Neuronal activity-regulated pentraxin expressed in medial prefrontal cortex neurons is not necessary for extinction of heroin self-administration

The medial prefrontal cortex (mPFC) plays a key role in extinction learning. Previously, we found that expression of a neuronal activity-regulated pentraxin (Narp) dominant-negative construct in the mPFC of mice blocked extinction of morphine-conditioned place preference. To further investigate the role of mPFC Narp in the extinction of drug seeking, we tested whether mPFC Narp is necessary for the extinction of heroin self-administration in rats. Specifically, we injected an adeno-associated viral vector expressing a dominant-negative form of Narp (NarpN) into the infralimbic region of the mPFC of rats and compared lever presses during extinction to those of rats injected with a control virus. In contrast to our previous study, we found that injection of NarpN did not affect extinction of heroin self-administration. Our findings suggest that mPFC Narp is necessary for extinction of opiate seeking in the Pavlovian-conditioned place preference paradigm but not in the operant paradigm of drug self-administration.