Objectives: To observe the effects of moxibustion on intestinal barrier function and Toll-like receptor 4 (TLR4)/nuclear factor-κB p65 (NF-κB p65) signaling pathway in obese rats and explore the mechanism of moxibustion in the intervention of obesity.
Methods: Fifty-five Wistar rats of SPF grade were randomly divided into a normal group (10 rats) and a modeling group (45 rats). In the modeling group, the obesity model was established by feeding high-fat diet. Thirty successfully-modeled rats were randomized into a model group, a moxibustion group, and a placebo-control group, with 10 rats in each one. In the moxibustion group, moxibustion was applied at the site 3 cm to 5 cm far from the surface of "Zhongwan" (CV 12), with the temperature maintained at (46±1 ) ℃. In the placebo-control group, moxibustion was applied at the site 8 cm to 10 cm far from "Zhongwan" (CV 12), with the temperature maintained at (38±1) ℃. The intervention was delivered once daily for 8 weeks in the above two groups. The body mass and food intake of the rats were observed before and after intervention in each group. Using ELISA methool, the levels of serum triacylglycerol (TG), total cholesterol (TC) and lipopolysaccharide (LPS) were detected and the insulin resistance index (HOMA-IR) was calculated. HE staining was used to observe the morphology of colon tissue. The mRNA expression of zonula occludens-1 (ZO-1), Occludin, Claudin-1, TLR4 and NF-κB p65 in the colon tissue was detected by quantitative real-time PCR; and the protein expression of ZO-1, Occludin, Claudin-1, TLR4 and NF-κB p65 was detected by Western blot in the rats of each group.
Results: Compared with the normal group, the body mass, food intake, the level of HOMA-IR, and the serum levels of TC, TG and LPS were increased in the rats of the model group (P<0.01); those indexes in the moxibustion group were all reduced when compared with the model group and the placebo-control group respectively (P<0.01, P<0.05). Compared with the normal group, a large number of epithelial cells in the mucosa of colon tissue was damaged, shed, and the inflammatory cells were infiltrated obviously in the interstitium in the rats of the model group. When compared with the model group, in the moxibustion group, the damage of the colon tissue was recovered to various degrees and there were few infiltrated inflammatory cells in the interstitium, while, the epithelial injury of the colon tissue was slightly recovered and the infiltrated inflammatory cells in the interstitium were still seen in the placebo-control group. The mRNA and protein expressions of ZO-1, Occludin and Caudin-1 were decreased in the model group compared with those in the normal group (P<0.01). When compared with the model group and the placebo-control group, the mRNA and protein expressions of these indexes were increased in the moxibustion group (P<0.01, P<0.05). In the model group, the mRNA and protein expressions of TLR4 and NF-κB p65 were increased when compared with those in the normal group (P<0.01), and the mRNA and protein expressions of these indexes were reduced in the moxibustion group when compared with those in the model group and the placebo-control group (P<0.01).
Conclusions: Moxibustion can reduce the body mass and food intake, regulate the blood lipid and improve insulin resistance in the rats of obesity. It may be related to alleviating inflammatory response through improving intestinal barrier function and modulating the intestinal TLR4/NF-κB p65 signaling pathway.
目的: 观察艾灸对肥胖大鼠肠道屏障功能及Toll样受体4（TLR4）/核转录因子κB p65（NF-κB p65）信号通路的调控作用，探究艾灸干预肥胖的作用机制。方法: 将55只SPF级7周龄雄性Wistar大鼠随机分为正常组（10只）和造模组（45只），造模组采用高脂饮食喂养建立肥胖大鼠模型。造模成功的30只大鼠随机分为模型组、艾灸组、安慰对照组，每组10只。艾灸组在距离“中脘”3~5 cm处施灸，温度保持在（46±1）℃；安慰对照组在距离“中脘”8~10 cm处施灸，温度保持在（38±1）℃。均每天干预1次，共干预8周。观察各组大鼠干预前后体质量、摄食量；ELISA法测定各组大鼠血清总胆固醇（TC）、三酰甘油（TG）、脂多糖（LPS）水平，计算胰岛素抵抗指数（HOMA-IR）；HE染色法观察各组大鼠结肠组织形态；实时荧光定量PCR法检测各组大鼠结肠闭锁连接蛋白-1（ZO-1）、咬合蛋白（Occludin）、紧密连接蛋白-1（Claudin-1）、TLR4、NF-κB p65 mRNA表达；Western blot法检测各组大鼠结肠ZO-1、Occludin、Claudin-1、TLR4和NF-κB p65蛋白表达。结果: 与正常组比较，模型组大鼠体质量、摄食量、HOMA-IR及血清TC、TG、LPS水平升高（P<0.01）；与模型组和安慰对照组比较，艾灸组大鼠体质量、摄食量、HOMA-IR及血清TC、TG、LPS水平降低（P<0.01，P<0.05）。与正常组比较，模型组大鼠结肠组织黏膜大量上皮细胞损伤脱落，间质内可见明显炎性细胞浸润。与模型组比较，艾灸组大鼠结肠组织损伤有不同程度恢复，间质内可见少量炎性细胞浸润；安慰对照组大鼠结肠组织上皮损伤有少许恢复，间质内可见炎性细胞浸润。与正常组比较，模型组大鼠结肠ZO-1、Occludin、Claudin-1 mRNA和蛋白表达降低（P<0.01），结肠TLR4、NF-κB p65 mRNA和蛋白表达升高（P<0.01）；与模型组和安慰对照组比较，艾灸组大鼠结肠ZO-1、Occludin、Claudin-1 mRNA和蛋白表达升高（P<0.01，P<0.05），结肠TLR4、NF-κB p65 mRNA和蛋白表达降低（P<0.01）。结论: 艾灸可以降低肥胖大鼠体质量、摄食量，调节肥胖大鼠血脂，改善胰岛素抵抗，可能与改善肠道屏障功能、调节肠道TLR4/NF-κB p65信号通路来减轻炎性反应有关。.
Keywords: Toll-like receptor 4 (TLR4); intestinal barrier function; moxibustion; nuclear factor-κB p65 (NF-κB p65); obesity.