Prelimbic to Accumbens Core Pathway Is Recruited in a Dopamine-Dependent Manner to Drive Cued Reinstatement of Cocaine Seeking

Glutamate inputs to nucleus accumbens (NAc) facilitate conditioned drug-seeking behavior and primarily originate from medial prefrontal cortex (mPFC), basolateral amygdala (BLA), and ventral subiculum of the hippocampus (vSub). These regions express Fos (a marker of neural activity) during cue-induced reinstatement of cocaine seeking, but only subpopulations of neurons within these regions drive drug seeking. One way to identify and functionally distinguish neural subpopulations activated during drug-seeking is to examine their projection targets. In rats, we examined Fos expression during cue-induced reinstatement of cocaine-and sucrose-seeking in prelimbic cortex (PL), infralimbic cortex (IL), BLA, and vSub neurons that project to NAc core (NAcC) or NAc shell (NAcSh). Neurons in PL, BLA, and vSub that project to NAcC, but not NAcSh, expressed Fos during cue-induced cocaine seeking, but not sucrose seeking. However, only activation of the PL-NAcC pathway positively correlated with cocaine reinstatement behavior, unlike BLA or vSub inputs to NAcC. To confirm a functional role for the PL-NAcC pathway, and to test the hypothesis that this pathway is recruited in a dopamine-dependent manner, we used a pharmacological disconnection approach whereby dopamine signaling was blocked in PL and glutamate signaling was blocked in the contralateral NAcC. This disconnection attenuated cue-induced reinstatement of cocaine seeking but had no effect on reinstatement of sucrose seeking. Our results highlight a role for the PL-NAcC pathway in cocaine seeking and show that these glutamatergic projections are recruited in a dopamine-dependent manner to drive reinstatement.