RGS9-2-controlled adaptations in the striatum determine the onset of action and eficacy of antidepressants in neuropathic pain states

The striatal protein Regulator of G protein signaling-2 (RGS9-2) plays a key modulatory role in opioid, monoamine and other GPCR responses. Here, we use the murine spared-nerve injury model of neuropathic pain to investigate the mechanism by which RGS9-2 in the nucleus accumbens (NAc), a brain region involved in mood reward and motivation, modulates the actions of tricyclic antidepressants (TCAs). Prevention of RGS9-2 action in the NAc increases the efficacy of the TCA desipramine and dramatically accelerates its onset of action. By controlling the activation of effector molecules by G protein a and bg subunits, RGS9-2 affects several protein interactions, phosphoprotein levels, and the function of the epigenetic modifier histone deacetylase 5 (HDAC5), that are important for TCA responsiveness. Furthermore, information from RNA-seq analysis reveals that RGS9-2 in the NAc affects the expression of many genes known to be involved in nociception, analgesia and antidepressant drug actions. Our findings provide novel information on NAc-specific cellular mechanisms that mediate the actions of TCAs in neuropathic pain states. Overall design: The RNAseq study was designed in order to reveal the impact of RGS9-2 on gene regulation in the Nucleus Accumbens under neuropathic pain and antidepressant treatment conditions. A total of 18 samples was used, coprising 6 different groups , and each group consisted of three different biological replicates.

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Mitsi V, Terzi D, Purushothaman I, Manouras L, Gaspari S, Neve RL, Stratinaki M, Feng J, Shen L, Zachariou V