脊髓RhoA/ROCK信号通路在脂多糖致大鼠炎性痛形成中的作用

Role of spinal RhoA/ROCK signaling pathway in development of lipopolysaccharide-induced inflammatory pain in rats

目的 评价脊髓RhoA/ROCK信号通路在脂多糖致大鼠炎性痛形成中的作用.方法 清洁级成年雄性SD大鼠52只,体重180 ～ 220 g,采用随机数字表法分为4组（n=13）：生理盐水组（NS组）、炎性痛组（IP组）、RhoA抑制剂C3 exoenzyme组（LC组）和ROCK抑制剂Y27632组（LY组）.采用足底注射脂多糖25 μl（300 ng）的方法制备大鼠炎性痛模型.NS组注射等容量生理盐水;LC组和LY组分别在足底注射脂多糖前30 min鞘内注射C3 exoenzyme 10 pg和Y27632 10 nmol.于足底注射脂多糖前（T0）、注射后1、3、5、12和24 h（T1-5）时测定大鼠机械痛阈和热痛阈,于T3时痛阈测定后取大鼠L45脊髓背角,采用RT-PCR法测定TNF-α和IL-1β的mRNA表达.结果 与NS组比较,IP组、LC组和LY组T2-5时机械痛阈和热痛阈降低,IP组T3时脊髓背角TNF-α和IL-1β的mR-NA表达上调（P＜0.05）;与IP组比较,LC组和LY组T2-5时机械痛阈和热痛阈升高,T3时脊髓背角TNF-α和IL-1β的mRNA表达下调（P＜0.05）.结论 脊髓RhoA/ROCK信号通路参与了脂多糖致大鼠炎性痛形成的过程.

Objective To evaluate the role of spinal RhoA/ROCK signaling pathway in the development of lipopolysaccharide （IP）-induced inflammatory pain（IP） in rats.Methods Fifty-two male Sprague-Dawley rats, weighing 180-220 g, were equally randomized into 4 groups using a random number table： normal saline group （group NS） , LPS group, RhoA inhibitor C3 exoenzyme group （group LC） , and ROCK inhibitor Y27632 group （group LY）.Inflammatory pain was induced by injecting LPS 25 μl （300 ng） into the plantar surface of hindpaws in IP, LC and LY groups, while the equal volume of normal saline was injected instead in NS group.C3 exoenzyme 10 pg and Y27632 10 nmol were injected intrathecally at 30 min prior to LPS administration in LC and LY groups, respectively.Before LPS injection （T0） , and at 1, 3, 5, 12 and 24 h after LPS injection （T1-5） , the mechanical and thermal pain thresholds were measured.Five rats in each group were sacrificed after pain thresholds were measured at T3, and L4.5 segments of the spinal cord were removed for determination of tumor necrosis factor-alpha （TNF-α） and interleukin-1 beta （IL-1β） mRNA expression in spinal dorsal horns by real-time reverse transcriptase-polymerase chain reaction.Results Compared with group NS, the mechanical and thermal pain thresholds were significantly decreased at T2-5in IP, LC and LY groups, and TNF-α and IL-1β mRNA expression was up-regulated at T3 in IP group.Compared with group IP, the mechanical and thermal pain thresholds were significantly increased at T2-5, and TNF-α and IL-1β mRNA expression was down-regulated at T3 in LC and LY groups.Conclusion Spinal RhoA/ROCK signaling pathway is involved in the development of LPS-induced IP in rats.