Objective: To observe the effect of electroacupuncture(EA)at "Baihui"(GV20) and "Shenting" (GV24) on the expression of melatonin synthesis rate-limiting enzyme-arylalkylamine N-acetyltransferase(AANAT)in pineal gland of rats with focal cerebral ischemia-reperfusion injury, so as to explore the mechanism of EA underlying improving ischemia-reperfusion injury.
Methods: Forty-eight SD rats were randomly divided into sham operation, model, EA and non-acupoint groups, with 12 rats in each group. The focal cerebral ischemia-reperfusion injury rat model was established by occlusion of the middle cerebral artery. Rats of the EA group received EA at GV20 and GV24, while those in the non-acupoint group received EA at non-acupoints below the costal margins on both sides for 20 min, once daily for 7 days. The neurological deficit score (0 to 4 points) was given after successful modeling according to Longa's method. Morris water maze test was used to assess the cognitive function of rat. ELISA was used to detect the plasma melatonin content, and PCR and Western blot were used to detect the mRNA and protein expressions of AANAT in the pineal gland, separately. Immunofluorescence staining was used to detect the activation of astrocytes and neuronal injury in the hippocampus.
Results: After focal cerebral ischemia-reperfusion injury and compared with the sham operation group, the neurological deficit score, the escape latency, and the expression of GFAP were significantly increased (P<0.01)，while the times of platform quadrant crossing, the secretion of melatonin at 24:00，AANAT mRNA and protein expression levels and NeuN protein expression were significantly down-regulated (P<0.01). After EA at GV20 and GV24, the above-mentioned indexes all reversed in the EA group relative to the model group, and there were significant differences between the two groups(P<0.01). Compared with the model group, the changes of the abovementioned indexes in the non-acupoint group were not statistically significant (P>0.05).
Conclusion: EA at GV20 and GV24 can alleviate neurological deficit and improve cognitive function in cerebral ischemia-reperfusion rats，which may be related to its effects in up-regulating endogenous melatonin levels, inhibiting the activation of astrocytes and protecting damaged neurons in the hippocampus.
目的：观察电针对大鼠血清褪黑素含量及松果体褪黑素合成限速酶―芳烷胺-N-乙酰转移酶(AANAT)表达的影响，探讨电针“百会”“神庭”减轻大鼠脑缺血再灌注损伤的机制。方法：SD大鼠随机分为假手术组、模型组、电针组和非经非穴组，每组12只。采用大脑中动脉闭塞法制备局灶性脑缺血再灌注损伤模型。电针组取“百会”“神庭”，非经非穴组取双胁下非经非穴点，每日电针20 min，1次/d，连续干预7 d。Longa法评估神经功能缺损情况，水迷宫实验检测各组大鼠认知功能，ELISA法检测血浆褪黑素含量，PCR及Western blot法检测大鼠松果体AANAT mRNA及蛋白的表达水平，免疫荧光法检测海马CA1区星形胶质细胞活化情况以及神经元损伤情况。结果：和假手术组比较，模型组Longa评分、水迷宫实验逃避潜伏期显著增高(P<0.01)，穿越平台次数减少(P<0.01)；夜间24:00褪黑素分泌显著降低(P<0.01)；松果体内AANAT mRNA和蛋白表达水平显著降低(P<0.01)；海马CA1区GFAP(星形胶质细胞标记物)阳性表达显著增加(P<0.01)，NeuN(神经元标记物)阳性表达显著下降(P<0.01)。和模型组比较，电针组Longa评分、水迷宫实验逃避潜伏期显著降低(P<0.01)，穿越平台次数增加(P<0.01)，夜间24:00褪黑素分泌显著升高(P<0.01)，松果体内AANAT mRNA和蛋白的表达升高(P<0.01)，海马CA1区GFAP阳性表达降低(P<0.01)，NeuN阳性表达升高(P<0.01)。与模型组比较，非经非穴组以上各指标无明显变化(P>0.01)。结论：电针“百会”“神庭”可以减轻脑缺血再灌注损伤模型大鼠神经功能和认知功能损伤，其机制可能和调控内源性褪黑素表达水平，抑制海马CA1区星形胶质细胞活化以及保护受损神经元有关。.
Keywords: Astrocyte; Cerebral ischemia-reperfusion injury; Electroacupuncture; Melatonin.