小檗碱改善3T3-L1脂肪细胞胰岛素抵抗的分子机制

Molecular mechanism for berberine to improve insulin resistance in 3T3-L1 adipocytes

目的研究小檗碱对游离脂肪酸诱导的3T3-L1脂肪细胞胰岛素抵抗的作用，探讨小檗碱改善胰岛素抵抗的分子机制。方法以0．5mmol／L软脂酸诱导3T3-L1脂肪细胞产生胰岛素抵抗，予以小檗碱进行干预，同时以阿司匹林作为阳性对照，用葡萄糖氧化酶法检测培液中的葡萄糖消耗量，以2-脱氧-[^3H]-D-葡萄糖摄入法观察葡萄糖的转运率，用Western印迹检测IκB激酶B（IKKβ）、胰岛素受体底物1（IRS-1）、磷酸肌醇3激酶p85（PI-3K p85），葡萄糖转运子4（Glut4）的蛋白表达和IKKβ 181位丝氨酸（IKKβ Ser181）、IRS-1 307位丝氨酸（IRS-1 Ser307）的磷酸化。结果0．5mmol／L软脂酸作用24h使3T3-L1脂肪细胞葡萄糖消耗降低41％，胰岛素刺激的葡萄糖转运抑制67％，IKKβSer181和IRS-1 Ser307的磷酸化增加，IRS-1和PI-3K p85蛋白的表达减少；同时加入小檗碱或阿司匹林则可逆转上述效应。但软脂酸、小檗碱、阿司匹林对3T3-L1脂肪细胞IKKβ蛋白、Glut4蛋白的表达无明显影响。结论小檗碱可以明显改善游离脂肪酸诱导的胰岛素抵抗，其分子机制可能是通过抑制IKKβ Ser181磷酸化实现的。

Objective To investigate the effect of berberine on insulin resistance induced by free fatty acid in 3T3-L1 adipocytes and the possible molecular mechanism. Methods 3T3-L1 adipocytes were treated with 0.5 mmol/L palmitic acid to induce insulin resistance. Berberine was used for treatment and aspirin for positive control. Glucose oxidase method was employed for measuring the glucose consumption in the medium and 2-deoxy-[^3H ]-D-glucose method was used for the determination of glucose uptake. Western blot was used for the determination of IKB kinase （IKK） [3 Serl81 phosphorylation, insulin receptor substrance-1 （ IRS-1 ） Ser307 phosphoryiation, the protein expression of IKKβ, IRS-1, phosphatidylinositol 3-kinase （PI-3K） p85 and glucose transporter 4 （Glut4）. Results After the treatment with 0. 5 mmol/L of palmitic acid for 24 h, glucose consumption by 3T3-L1 adipocytes was decreased by 41%, insulin-stimulated glucose transport was inhibited by 67%, IRS-1 and PI-3K p85 proteins were reduced, and phosphorylations of IKKβ Ser181 and IRS-1 Ser307 were induced. The above results were reversed by adding berberine or aspirin. But Glut4 and IKKβ protein abundance was not changed during this study. Conclusion Berberine significantly improves insulin resistance induced by free fatty acid in 3T3-L1 adipocytes via inhibiting IKKβ serine phosphorylation.