The potential therapeutic utility of OXT will invariably depend on its effectiveness following its systemic administration. This raises the question as to whether peripheral administration of the neuropeptide effectively penetrates the blood-brain barrier to influence brain function (Lee et al., 2018). Historically, peripherally administered OXT was not thought to pass through the blood-brain barrier in quantities sufficient to alter behavior (Opacka-Juffry and Mohiyeddini, 2012) but rather, impact behavior via a feed-forward mechanism that involves stimulated release of endogenous OXT (Rossoni et al., 2008, Ludwig et al., 2002, Ermisch et al., 1985). However, a number of studies have recapitulated effects of systemic OXT administration with direct (icv. or site-specific) intracranial infusions across a number of behavioral tasks (Cox et al., 2017, Lee et al., 2018, Slattery and Neumann, 2010, Windle et al., 1997, Love, 2014, Ring et al., 2006). Additionally, peripheral administration of OXT has been shown to induce Fos expression in OXT neurons in the PVN (Carson et al., 2010b, Leong et al., 2017), suggesting that peripheral administration may induce endogenous central release. In a recent study, Smith et al.,
