; maternal care in the postnatal period; and exposure to social stress and hormonal changes in adulthood. Behavior and gene expression changes in response to these manipulations have been linked to changes in DNA methylation and histone acetylation of specific genes, including Bdnf, Nr3c1 (GR), and Crh in the brain. Existing treatments for anxiety and depression are not effective for many patients. Animal models like those described in this chapter could help target better drugs for the treatment of these disorders.