小檗碱对胰岛β细胞的保护作用及其机制研究

Protective effects of berberine in pancreatic islet beta cells

目的:探讨小檗碱对胰岛β细胞的保护作用及可能机制。方法:采用四氧嘧啶(Axn)诱导INS-1胰岛β细胞损伤模型,并以不同浓度的硫酸小檗碱进行干预。将细胞分为对照组(Con组)、损伤组(Axn组)、低剂量小檗碱组(LBer组,小檗碱浓度为15μmol/L)、中剂量小檗碱组(MBer组,小檗碱浓度为45μmol/L)及高剂量小檗碱组(HBer组,小檗碱浓度为100μmol/L)。流式细胞术观察各组细胞凋亡情况,Western blotting免疫印迹法分别观察各组PTEN/PI3K/Akt信号通路、HNF-1α/PDX-1信号通路活化情况以及激活型caspase-3的水平;酶联免疫吸附法(ELISA)观察各组基础胰岛素释放及葡萄糖刺激后胰岛素的释放水平。结果:与Con组相比,Axn组凋亡率显著升高,但小檗碱干预后凋亡水平显著降低,且呈浓度依赖性。与Con组相比,Axn组PTEN表达水平明显升高,而PI3K/Akt活性被抑制,激活型caspase-3水平显著升高;而小檗碱处理则能逆转上述PTEN通路的促凋亡作用,且显示出浓度依赖性;与Con组相比,Axn组HNF-1α/PDX-1信号通路活性显著下降,但小檗碱处理则能提高该通路活性,表现出浓度依赖性。与Con组相比,Axn组基础及葡萄糖刺激下胰岛素释放水平均显著降低,而小檗碱处理则能显著恢复上述胰岛素释放水平,呈浓度依赖性。结论:小檗碱对四氧嘧啶损伤的INS-1胰岛β细胞具有保护作用,表现为对其凋亡的抑制与胰岛素分泌功能的恢复,分别与影响细胞内PTEN/PI3K/Akt及HNF-1α/PDX-1信号通路有关。

AIM： To explore the protective effects of berberine （Ber） on islet beta cells and related possible mechanisms. METHODS： The injury of INS-1 cells was induced by treatment with alloxan （Axn）. Berverine was then given at serial concentrations. The cells were divided into control group （ Con）, injury group （ Axn）, low-dose berberine group （LBer）, medium-dose berberine group （MBer） and high-dose berberine group （HBer）. Flow eytometry was em- ployed to detect the apeptosis. The activation of PTEN/PI3K/Akt and HNF-Ict/PDX-1 pathways and the protein level of cleaved caspase-3 were evaluated by Western blotting. The insulin releases under normal or high-glucose stimulation were measured by ELISA. RESULTS： Compared with Con group, the ap0ptotic rate increased significantly in Axn group. Ber- berine treatment reduced the apoptotic rate in LBer group, MBer group and HBer group in a concentration-dependent man- ner. Compared with Con group, the protein levels of PTEN and cleaved caspase-3 increased, while PI3K and phosphoryla- tion of Akt decreased significantly in Axn group. However, this effect was reversed by berberine in a concentration-depend- ent manner. Compared with Con group, the activation of HNF-la/PDX-1 signaling pathway was inhibited in Axn group but recovered by berberine administration. The abilities of releasing insulin under normal or high-glucose stimulation were im- paired in Axn group but recovered by berberine treatment in LBer group, MBer group and HBer group in a concentration- dependent manner. CONCLUSION： Berberine shows protective effects against alloxan-induced damage in beta cells by in- hibiting apoptosis and recovering insulin secretion, thus attenuating the activation of PTEN/PBK/Akt and HNF-1 a/PDX-1 signaling pathways.