GABAergic neurons in the insular cortex play an important role in cue-morphine reward memory reconsolidation

Abstract

Aims: There have been recent reports that reconsolidation-based interventions attenuate drug reward memories in rodents. The insular cortex (IC) is an essential part of neural circuits that underlie cue-drug memory reconsolidation. GABAergic interneurons in the IC are a potent control on network excitability and play an important role in the inhibitory mediation of reward circuits. However, the function of GABAergic neurons in the IC for memory reconsolidation remains unclear; therefore, we conducted this study to clarify this.

Main methods: We applied morphine-induced conditioned place preference (mCPP) paradigm and pharmacogenetic techniques to study the mediation effect of GABAergic neurons in the IC on mCPP reconsolidation. Moreover, we preliminarily explored the possible mechanisms of mediating GABAergic neurons in the IC involved in mCPP reconsolidation by assessing Arc and Erg-1 protein levels in the IC.

Key findings: We found that post-retrieval immediate activation of GABAergic neurons in the IC impaired mCPP reconsolidation. In addition, this effect was not reversed by a priming morphine injection. Further, post-retrieval inhibition and non-retrieval excitation of GABAergic neurons in the IC had no effect on mCPP.

Significance: Taken together, our findings suggest that GABAergic neurons in the IC are closely involved in mCPP reconsolidation. Specifically, their excitation could eliminate established mCPP and prevent the relapse risk by disruption of the reconsolidation. The underlying molecular biological mechanisms could involve reduced Arc and Erg-1 levels.

Keywords: Conditioned place preference; GABAergic neurons; Insular cortex; Morphine addiction; Pharmacogenetics; Reconsolidation.