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. 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.

G蛋白信号调控因子2（Regulator of G protein signaling-2, RGS9-2）是一种纹状体蛋白，在阿片类、单胺类及其他G蛋白偶联受体（G protein-coupled receptor, GPCR）的信号响应过程中发挥关键调控作用。本研究采用小鼠神经性疼痛 spared神经损伤模型，探究伏隔核（nucleus accumbens, NAc）内的RGS9-2调控三环类抗抑郁药（tricyclic antidepressants, TCAs）作用的分子机制——伏隔核是参与情绪奖赏与动机调控的脑区。在伏隔核中阻断RGS9-2的功能，可增强三环类抗抑郁药地昔帕明的药效，并显著加速其起效时间。RGS9-2通过调控G蛋白α与βγ亚基对效应分子的激活，影响多种蛋白质相互作用、磷蛋白水平，以及组蛋白去乙酰化酶5（histone deacetylase 5, HDAC5，一种表观遗传修饰因子）的功能，而这些过程均与三环类抗抑郁药的响应密切相关。此外，RNA测序（RNA-seq）分析结果显示，伏隔核内的RGS9-2可调控众多已知参与痛觉感受、镇痛及抗抑郁药物作用的基因表达。本研究为阐明神经性疼痛状态下三环类抗抑郁药作用的伏隔核特异性细胞机制提供了全新见解。本次RNA测序研究旨在揭示神经性疼痛与抗抑郁药物处理条件下，RGS9-2对伏隔核内基因表达调控的影响。本研究共纳入18份样本，涵盖6个实验组，每组均设置3次生物学重复。