AMPA Receptor in Ventromedial Prefrontal Cortex Plays Different Roles in the Recent and Remote Retrieval of Morphine-Associated Memory.

Previous studies demonstrate that drug addiction can share the neural circuits in the brain with normal learning and memory. Re-exposure to drug-associated contexts, one way to retrieve the drug-associated memory, can trigger strong psychic craving and even relapse in addicts after prolonged abstinence. The ventromedial prefrontal cortex (vmPFC) has been shown to be involved in time-dependent reinstatement of drug self-administration. This work is designed to investigate the role of AMPA receptor (AMPAR) in the vmPFC in the recent and remote retrieval of morphine-associated memory. Rats were re-exposed to the morphine-paired context 1 day (recent) and 3 weeks (remote) after morphine conditioned place preference (CPP) training. Results showed that membrane expression of GluA1 and GluA2 in the vmPFC was decreased following the recent retrieval, while the membrane expression of GluA1 and GluA2 in the vmPFC was increased following the remote retrieval of morphine-associated memory. Furthermore, the microinfusion of Tat-GluA2-3Y, a GluA2 endocytosis inhibitor, into the vmPFC impaired the recent retrieval of morphine-associated memory. The microinfusion of AMPAR antagonist NBQX into the vmPFC prevented the remote retrieval of morphine-associated memory. Taking together, the present study proved that AMPAR in the vmPFC played different roles in the recent and remote retrieval of morphine-associated memory.