Objective: To observe the effect of electroacupuncture（EA） on the expression of cytosolic phospholipase A2 （cPLA2） and apoptosis of nerve cells in rats with spinal cord injury （SCI）, so as to explore its mechanisms underlying improvement of SCI.
Methods: Seventy-two female SD rats were randomly divided into model, EA, antagonist and EA+antagonist groups, with 18 rats in each group and other 18 rats were used as the sham operation （sham） group. The SCI model was established by referring to modified Allen's method with a weight impactor. The hindlimb motor function was assessed by using Basso-Beattie-Bresnahan （BBB） score. Rats of the EA group were subjected to EA stimulation at "Dazhui"（GV14）, "Yaoyangguan"（GV3）, bilateral "Ciliao"（BL32） and "Zusanli"（ST36） for 20 min, once a day for 14 days. Rats of the antagonist group received intravenous injection followed by intraperitoneal injection of arachidonyl trifluoromethyl ketone （AACOCF3, antagonist of cPLA2）, once every other day. Rats of the EA+antagonist group received EA treatment combined with antagonist injection. After the treatment, the rats were sacrificed and the spinal cord tissue was collected for detecting the protein expression of cPLA2, p-cPLA2, Bcl-2, Bax and Caspase-3 by Western blot, and the mRNA expression of cPLA2, Bcl-2, Bax and Caspase-3 using qRT-PCR. The morphological changes of the spinal cord were detected by Nissl staining.
Results: In comparison with the sham group, the BBB score, expression of Bcl-2 protein and mRNA were significantly down-regulated （P<0.01）, whereas the expression levels of Bax, Caspase-3 and p-cPLA2 proteins and mRNAs were considerably up-regulated in the model group （P<0.01）. Compared with the model group, the BBB score, expression levels of Bcl-2 protein and mRNA were significantly up-regulated （P<0.01, P<0.05）, while the expression levels of Bax, Caspase-3 and p-cPLA2 proteins in the EA, antagonist and EA+antagonist groups, Bax and cPLA2 mRNAs in both antagonist and EA+antagonist groups, and Caspase-3 mRNA in the EA+antagonist group were obviously down-regulated （P<0.01, P<0.05）. The effect of EA+antagonist was significantly superior to EA in increasing BBB score and in lowering expression of Bax and cPLA2 mRNAs （P<0.01, P<0.05）. Nissl staining showed reduced number of nerve cells and Nissl bodies, and striped dark blue cells in the model group, which was milder in the EA and antagonist groups, particularly in the EA+antagonist group.
Conclusion: EA may improve the limb motor function of SCI rats, which may be related to its functions in down-regulating the expression of p-cPLA2, Bax and Caspase-3 and up-regulating Bcl-2 to reduce the apoptosis of nerve cells in the regional spinal cord.
目的：观察电针对脊髓损伤（SCI）大鼠胞质型磷脂酶A2 （cPLA2）的表达和神经细胞凋亡的影响，探讨电针治疗SCI的部分机制。方法：SD大鼠随机分为假手术组、模型组、电针组、阻断剂组和电针+阻断剂组，每组18只。采用改良Allen重物打击法制备SCI模型。电针组取“大椎”“腰阳关”及双侧“次髎”“足三里”进行电针治疗，每次20 min，每日1次，共14次；阻断剂组予以花生甙三氟甲基酮隔日1次腹腔注射。治疗结束对各组大鼠进行BBB评分；Western blot法检测各组大鼠脊髓组织cPLA2、磷酸化（p）-cPLA2、B淋巴细胞瘤-2（Bcl-2）、Bcl-2相关X蛋白（Bax）、半胱氨酸天冬氨酸蛋白酶3（Caspase-3）蛋白的表达；荧光定量PCR法检测各组大鼠脊髓组织cPLA2、Bcl-2、Bax、Caspase-3 mRNA的表达；尼氏染色观察脊髓组织形态变化。结果：与假手术组比较，模型组大鼠BBB评分明显降低（P<0.01），脊髓组织形态明显受损；与模型组比较，各治疗组大鼠BBB评分升高（P<0.01），脊髓组织形态都有所改善；电针+阻断剂组BBB评分高于电针组、阻断剂组（P<0.01，P<0.05），且脊髓组织形态改善优于电针组、阻断剂组。与假手术组比较，模型组大鼠脊髓组织Bcl-2蛋白及mRNA表达水平降低（P<0.01），Bax、Caspase-3蛋白及 mRNA表达水平升高（P<0.01）；与模型组比较，各治疗组大鼠脊髓组织Bcl-2蛋白及 mRNA表达水平升高（P<0.05，P<0.01），治疗各组Bax、Caspase-3蛋白表达水平降低（P<0.01，P<0.05），阻断剂组、电针+阻断剂组大鼠脊髓组织Bax mRNA表达降低（P<0.05，P<0.01），电针+阻断剂组Caspase-3 mRNA表达水平降低（P<0.05）；电针+阻断剂组Bax mRNA表达水平明显低于电针组（P<0.05）。与假手术组比较，模型组大鼠脊髓组织p-cPLA2蛋白及cPLA2 mRNA表达水平升高（P<0.01）；与模型组比较，除电针组cPLA2 mRNA外，各治疗组大鼠脊髓组织p-cPLA2蛋白及cPLA2 mRNA表达水平都明显低于模型组（P<0.01）；电针+阻断剂组cPLA2 mRNA表达水平低于电针组（P<0.01）。结论：电针通过抑制cPLA2的活性，进而升高Bcl-2、降低Bax及Caspase-3表达，减少神经细胞的凋亡，达到改善SCI大鼠神经功能的作用。.
Keywords: Apoptosis; Cytosolic phospholipase A2; Electroacupuncture; Spinal cord injury.