电针对大鼠术后认知功能障碍及海马组织HIF-1α表达和神经细胞凋亡水平的影响

目的:观察电针对术后认知功能障碍大鼠学习记忆功能及海马缺氧诱导因子1α(hypoxia inducible factor-1α,HIF-1α)表达、细胞凋亡水平的影响,探讨电针改善术后认知功能障碍的作用机制。方法:将90只老年雄性SD大鼠随机分为假手术组、模型组和电针组,每组30只。每组再按术后干预1、3、7 d分为3个亚组,每亚组10只。模型组和电针组大鼠行肝左叶切除术建立术后认知功能障碍模型,假手术组大鼠仅切开皮肤不切除肝叶。电针组选取"四关"穴("合谷"和"太冲")给予电针干预,疏密波,频率2 Hz/100 Hz,强度1 mA,每天1次,每次20 min。采用Morris水迷宫检测各组大鼠认知功能,实时荧光定量PCR(real-time PCR)法和蛋白免疫印迹法(Western blot)检测海马组织HIF-1α表达,TUNEL法检测海马组织神经细胞凋亡水平。取电针组大鼠海马组织,采用免疫荧光双染色法进行HIF-1α和凋亡细胞的共定位。结果:与假手术组比较,模型组大鼠术后1、3、7 d的逃避潜伏期延长,穿越平台次数减少(均P<0.05);与模型组比较,电针组大鼠术后1、3、7 d的逃避潜伏期缩短,穿越平台次数增多(均P<0.05)。在术后干预3 d时,与假手术组比较,模型组海马组织HIF-1α的mRNA和蛋白表达增加,神经细胞凋亡水平增加(均P<0.05);与模型组比较,电针组海马组织HIF-1α的mRNA和蛋白表达降低,神经细胞凋亡水平降低(均P<0.05)。电针组大鼠海马组织HIF-1α表达与凋亡染色共定位于同一细胞。结论:电针可改善术后认知功能障碍大鼠的认知功能,其机制可能与降低海马组织HIF-1α表达、抑制神经细胞凋亡有关。

Effect of electroacupuncture on cognitive functions,hippocampal HIF-1α and neurons apoptosis in postoperative cognitive dysfunction rats

Objective To observe the effect of electroacupuncture(EA) on learning and memory ability, hippocampal hypoxia inducible factor-1α(HIF-1α) and apoptosis in postoperative cognitive dysfunction(POCD) rats, and to investigate its mechanism underlying improvement of POCD. Methods A total of 90 aged male SD rats were randomized into a sham-operation group, a model group and an EA group, 30 rats in each group, which were further divided into 3 time-point subgroups(1, 3 and 7 days after intevention, 10 rats in each subgroup). In the model group and the EA group, left hepatectomy was adopted to establish the model of POCD. In the sham-operation group, the skin was sectioned and no hepatectomy was operated. In the EA group, EA was applied at "Siguan" "Hegu"(LI 4) and "Taichong"(LR 3)] with dilatational wave, 2 Hz/100 Hz in frequency, 1 mA in intensity, 20 min each time, once a day. Morris water maze test was adopted to observe the cognitive functions. Real-time PCR and Western blot were used to measure the hippocampal level of HIF-1α. TUNEL method was used to evaluate the hippocampal level of neurons apoptosis. Double immunofluorescence labeling was used to detect the colocalization of HIF-1α and apoptosis in the EA group. Results Compared with the sham-operation group, the escape latency was prolonged and the frequency of platform leaping was reduced in the model group(P<0.05) after 1, 3, 7 days of intervention. Compared with the model group,the escape latency was shortened and the frequency of platform leaping was increased in the EA group(P<0.05) after 1, 3, 7 days of intervention. After 3 days of intervention, compared with the sham-operation group, the expressions of HIF-1α mRNA and protein, the level of apoptosis were increased in the model group(P<0.05);compared with the model group,the expressions of HIF-1α mRNA and protein, the level of apoptosis were decreased in the EA group(P<0.05). The colocalization of HIF-1α and apoptosis was observed in same cells in the EA group. Conclusion Electroacupuncture improves cognitive functions in postoperative cognitive dysfunction rats, which may be related to its effect in down-regulating the expression of hippocampal HIF-1α and inhibiting the neurons apoptosis.