Objectives: To observe the effect of electroacupuncture (EA) on central nervous inflammatory response in obese rats, so as to explore its mechanisms underlying improvement of obesity.
Methods: Male SD rats were randomly allocated to normal control, model, EA and sham-EA groups (n=15/group). Rats of the normal group were fed with normal diet, and the obesity model was established by feeding the rats with high-fat diet for 8 weeks. EA (2 Hz, 1 mA) was applied to "Zusanli"(ST36), "Zhongwan"(CV12), "Guanyuan"(CV4) and "Fenglong"(ST40), and non-acupuncture points (about 5 mm left to CV4 and CV12 and about 5 mm lateral to ST36 and ST40) for 15 min, once every other day, 3 times a week for 8 weeks (no electrical current was delivered to the non-acupoints). The body weight and anal-nose length in each group were recorded before and after the intervention and Lee's index was calculated. The adipocyte morphology of epididymis was detected after H.E. staining, and the contents of serum tumor necrosis factor α (TNF-α), interleukin (IL)-6, IL-10 and free fatty acid (NEFA) were detected by using enzyme-linked immunosorbent assay (ELISA). The expression levels of TNF-α, IL-6, IL-10 and inducible nitric oxide synthase (iNOS) proteins in the hypothalamus tissue were detected by Western blot, and the immunoactivity of ionized calcium-binding adapter molecule 1 (Iba-1) in hypothalamic microglia was detected by immunohistochemistry. The content of Evans blue in the brain tissue samples was detected by Evans blue assay to evaluate the integrality of blood-brain barrier.
Results: Compared with the normal group, the body mass (BM), Lee's index, contents of serum TNF-α, IL-6 and NEFA, expression levels of hypothalamic TNF-α, IL-6 and iNOS proteins, the immunoactivity level of Iba-1 and the content of Evans blue were significantly increased (P<0.01, P<0.05), while the content of serum IL-10 and the expression of hypothalamic IL-10 protein considerably decreased (P<0.01) in the model group. After the intervention, modeling induced increase of BM, Lee's index, contents of serum TNF-α, IL-6 and NEFA, expression levels of hypothalamic TNF-α, IL-6 and iNOS proteins, the immunoactivity level of Iba-1 and the content of Evans blue, and decrease of serum content and expression level of IL-10 in the hypothalamus were reversed by EA stimulation (P<0.01, P<0.05) but not by non-acupoint stimulation. H.E. staining showed that the adipocytes of epididymis became larger in size and decreased in the number in the model group relevant to the normal group, and became smaller after EA (not non-acupoint) relevant to the model group.
Conclusions: EA can treat obesity, improve body inflammation caused by obesity, and relieve central inflammation by repairing the blood-brain barrier.
目的: 观察电针对肥胖大鼠中枢炎性反应的影响，探讨电针干预肥胖的中枢炎性反应机制。方法: SD大鼠随机选取10只作为正常组给予正常饲料喂养，其余予以高脂饲料喂养8周进行肥胖造模。将造模成功的大鼠随机分为模型组、电针组和非经穴组，每组10只。电针组取“中脘”“关元”及双侧“足三里”“丰隆”进行电针治疗；非经穴组取“关元”和“中脘”向左旁开约5 mm、“足三里”和“丰隆”向外旁开约5 mm处浅刺并夹持电极，不予通电。两组均每次治疗15 min，每周一、三、五进行治疗，共8周。测量各组大鼠干预前后的体质量及肛鼻长，计算Lee’s指数；HE染色法观察各组大鼠附睾脂肪细胞形态；ELISA法检测各组大鼠血清中肿瘤坏死因子α（TNF-α）、白细胞介素6（IL-6）、白细胞介素10（IL-10）、游离性脂肪酸（NEFA）的含量；Western blot法检测各组大鼠下丘脑组织中TNF-α、IL-6、IL-10、诱导型一氧化氮合成酶（iNOS）蛋白表达水平；免疫组织化学法检测下丘脑小胶质细胞离子钙结合衔接分子1（Iba-1）的表达；伊文思蓝染色检测脑组织样本中伊文思蓝含量观察血脑屏障的完整性。结果: 与正常组比较，模型组大鼠脂肪细胞形态变大，体质量、Lee’s指数及血清TNF-α、IL-6、NEFA含量显著升高（P<0.01），血清IL-10含量下降（P<0.01），下丘脑中TNF-α、IL-6、iNOS蛋白表达水平升高（P<0.01），IL-10蛋白表达水平下降（P<0.01），下丘脑Iba-1阳性表达升高（P<0.01），脑组织中伊文思蓝含量明显升高（P<0.05）。与模型组和非经穴组比较，电针组大鼠脂肪细胞形态缩小，体质量、Lee’s指数及血清TNF-α、IL-6、NEFA含量均显著下降（P<0.01，P<0.05），血清IL-10含量上升（P<0.01），下丘脑中TNF-α、IL-6、iNOS蛋白表达水平下降（P<0.01），下丘脑IL-10的表达水平上升（P<0.01），下丘脑Iba-1阳性表达下降（P<0.01），脑组织中伊文思蓝含量下降（P<0.05）。结论: 肥胖会伴有神经炎性反应的发生，电针可以治疗肥胖并改善因肥胖引起的机体炎性反应，还能通过修复血脑屏障来缓解中枢炎性反应。.
Keywords: Blood-brain barrier; Central inflammation; Electroacupuncture; Obesity.