Wolfson Institute for Biomedical Research, Division of Medicine, University College London, London WC1E 6BT, United Kingdom.
William Harvey Research Institute, Barts and the London School of Medicine and Dentistry, Queen Mary University of London, London EC1M 6BQ, United Kingdom.
eNeuro. 2023 Sep 26;10(9). doi: 10.1523/ENEURO.0151-23.2023. Print 2023 Sep.
Drive from peripheral neurons is essential in almost all pain states, but pharmacological silencing of these neurons to effect analgesia has proved problematic. Reversible gene therapy using long-lived chemogenetic approaches is an appealing option. We used the genetically activated chloride channel PSAM-GlyR to examine pain pathways in mice. Using recombinant AAV9-based delivery to sensory neurons, we found a reversal of acute pain behavior and diminished neuronal activity using and GCaMP imaging on activation of PSAM-GlyR with varenicline. A significant reduction in inflammatory heat hyperalgesia and oxaliplatin-induced cold allodynia was also observed. Importantly, there was no impairment of motor coordination, but innocuous von Frey sensation was inhibited. We generated a transgenic mouse that expresses a CAG-driven FLExed PSAM-GlyR downstream of the locus that requires Cre recombinase to enable the expression of PSAM-GlyR and tdTomato. We used Na1.8 Cre to examine the role of predominantly nociceptive Na1.8+ neurons in cancer-induced bone pain (CIBP) and neuropathic pain caused by chronic constriction injury (CCI). Varenicline activation of PSAM-GlyR in Na1.8-positive neurons reversed CCI-driven mechanical, thermal, and cold sensitivity. Additionally, varenicline treatment of mice with CIBP expressing PSAM-GlyR in Na1.8+ sensory neurons reversed cancer pain as assessed by weight-bearing. Moreover, when these mice were subjected to acute pain assays, an elevation in withdrawal thresholds to noxious mechanical and thermal stimuli was detected, but innocuous mechanical sensations remained unaffected. These studies confirm the utility of PSAM-GlyR chemogenetic silencing in chronic pain states for mechanistic analysis and potential future therapeutic use.
从周围神经元驱动几乎是所有疼痛状态所必需的，但药理学沉默这些神经元以实现镇痛已被证明存在问题。使用长效化学遗传方法进行可逆基因治疗是一种有吸引力的选择。我们使用遗传激活的氯离子通道 PSAM-GlyR 来研究小鼠的疼痛通路。使用基于重组 AAV9 的递送来递送到感觉神经元，我们发现使用烟碱和 GCaMP 成像在 PSAM-GlyR 激活时，急性疼痛行为和神经元活动的逆转，以及使用烟碱和 GCaMP 成像在 PSAM-GlyR 激活时，对炎性热痛觉过敏和奥沙利铂诱导的冷感觉过敏的显著减少。重要的是，没有运动协调能力的损害，但无害的 von Frey 感觉受到抑制。我们生成了一种转基因小鼠，该小鼠在下游表达 CAG 驱动的 FLExed PSAM-GlyR ，该基因需要 Cre 重组酶才能使 PSAM-GlyR 和 tdTomato 表达。我们使用 Na1.8 Cre 来研究主要为伤害性的 Na1.8+神经元在癌症引起的骨痛（CIBP）和慢性缩窄性损伤（CCI）引起的神经性疼痛中的作用。PSAM-GlyR 在 Na1.8 阳性神经元中的烟碱激活逆转了 CCI 驱动的机械、热和冷敏感性。此外，在表达 PSAM-GlyR 的 Na1.8+感觉神经元的 CIBP 小鼠中，烟碱治疗逆转了癌症疼痛，这是通过体重支撑来评估的。此外，当这些小鼠接受急性疼痛测定时，检测到对有害机械和热刺激的退缩阈值升高，但无害机械感觉不受影响。这些研究证实了 PSAM-GlyR 化学遗传沉默在慢性疼痛状态下用于机制分析和潜在未来治疗用途的效用。
