Objective: To observe the effect of electroacupuncture (EA) on learning-memory ability, ultrastructural changes of hippocampal CA1 neurons, reactive oxygen species (ROS) level, Nod-like receptor protein 3 (NLRP3) and auto-phagy-related proteins expression in the hippocampus of vascular dementia (VD) rats, so as to reveal its partial mechanisms in treating VD.
Methods: Male SD rats were randomly divided into sham operation, model, and EA groups (n=10 rats in each group). The VD model was established by permanent ligation of bilateral common carotid arteries. Rats of the EA group were treated with EA at "Baihui" (GV20), "Dazhui" (GV14) and bilateral "Shenshu" (BL23) for 30 min, once a day for 4 weeks. Morris water maze was used to evaluate the learning and memory ability of rats before modeling, 4 weeks after modeling and after intervention. Transmission electron microscopy (TEM) was used to observe the ultrastructural changes of hippocampal CA1 neurons. The level of ROS in hippocampus was detected by DCFH-DA fluorescence probe. The expressions of NLRP3, autophagy-related protein Beclin1 and microtubule-associated protein 1 light chain 3 (LC3) were measured by Western blot.
Results: In comparison with the sham operation group, the average escape latency of rats in the model group was prolonged (P<0.01), and the times of crossing the original platform were reduced (P<0.05), the level of ROS, the expression levels of LC3-Ⅱ/LC3-Ⅰ ratio, Beclin1 and NLRP3 proteins in hippocampus were increased (P<0.01, P<0.05) in the model group. After EA intervention, the average escape latency of rats was significantly shortened (P<0.01), and the times of crossing the original platform were increased (P<0.05), the level of ROS, the expression levels of LC3-Ⅱ/LC3-Ⅰ ratio, Beclin1 and NLRP3 proteins in hippocampus were decreased (P<0.01, P<0.05) in the EA group compared with those of the model group. Outcomes of TEM showed that CA1 neurons in the hippocampus were damaged, chromatin aggregation, mitochondria pyknosis, cristae structure disorder, rough endoplasmic reticulum expanded and degranulated, the number of free ribosomes decreased, and autophagy could be seen in the model group, which were milder in the EA group.
Conclusion: EA at GV20, GV14 and BL23 can improve the learning and memory abilities of VD rats, alleviate the ultrastructural damage of neurons in hippocampal CA1 area, and repair the damaged neurons. The mechanism may be related to the reduction of ROS level, LC3-Ⅱ/LC3-Ⅰ ratio, NLRP3 and Beclin1 protein expression, the decrease of neuronal autophagy, inhibition of activation of NLRP3 inflammasome and alleviation of central inflammatory response.
目的：观察电针对血管性痴呆大鼠学习记忆功能、海马CA1区神经元超微结构、活性氧(ROS)水平、NOD样受体蛋白3(NLRP3)及自噬相关蛋白表达的影响，探讨其部分作用机制。方法：雄性SD大鼠随机分为假手术组、模型组和电针组，每组10只。采用双侧颈总动脉永久性结扎法制备血管性痴呆大鼠模型。电针组选取“百会”“大椎”及双侧“肾俞”进行电针治疗，每次30 min，1次/d，连续4周。造模前、造模4周后及治疗后采用Morris水迷宫法评估各组大鼠学习记忆功能；治疗后用透射电镜观察海马CA1区神经元超微结构，DCFH-DA荧光探针法检测海马ROS水平，Western blot法检测海马NLRP3及自噬相关蛋白Beclin1、微管相关蛋白1轻链3(LC3)的表达。结果：与假手术组比较，模型组大鼠逃避潜伏期延长(P<0.01)，穿越原平台次数减少(P<0.05)，海马ROS阳性率、NLRP3及Beclin1蛋白表达、LC3-Ⅱ/LC3-Ⅰ比值明显升高(P<0.01，P<0.05)；治疗后与模型组比较，电针组大鼠逃避潜伏期明显缩短(P<0.01)，穿越原平台次数增多(P<0.05)，海马ROS阳性率、NLRP3及Beclin1蛋白表达、LC3-Ⅱ/LC3-Ⅰ比值明显降低(P<0.01，P<0.05)。与假手术组比较，模型组大鼠海马CA1区神经元损伤，染色质聚集，线粒体减少固缩，嵴结构紊乱，粗面内质网扩张、脱颗粒，游离核糖体数量减少，可见自噬体；与模型组比较，电针组大鼠海马CA1区神经元结构较清晰，线粒体数量增加，结构损伤减轻，偶见部分嵴结构紊乱、断裂，游离核糖体数量增多，内质网结构较好，未见明显自噬体。结论：电针“百会”“大椎”“肾俞”能缓解血管性痴呆大鼠学习记忆障碍，改善海马CA1区神经元超微结构，修复受损神经元，其机制可能与电针降低海马ROS水平、LC3-Ⅱ/LC3-Ⅰ比值及NLRP3、Beclin1蛋白表达，降低神经元过度自噬水平，抑制NLRP3炎性小体的激活，减轻中枢炎性反应有关。.
Keywords: Autophagy; Electroacupuncture; Nod-like receptor protein 3; Reactive oxygen species; Vascular dementia.