电针足三里穴对烫伤后脓毒症大鼠肝损伤的影响

Effect of electro-acupunctare at Zusanli on liver injury in a rat model of sepsis after scald

目的 评价电针足三里穴对烫伤后脓毒症大鼠肝损伤的影响.方法 SPF级健康雄性SD大鼠50只,体重200 ～ 250 g,2～3月龄,采用随机数字表法,将其分为5组（n=10）：对照组（C组）、烫伤后脓毒症组（SS组）、电针组（E组）、非经非穴组（NE组）和含α7烟碱型乙酰胆碱受体特异性拮抗剂α-银环蛇毒素组（α-BGT组）.采用背部20％总体表面积Ⅲ度烫伤后即刻静脉注射胞壁酰二肽5mg/kg的方法构建大鼠烫伤后脓毒症模型.E组于静脉注射胞壁酰二肽即刻给予双侧足三里穴电针刺激（电压3V,波宽2 ms,频率3 Hz）持续刺激12 min,间隔8h刺激1次,持续2 d;NE组于静脉注射胞壁酰二肽即刻在双侧足三里穴旁5 mm处给予电针刺激,方法同E组;α-BGT组股静脉注射α-BGT1.0 mg/kg（用生理盐水稀释至1 ml）,再行电针刺激,方法同E组.持续刺激48 h后,取肝组织行病理学观察.抽取腹主动脉血样检测血清谷丙转氨酶（ALT）和谷草转氨酶（AST）的水平;ELISA法检测肿瘤坏死因子（TNF-α）和高迁移率族蛋白1（HMGB1）的水平;RT-PCR法检测肝组织NOD样受体2（NLR2）mRNA的表达,Western blot法检测受体相互作用蛋白-2（RIP2）的表达.结果 与C组比较,SS组血清ALT、AST、TNF-α和HMGB1水平升高,肝组织NLR2 mRNA和RIP2蛋白表达上调（P＜0.05）;与SS组比较,E组血清ALT、AST、TNF-α和HMGB1水平降低,肝组织NLR2 mRNA和RIP2蛋白表达下调（P＜0.05）,NE组上述指标差异无统计学意义（P＞0.05）.与E组比较,α-BGT组血清ALT、AST、TNF-α和HMGB1浓度升高,肝组织NLR2 mRNA和RIP2蛋白表达上调（P＜0.05）.SS组、NE组和α-BGT组肝组织病理损伤明显,EA组病理损伤程度减轻.结论 电针足三里穴可减轻烫伤后脓毒症大鼠肝损伤,其机制可能与抑制肝组织NLR2/RIP2信号转导通路,激活α7烟碱型乙酰胆碱受体介导的胆碱能抗炎通路有关.

Objective To evaluate the effect of electro-acupunctare at Zusanli on liver injury in a rat model of sepsis after scald.Methods Fifty SPF male Sprague-Dawley rats,weighing 200-250 g,aged 2-3 months,were randomly divided into 5 groups （n =10 each） using a random number table：control group （group C）; sepsis after scald group （group SS）; electro-acupuncture at Zusanli group （group E）; electric stimulation of non-acupoint group （group NE）; electro-acupuncture at Zusanli ＋ α-bungarotoxin （α-BGT） group （group α-BGT）.The rats were subjected to a third degree scald covering 20% of the total body surface area （TBSA） and sepsis was induced with muramyl dipeptide （MDP） 5 mg/kg injected into the femoral vein immediately after scald.Electro-stimulation （3 V,2 ms,3 Hz） of bilateral Zusanli acupoints or non-acupoints was performed for 12 min every 8 h for 2 consecutive days starting from the time point immediately after MDP was injected in group E.In group NE,electro-stimulation was performed at the points 5 mm lateral to the acupoints of bilateral Zusanli and the method was similar to those previously described in group E.In group α-BGT,α-BGT 1.0 μg/kg （in normal saline 1 ml） was injected into the femoral vein before electric stimulation,then electro-stimulation was performed and the method was similar to those previously described in group E.After 48 h of continuous stimulation,liver specimens were obtained for microscopic examination of the pathological changes.The blood samples were obtained from the abdominal aorta for determination of the levels of serum ALT and AST,tumor necrosis factor-alpha （TNF-α）,and high mobility group box-1 （HMGB1） （by ELISA）,and expression of Nod-like receptor 2 （NLR2） mRNA （by RTPCR） and receptor-interacting protein 2 （RIP2） in the liver tissues （by Western blot）.Results The serum ALT and AST,TNF-α and HMGB-1 levels and NLR2 mRNA and RIP2 expression in liver tissues were significantly higher in SS group than in C group.Compared with SS group,the serum ALT,AST,TNF-α and HMGB1 levels were significantly decreased and NLR2 mRNA and RIP2 expression was down-regulated in E group,and no significant changes were found in the parameters mentioned above in NE group.Compared with E group,the serum ALT,AST,TNF-α and HMGB1 levels were significantly increased,and NLR2 mRNA and RIP2 expression was up-regulated in α-BGT group.The pathological changes in liver tissues were significantly reduced in group EA as compared with SS,NE and α-BGT groups.Conclusion Electro-acupuncture at Zusanli can reduce liver injury in a rat model of sepsis after scald and inhibition of NLR2/RIP2 signaling pathway and activation of cholinergic antiinflammatory pathway mediated by α7 nicotinic acetylcholine receptors in liver tissues may be involved in the mechanism.