Many neuropeptide systems in the DRN, particularly those related to anxiety and stress (Npy, Crh, galanin, hypocretin/oxytocin – reviewed in Kormos and Gaszner (2013), were altered by binge drinking (Table 2). Npy and Crh work in opposition and must be balanced to maintain homeostasis and resistance to stress (Gilpin, 2012; Sajdyk et al., 2004; Valdez and Koob, 2004). Npy is increased but receptors Npy1r and Npy5r are decreased, perhaps as an adaptation to increased Npy. In contrast to the DRN, Npy5r was found to be increased in both the accumbens shell (Acb-sh) and central nucleus of the amygdala (CeA) of these same animals (McBride et al., 2014). Crh is anxiogenic (Valdez and Koob, 2004). P rats have lower Crh in multiple brain regions, increased Crhr1 receptors (Ehlers et al., 1992), and decreased levels of Crhr2 in several regions (Yong et al., 2014). These two receptors have different affinities for Crh, with Crhr1 binding Crh at low concentrations and Crhr2 binding only at high concentrations. Crhr1 is activated by acute stress and initiates decreased serotonin release and active coping, while Crhr2
