Pharmacological studies also support a role for NPY in the regulation of alcohol consumption, although there is some contradictory evidence regarding the role of Y1 and Y2 receptor subtypes. For example, systemic (ip.) and central (icv.) administration of a Y1R antagonist reduced alcohol intake in C57BL/6J mice (Sparta et al., 2004). In contrast, another study showed that central injection (icv.) of a Y1R agonist reduced binge-like alcohol intake in mice in a dose-related manner (Sparrow et al., 2012). Further, a Y1R antagonist (icv.) increased alcohol consumption (Sparrow et al., 2012), supporting an earlier report indicating that Y1R knockout mice exhibited increased alcohol intake (Thiele et al., 2002). A Y2 antagonist given directly into brain (icv.) reduced ethanol intake in rats (Thorsell et al., 2002), and sensitivity to this effect was greater is dependent rats (Rimondini et al., 2005). A similar finding was reported in mice (Sparrow et al., 2012), corroborating results from a study showing reduced ethanol intake in Y2R knockout mice (Thiele et al., 2002). However, in another study systemic (sc.) or central (icv.) administration of a brain-penetrant Y2
