Accumulating evidence suggests a clear role for the oxytocinergic system in the acute reinforcing effects of drugs and alcohol (Lee et al., 2016, Lee and Weerts, 2016, Leong et al., 2018). With respect to self-administration behavior in preclinical models, administration of exogenous OXT has been shown to effectively decrease both acquisition and maintenance of alcohol (Bowen et al., 2011, MacFadyen et al., 2016, Peters et al., 2013, Peters et al., 2017, Stevenson et al., 2017a), heroin (Ibragimov et al., 1987, Kovacs et al., 1985), cocaine (Leong et al., 2017, Leong et al., 2016, Sarnyai and Kovacs, 1994, Zhou et al., 2014), methamphetamine (Carson et al., 2010a, Carson et al., 2010b, Qi et al., 2009), and nicotine (Lee et al., 2017a, Manbeck et al., 2014). However, the specific effect of OXT on drug-taking behavior appears to be dose-, drug-, use history-, and possibly species-dependent. For example, early studies showed that peripherally administered OXT slightly increased heroin self-administration in rats (Ree and Wied, 1977). In support of this finding, central OXT administration did not prevent the acquisition of morphine-conditioned place preference (CPP),
