电针干预痛转化效应及其对背根神经节中蛋白激酶C_ε表达的影响

Effect of Electroacupuncture on Pain Transition and Content of Protein Kinase C_ε in Dorsal Root Ganglia in Hyperalgesia Rats

目的:观察电针对痛觉敏化诱发大鼠机械缩足反射阈值(MWT)及腰椎背根神经节(DRG)中蛋白激酶C_ε(PKC_ε)表达的影响,探讨电针干预痛转化效应的机制。方法:第1部分:SD大鼠随机分为空白组、假敏化组、敏化组,每组6只。于大鼠左后足足底皮下注射1%角叉菜胶100μL,7d后于该足足背注射100ng/25μL前列腺素E 2(PGE 2)建立痛转化模型。分别测量大鼠造模前,第1次注射后4、24、48、72h和7d,及第2次注射后1、4、24、48h患侧足趾MWT。第2部分:SD大鼠随机分为假敏化组、敏化组、电针组、假电针组,每组6只。造模方法同第1部分。电针组于第1次注射后开始电针双侧"足三里""昆仑"穴,每次30min,1次/d,共10d。检测MWT时间点同第1部分。Western blot法检测第2次注射后48h患侧DRG中PKC_ε蛋白表达。结果:与假敏化组相比,敏化组角叉菜胶注射后4、24、48h,PGE 2注射后4、24、48h患侧足底MWT显著降低(P<0.01);与敏化组相比,电针可以显著提升角叉菜胶注射后24、48、72h及PGE2注射后24、48h患侧足底MWT(P<0.05,P<0.01),而假电针无此作用(P>0.05)。与假敏化组相比,敏化组腰椎DRG中PKC_ε表达增多(P<0.01);与敏化组相比,电针组腰椎DRG中PKC_ε表达减少(P<0.01),而假电针组无明显变化(P>0.05)。结论:电针具有良好的镇痛作用并可干预痛转化效应,其机制可能与下调患侧腰椎DRG中PKC_ε表达有关。

Objective To observe the effect of electroacupuncture（EA）on mechanical pain transition and content of protein kinase C epsilon（PKC_ε）in dorsal root ganglia（DRG）in inflammatory articular pain rats,so as to explore its peripheral mechanism underlying relieving transition from acute to chronic pain.Methods 1）In the first part of the present study,male SD rats were equally randomized into blank control,sham hyperalgesic priming（HP）,and real HP groups（n=6 in each）.The HP model was established by subcutaneous injection of 1%carrageenan（100μL）into the left hind paw（the first injection）,followed by injection of PGE 2（100 ng/25μL,the second injection）into the dorsum pedis of the same hind paw 7 days after the first injection.The mechanical withdrawal threshold（MWT）of the ipsilateral paw was detected before and 4,24,48,72 h,and 7 dafter the first injection,and 1,4,24 and 48 hafter the second injection.2）In the second part,SD rats were randomly divided into sham-HP,real HP,sham-EA and EA groups（n=6 in each）.The sham-HP and HP models were made in the same way as those in the first part.Bilateral＂Zusanli＂（ST 36）and ＂Kunlun＂（BL 60）were punctured with filiform needles and also stimulated with electrical current：2 Hz/100 Hz,0.5-1.5 mA（0.5 mA increase per 10 min）for 30 min,1 time/d from the 1 st carrageenan injection on till the end of the experiments.PKC_εprotein expression in the L 4-L 6 DRGs was assayed by Western blot 48 hafter the second injection.Results 1）In the first part of the study,compared with the sham-HP group,the MWT at 4,24、48 hafter carrageenan injection and 4,24 and 48 h after PGE 2 injection were significantly decreased in the HP model group（P〈0.01）.2）In the second part,compared with the HP group,the MWT at 24、48 and 72 hafter carrageenan injection,and 24 and 48 hafter PGE 2 injection were significantly up-regulated in the EA group（P〈0.05,P〈0.01）.3）The relative content of PKC_εin the DRGs（L 4-L 6）was significantly higher in the HP group than in the sham-HP group（P〈0.01）,but considerably lower in the EA group than in the HP group（P〈0.01）. Conclusion EA has a good effect on pain conversion in inflammatory joint pain rats,which may be related to its effect in down-regulating the PKC_εlevel in the ipsilateral lumbar DRGs.