Prior research has implicated the GABA system in the NAc in the mediation of ethanol self-administration. For example, Hodge, Chappelle and Samson (1995) found that both the GABAAR agonist, muscimol and the GABAAR antagonist, bicuculline, decreased operant responding for ethanol, primarily by producing an earlier termination of responding within the session. However, the site of drug infusion for this study was in the core region of the NAc, rather than the shell. Two other studies have found that infusion of the GABAAR antagonist, SR 95531, decreased ethanol self-administration when infused into the NAc shell (Hyytia & Koob 1995; Eiler & June 2007), a finding that is congruent with the present findings. However, recently, Stratford and Wirtshafter (2011) reported that infusion of muscimol into the medial shell decreased ethanol intake at doses that increase sucrose and chow intake. Hence, the manipulation used here, a down-regulation of α4 subunits, which would be predicted to reduce inhibition in some neurons within the shell, produces a similar behavioral effect as a general inhibition of GABAARs (and the neurons expressing these receptors). This difference suggests
