余甘子水提物对糖尿病模型大鼠脂质代谢紊乱和胰岛素抵抗的改善作用及机制研究

Study on the improvement effects and mechanism of Phyllanthus emblica water extracts on insulin resistance and lipid metabolism disorder in diabetic model rats

目的 探讨余甘子水提物改善糖尿病模型大鼠脂质紊乱和胰岛素抵抗(IR)的作用及可能机制。方法 雄性SD大鼠进行IR造模,并随机分为模型组、阳性对照组和余甘子水提物高、中、低剂量组,另设空白组,每组各10只。余甘子水提物高、中、低剂量组大鼠分别给予800、400、200 mg/kg余甘子水提物稀释液,阳性对照组大鼠给予2.7 mg/kg吡格列酮溶液,空白组和模型组大鼠给予等体积生理盐水,每日灌胃1次,连续4周。观察大鼠一般状态并测定其体质量及血清脂代谢指标[三酰甘油(TG)、总胆固醇(TC)、低密度脂蛋白胆固醇(LDL-C)、高密度脂蛋白胆固醇(HDL-C)]水平;应用酶联免疫吸附法测定并计算其血清空腹胰岛素(FINS)、胰岛素抵抗指数(IRI)及胰岛素敏感指数(ISI);通过苏木素-伊红染色观察其肝组织病理形态;通过碘酸-雪夫(PAS)染色法观察其肝组织糖原表达情况,并计算染色面积;采用Western blot法检测其肝组织中氧化物酶增殖体激活受体γ(PPARγ)、核因子κB(NF-κB)、磷酸化腺苷酸活化蛋白激酶(p-AMPK)蛋白表达。结果 与空白组比较,模型组大鼠多饮、多食、多尿现象明显,其血清中TC、TG、LDL-C、FINS水平和IRI显著升高(P<0.05),ISI显著降低(P<0.05);肝小叶结构明显紊乱,肝细胞多发变形、肿大,且有许多脂质沉积和脂肪空泡;糖原PAS染色面积显著减小(P<0.05);PPARγ、p-AMPK蛋白表达水平显著降低(P<0.05),NF-κB蛋白表达水平显著升高(P<0.05)。与模型组比较,余甘子水提物高、中剂量组大鼠精神状态、肝组织病理形态及糖原表达情况均明显好转,以上指标水平均显著逆转(P<0.05)。结论 余甘子水提物可能通过激活PPARγ/AMPK/NF-κB信号通路,改善IR模型大鼠的糖脂代谢紊乱、肝功能和IR。

OBJECTIVE To investigate the improvement effects and possible mechanism of Phyllanthus emblica water extracts on lipid metabolism disorder and insulin resistance(IR) in diabetic model rats. METHODS IR model of male SD rats was established and randomly divided into model group, positive control group, P. emblica water extracts high-dose, medium-dose and low-dose groups, and another blank group was set up, with 10 rats in each group. P. emblica water extracts high-dose, mediumdose and low-dose groups were given P. emblica water extract diluent at the doses of 800, 400 and 200 mg/kg respectively;positive control group was given pioglitazone solution 2.7 mg/kg;blank group and model group were given the same volume of normal saline, by intragastrical administration, once a day, for consecutive 4 weeks. The general state of rats was observed, and the body mass and the levels of serum lipid metabolism indexes [triacylglycerol(TG), total cholesterol(TC), low-density lipoprotein cholesterol(LDL-C), high-density lipoprotein cholesterol(HDL-C)] were measured;fasting insulin of serum(FINS), insulin resistance index(IRI) and insulin sensitivity index(ISI) were measured and calculated by enzyme-linked immunosorbent assay(ELISA). The pathological morphology of liver tissue was observed by hematoxylin-eosin staining;the expression of glycogen in the liver was observed by periodic acid-Schiff staining, and the staining area was calculated;the protein expressions of peroxisome proliferator-activated receptor(PPAR), nuclear factor κB(NF-κB) and AMP-activated protein kinase(AMPK)were detected by Western blot. RESULTS Compared with blank group, the rats in the model group had obvious symptoms of polydipsia, polyphagia and polyuria, and the serum levels of TC, TG, LDL-C, FINS and IRI were significantly increased(P<0.05), while ISI was significantly reduced(P<0.05);the structure of hepatic lobule was obviously disordered, the liver cells were deformed and enlarged, and there were many lipid deposits and fat vacuoles;PAS staining area of glycogen was significantly reduced(P<0.05);the protein expression levels of PPARγ and p-AMPK were significantly decreased(P<0.05), while the protein expression level of NF-κB was significantly increased(P<0.05). Compared with model group, the mental state of rats, liver histopathological morphology and glycogen expression were improved significantly in P. emblica water extracts high-dose and medium-dose groups;the levels of the above indicators were significantly reversed(P<0.05). CONCLUSIONS P. emblica water extracts may improve glucose and lipid metabolism disorders, liver function and IR in IR model rats, and regulate IR by activating the PPARγ/AMPK/NF-κB signaling pathway.