背根神经节P2X3R和TRPV1介导CFA致炎性痛大鼠不同时期痛行为的差异性研究*[1]

Study on the Differences of Pain Behavior in Rats with Inflammatory Pain in Different Periods Mediated by P2X3R and TRPV1 in Dorsal Root Ganglion

摘要:

目的：动态检测CFA诱导的炎性痛大鼠健患侧足跖厚度、痛行为和DRG中P2X3R、TRPV1受体蛋白表达，探索炎性痛不同时期痛行为差异及其可能机制。方法：采用大鼠左侧足跖注射完全弗氏佐剂建立炎性痛模型。将大鼠随机分为对照组（Con）和炎性痛组（CFA），CFA大鼠分别于造模后1、14、28和42天分批处死取材，Con大鼠仅于造模后42天处死取材。分别检测基线和造模后1、3、7、14、28、42天时大鼠双侧足跖厚度、热缩足潜伏期（PWTL）和机械缩足阈值（PWMT）；Western bolt检测健患侧L4-6 DRG中P2X3R、TRPV1蛋白表达。结果：CFA大鼠患侧足跖厚度于造模各时点均显著高于Con-Ipsi组和CFA-Contra组。CFA大鼠患侧PWTL仅于造模后1、3、7、14天时显著低于同期Con-Ipsi组，于造模后所有时点均显著低于CFA-Contra组；CFA大鼠健侧PWTL各时点与Con-Contra相比均无差异。CFA大鼠患侧PWMT于造模后所有时点均显著低于同期Con-Ipsi组，于造模后1、3、7、14、28天时显著低于同期CFA-Contra组；与同期Con-Ipsi和Con-Contra组比，CFA大鼠健侧PWMT于造模后28、42天时出现明显降低。CFA大鼠患侧DRG中P2X3R、TRPV1蛋白表达于造模后1、14、28、42天时均显著高于Con-Ipsi和Con-Contra组；CFA大鼠健侧DRG中P2X3R蛋白表达于造模后28、42天时显著多于Con-Contra组，而健侧DRG中TRPV1蛋白表达无差异。结论：CFA致炎性痛大鼠患侧足跖热痛觉过敏和机械痛觉异常持续存在，炎性痛后期可诱发出健侧足跖机械痛觉异常； P2X3R和TRPV1参与CFA大鼠早期和晚期外周痛敏化发生和维持，健侧背根神经节内P2X3R表达增加可能参与机械镜像痛的产生。

Abstract:

Objective: To explore the differences in pain behavior at diverse phases of inflammatory pain and its underlying mechanism by detecting the dynamic changes in ipsilateral and contralateral paw thickness and pain behavior as well as P2X3 and TRPV1 receptor protein expression in the dorsal root ganglion of CFA-induced inflammatory pain rats. Methods: Inflammatory pain model was established by injecting 0.1 mL of CFA into the plantar surface of rat’s left hindpaw. Rats were randomly divided into control group (Con) and CFA-induced inflammatory pain group (CFA ). CFA rats were separately sacrificed for sample collection at 1, 14, 28 and 42 day after modeling and Con rats at 42d. The changes of ipsilateral and contralateral paw thickness, paw withdraw thermal latency (PWTL) and paw withdrawal mechanical thresholds (PWMT) of rats were detected at baseline, 1d, 3d, 7d, 14d, 28d and 42d after modeling; protein expression of P2X3R and TRPV1 in ipsilateral and contralateral L4-6 DRG were detected by Western blot assay. Results: Compared with the Con-Ipsi group and CFA-Contra group at the same timepoint, the paw thickness in ipsilateral side of CFA rats significantly increased at all timepoints. Ipsilateral PWTL of CFA rats were significantly lower than those of Con-Ipsi rats at 1d, 3d, 7d and 14d after modeling and lower than those of CFA-contra rats at all timepoints observed. No significant difference in contralateral PWTL between the CFA-Contra group and the Con-Contra Group. Ipsilateral PWMT of CFA rats was remarkedly lower than those of the Con-Ipsi rats at all timepoint observed and lower than those of CFA-contra rats at 1d, 3d, 7d, 14d and 28d after modeling. Compared with the Con-Ipsi and Con-Contra group at the same timepoint, contralateral PWMT significantly decreased. Both P2X3R and TRPV1 protein expression in ipsilateral DRGs of CFA rats were higher than those of the Con-Ipsi and Con-Contra group at all timepoints. P2X3R protein expression in contralateral DRGs of CFA rats were significantly higher than those in Con-Contra group at 28d and 42d post-modeling, but TRPV1 protein remained unchanged. Conclusion: Thermal hyperalgesia and mechanical allodynia existed persistently in ipsilateral inflamed paw of rats, Contralateral uninflamed paw demonstrated mechanical allodynia at the late phase of CFA-induced inflammatory pain. P2X3R and TRPV1 contributed to the occurrence and maintenance of peripheral sensitization in the early and late phases of CFA rats, P2X3R in the contralateral DRGs might be involved in the evolution of mirror-image mechanical pain.