Ramkumar Kunga M, Lee Ae Sin, Krishnamurthi Kannan, Devi Sivanesan Saravana, Chakrabarti Tapan, Kang Kyung Pyo, Lee Sik, Kim Won, Park Sung Kwang, Lee Nae Ho, Rajaguru Palanisamy
Department of Internal Medicine, Research Institute of Clinical Medicine and Diabetes Research Center, Chonbuk National University Medical School, Jeonju, South Korea.
Cell Physiol Biochem. 2009;24(5-6):429-40. doi: 10.1159/000257480. Epub 2009 Nov 4.
The present study evaluated the molecular mechanism of antidiabetic property of G. montanum leaf extract (GLEt) against alloxan-induced apoptotic cell death in rat insulinoma cells (RINm5F). The pre-treatment of GLEt (5 microg and 10 microg/ml) resulted in significant decrease in intracellular Ca(2+) concentration, nitric oxide (NO) production along with increase in mitochondrial membrane potential in alloxan (7mM/ml) treated cells. Further GLEt reduced apoptosis by inhibiting the release of cytochrome c and subsequent cleavage of PARP and caspase-3. The immunochemical staining of 8-hydroxydeoxyguanosine (8-OHdG) also evidenced the suppression of oxidative stress by GLEt. The cell cycle analysis, annexin-V labelling assay and TUNEL assay showed the suppression of apoptosis by the treatment of GLEt. Moreover, GLEt significantly increased the cellular antioxidant levels and decreased the lipid peroxides in alloxan-treated RINm5F cells. Taken together, these findings suggest that G. montanum protects pancreatic beta-cells against reactive oxygen species (ROS) by counteracting with mitochondrial membrane permeability and inhibition of the apoptotic pathway.
本研究评估了山地瓜叶提取物（GLEt）对四氧嘧啶诱导的大鼠胰岛素瘤细胞（RINm5F）凋亡性细胞死亡的抗糖尿病特性的分子机制。用GLEt（5微克和10微克/毫升）预处理导致在四氧嘧啶（7毫摩尔/毫升）处理的细胞中细胞内Ca(2+)浓度、一氧化氮（NO）生成显著降低，同时线粒体膜电位增加。此外，GLEt通过抑制细胞色素c的释放以及随后的PARP和半胱天冬酶-3的裂解来减少细胞凋亡。8-羟基脱氧鸟苷（8-OHdG）的免疫化学染色也证明了GLEt对氧化应激的抑制作用。细胞周期分析、膜联蛋白-V标记测定和TUNEL测定显示GLEt处理可抑制细胞凋亡。此外，GLEt显著提高了四氧嘧啶处理的RINm5F细胞的细胞抗氧化水平并降低了脂质过氧化物。综上所述，这些发现表明山地瓜通过抵消线粒体膜通透性和抑制凋亡途径来保护胰腺β细胞免受活性氧（ROS）的影响。
