青藤碱对神经病理性痛大鼠脊髓背角P2X3R mRNA及COX-2 mRNA表达的影响

Effects of sinomenine on expression of P2X3 receptor mRNA and cyclooxygenase-2 mRNA in spinal dorsal horns of rats with neuropathic pain

目的 评价青藤碱对神经病理性痛大鼠脊髓背角P2X3受体（P2X3R） mRNA及环氧化酶-2（COX-2） mRNA表达的影响.方法 健康成年雄性Wistar大鼠54只,6～8周龄,体重180～220 g,采用随机数字表法,将其分为3组（n=18）：假手术组（S组）、神经病理性痛组（NP组）和青藤碱组（SIN组）.采用慢性坐骨神经压迫损伤法建立神经病理性痛模型.SIN组于术毕即刻腹腔注射盐酸青藤碱注射液40 mg/kg,S组和NP组注射等容量生理盐水,1次/d,连续注射14 d.于术前1d、术后3、7和14 d时测定机械缩足反应阈（MWT）和热缩足反应潜伏期（TWL）,测定痛阈后处死,取L4-6节段脊髓,采用RT-PCR法检测脊髓背角P2X3R mRNA及COX-2 mRNA的表达.结果 与S组比较,NP组和SIN组MWT降低,TWL缩短,脊髓背角P2X3R mRNA及COX-2 mRNA表达上调（P＜0.05）;与NP组比较,SIN组MWT升高,TWL延长,脊髓背角P2X3R mRNA及COX-2 mRNA表达下调（P＜0.05）.结论 青藤碱减轻大鼠神经病理性痛的机制可能与抑制脊髓背角P2X3R mRNA及COX-2 mRNA表达有关.

Objective To evaluate the effects of sinomenine on the expression of P2X3 receptor （P2X3R） mRNA and cyclooxygenase-2 （COX-2） mRNA in the spinal dorsal horns of rats with neuropathic pain （NP）.Methods Fifty-four male Wistar rats,aged 6-8 weeks,weighing 180-220 g,were randomly assigned into 3 groups （n =18 each） using a random number table：sham operation group （group S）,group NP and sinomenine （group SIN）.The animals were anesthetized with 10% chloral hydrate 350 mg/kg.NP was induced by chronic constrictive injury.In group SIN,sinomenine 40 mg/kg was intraperitoneally injected immediately after the end of operation once a day for 14 consecutive days,while the equal volume of normal saline was given in the same way in S and NP groups.The mechanical paw withdrawal threshold to yon Frey stimuli （MWT） and paw withdrawal latency to thermal nociceptive stimulus （TWL） were measured at 1 day before operation and 3,7 and 14 days after operation.The rats were sacrificed after measurement of pain threshold,and their lumbar segments （L4-6） of the spinal cord were immediately removed for determination of P2X3 R and COX-2 mRNA expression in the spinal cord （by real-time fluorescent quantitative PCR）.Results Compared with group S,the MWT was significantly deceased,the TWL was shortened and the expression of P2X3R and COX-2 mRNA was up-regulated in NP and SIN groups.Compared with group NP,MWT and TWL were significantly increased,the TWL was prolonged and the expression of P2X3R and COX-2 mRNA was down-regulated in group SIN.Conclusion Sinomenine can mitigate NP in rats possibly through inhibiting the expression of P2X3R mRNA and COX-2 mRNA in the spinal dorsal horns.