二甲双胍对多囊卵巢综合征大鼠胰岛素抵抗的改善作用

Improvement effect of metformin on insulin resistance in rats with polycystic ovary syndrome

目的探究二甲双胍通过磷脂肌醇3-激酶(PI3K)/蛋白激酶B(PKB)/雷帕霉素靶蛋白(mTOR)通路对多囊卵巢综合征(PCOS)大鼠胰岛素抵抗(IR)的改善作用。方法雌性SD大鼠采用皮下注射脱氢表雄酮(DHEA)的造模法建立PCOS大鼠模型,将PCOS模型大鼠随机分为模型组及实验组,各20只,另取20只大鼠皮下注射注射用大豆油0.2 mL作为对照组。实验组灌胃140 mg·kg-1二甲双胍,模型组与对照组灌胃等量生理盐水,每日1次,连续干预15 d。用放射免疫法检测空腹血糖(FBG)及空腹胰岛素(FINS)水平,并计算胰岛素抵抗指数(HOMA-IR);用苏木精-伊红(HE)染色观察大鼠卵巢组织病理变化;用蛋白质印迹法检测大鼠卵巢组织PI3K、PKB、mTOR蛋白表达水平;用酶联免疫吸附试验(ELISA)法检测血清睾酮(T)、卵泡刺激素(FSH)、黄体生成素(LH)水平。结果对照组、模型组及实验组大鼠FBG水平分别为(3.19±0.38),(5.73±0.64),(3.82±0.86)mmol·L-1;FINS水平分别为(11.73±0.26),(23.12±0.25),(15.23±0.22)μg·L-1;HOMA-IR分别为1.69±0.24,5.72±0.46,2.38±0.33;卵巢组织PI3K蛋白相对表达量分别为0.95±0.05,0.37±0.13,0.78±0.12;PKB蛋白相对表达量分别为0.93±0.07,0.08±0.04,0.42±0.14;mTOR蛋白相对表达量分别为0.14±0.06,0.98±0.02,0.37±0.11,差异均有统计学意义(均P<0.05)。模型组大鼠血清T、LH水平均高于对照组,与模型组比较,实验组降低;而血清FSH水平降低,且实验组高于模型组(均P <0.05)。结论二甲双胍可调节PCOS大鼠的性激素水平,改善IR及高雄激素血症,其作用机制可能与活化卵巢组织PI3K/PKB/mTOR通路相关。

Objective To investigate the improvement effect of metformin on insulin resistance(IR) in rats with polycystic ovary syndrome(PCOS) through the phospholipid inositol 3-kinase(PI3K)/protein kinase B(PKB)/rapamycin target protein(mTOR) pathway.Methods Female SD rats were injected with dehydroepiandrosterone(DHEA) to establish the PCOS rat models, the PCOS model rats were randomly divided into the model group and the test group, 20 rats in each group, and another 20 rats were subcutaneously injected with 0.2 mL of soybean oil for injection as the control group.Rats in the test group were treated with metformin(140 mg·kg-1) once daily by gavage, the model group and the control group were given with the same amount of normal saline for 15 d.Radioimmunoassay method was used to detect fasting blood glucose(FBG) and fasting insulin(FINS) levels,and calculate the insulin resistance index(HOMA-IR);Hematoxylin-eosin(HE) staining was used to observe the pathological changes of ovarian tissue in rats;Western blot was used to detect the expression of PI3K,PKB and m TOR protein in rat ovarian tissues;Enzyme-linked immunosorbent assay(ELISA) method was used to detect serum testosterone(T),follicle stimulating hormone(FSH),and luteinizing hormone(LH) levels.Results The FBG levels in the control,model and test groups were(3.19 ± 0.38),(5.73 ± 0.64),and(3.82 ± 0.86) mmol·L-1;FINS levels were(11.73 ± 0.26),(23.12 ± 0.25),and(15.23 ± 0.22) μg·L-1;HOMA-IR were 1.69 ± 0.24,5.72 ± 0.46,2.38 ± 0.33;The relative expression of PI3K protein in ovarian tissues were 0.95 ± 0.05,0.37 ± 0.13,0.78 ± 0.12;The relative expression of PKB protein were 0.93 ± 0.07,0.08 ± 0.04,0.42 ± 0.14;The relative expression levels of m TOR protein were 0.14 ± 0.06,0.98 ± 0.02,and 0.37 ± 0.11,all with significant difference(all P < 0.05).Compared with the control group,the serum T,LH levels of the model group increased,and the test group was lower than the model group;the levels of serum FSH reduced,and the test group was higher than the model group(all P < 0.05).Conclusion Metformin can regulate the level of sex hormones in PCOS rats and improve IR and hyperandrogenemia,and its mechanism may be related to the activation of PI3K/PKB/m TOR pathway in ovarian tissues.