杨桃根中DMDD基于TLR4靶标改善胰岛素抵抗的作用及分子机制研究

Improving insulin resistance (IR) which exists in the whole process of Type 2 Diabetes Mellitus (T2DM) play a significant role in preventing T2DM happening. DMDD which's separated from the Chinese Tradition Medicine Averrhoa carambola L. root had a good hypoglycemic and improving lipid metabolism effect. Unfortunately, its mechanism remains largely unknown. Now, reducing free fatty acids (FFAs) by inhibition TLR4 signaling pathway has become an important way of improving IR. We discovered that DMDD not only have the hypoglycemic effect, but also can decrease the content of plasma FFAs, TG, TC and inhibit the expression of TLR4. Thus, we conjecture that may be associated with its improving IR through ameliorating lipid metabolism by restraining the activation of TLR4 and its downstream signal transduction pathway. In this research, to expound DMDD explicit cellular mechanism on TLR4, we will investigate its effect on improving IR and decreasing FBG, FFAs, TG and TC, etc. in vivo and vitro using Western blot, PCR, ELISA, and so on. That will provide a good experimental basis for further mechanism research via TLR4 on DMDD, and that would be useful to make clear the funtion of TLR4 in improving IR.

胰岛素抵抗(IR)贯穿2 型糖尿病(T2DM)始终，改善IR 是防治T2DM 关键之一。从传统中药杨桃根中分离得到的化合物DMDD具有良好降血糖、改善脂质代谢和IR作用，但作用机制尚未完全明确。目前，通过抑制TLR4活性，降低FFAs已成为改善IR的重要途径。我们研究发现，DMDD不仅能降血糖、而且还能下调血浆FFs、TG、TC含量，抑制TLR4的表达，推测它可能是通过抑制TLR4及其下游信号传导通路的活性、改善脂质代谢这一途径来改善IR。因此，本项目中我们从体外，以不同FFAs诱导3T3-L1脂肪细胞、骨胳肌细胞及MIN6细胞构建IR模型；体内采用高脂饮食诱导IR及敲除TLR4基因的小鼠为模型，采用HE染色、免疫组化、ELISA、PCR等实验技术，系统地研究DMDD对IR的作用，阐明它对TLR4信号传导通路的调控机制，对明确TLR4靶点在改善IR中的作用具有重要意义。

本课题研究表明，杨桃根环已二酮能显著降低高脂饮食引起的胰岛素抵抗小鼠的空腹血糖，改善胰岛素抵抗；对血清中TC、TG及FFAs等脂质起到调节作用；调节脂肪细胞因子TNF-α、IL-6、瘦素、抵抗素等的分泌；降低组织中MDA的含量，增加SOD、GSH-Px的水平。减轻胰岛素抵抗小鼠肝脏、胰腺、脂肪组织的病理性损伤，抑制小鼠胰腺组织及MIN6细胞中Caspase-3，Caspase-8，Caspase-9及Bax等蛋白的表达，减少细胞凋亡，改善胰岛细胞功能。杨桃根环已二酮通过抑制肝脏、脂肪组织及MIN6细胞中TLR4、Myd88、NF-κB蛋白的表达，发挥多靶点的治疗作用。