& Naassila, 2013). Opioid signaling pathways in the amygdala have also been identified as an epigenetic target of ethanol. Alcohol dependence has been shown to be associated with abnormal regulation of the Dynorphin/κ-opioid system with increased consumption linked to activation of this system contributing to the negative affective state. This may play a role in the motivational aspects of dependence and drug seeking and compulsive behaviors (Walker & Koob, 2008). Epigenetic regulation of the prodynorphin gene promoter following ethanol administration showed an increase in H3K9 acetylation (activating) and a decrease in H3K27 tri-methylation (repressive) marks in the amygdala of rats (D’Addario et al., 2013).
