小檗碱对胰岛β细胞的保护作用及其机制研究

 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15 μmol/L）、中剂量小檗碱组（MBer组，小檗碱浓度为45 μmol/L）及高剂量小檗碱组（HBer组，小檗碱浓度为100 μmol/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。

Protective effects of berberine in pancreatic islet beta cells

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 cytometry was employed to detect the apoptosis. The activation of PTEN/PI3K/Akt and HNF-1α/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 apoptotic rate increased significantly in Axn group. Berberine treatment reduced the apoptotic rate in LBer group, MBer group and HBer group in a concentration-dependent manner. Compared with Con group, the protein levels of PTEN and cleaved caspase-3 increased, while PI3K and phosphorylation of Akt decreased significantly in Axn group. However, this effect was reversed by berberine in a concentration-dependent manner. Compared with Con group, the activation of HNF-1α/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 impaired 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 inhibiting apoptosis and recovering insulin secretion, thus attenuating the activation of PTEN/PI3K/Akt and HNF-1α/PDX-1 signaling pathways.