rats (Kemppainen et al., 2012). These data stand in contrast to other studies examining delta and kappa effects on drinking. Delta opioid agonists specific to the delta opioid receptor sub-type one administered subcutaneously reduced drinking in mice, while a non-subtype-specific delta opioid agonist had the opposite effect by increasing drinking relative to baseline (van Rijn et al., 2010). Further, the delta antagonist, naltridole, when delivered to the nucleus accumbens reduces drinking (Hyytia and Kiianmaa, 2001).
