Brief Communication Role of medial prefrontal cortex Narp in the extinction

Narp knockout (KO) mice demonstrate an impaired extinction of morphine conditioned place preference (CPP). Because the medial prefrontal cortex (mPFC) has been implicated in extinction learning, we tested whether Narp cells in this region play a role in the extinction of morphine CPP. We found that intracranial injections of adenoassociated virus (AAV) ex-pressing wild-type (WT) Narp into the mPFC of Narp KO mice rescued the extinction and the injection of AAV expressing a dominant negative form of Narp (NarpN) into the mPFC of WT mice impaired the extinction of morphine CPP. These findings suggest that Narp in the mPFC mediates the extinction of morphine CPP. [Supplemental material is available for this article.] Neuronal activity-regulated pentraxin (Narp) is an immediate ear-ly gene product that is induced by neuronal activity and is secret-ed at synapses where it binds to the extracellular surface of AMPA receptors (AMPARs; O’Brien et al. 1999). Narp-positive neurons are present in many limbic and cortical regions, including the me-dial prefrontal cortex (mPFC), hippocampus, hypothalamus, and amygdala (Tsui et al. 1996; Reti et al. 2002a,b; Reti and Baraban 2003; Johnson et al. 2010). Narp has been implicated in regulatin