内毒素诱导大鼠胰岛细胞凋亡作用

Effets of endotoxin on apoptosis of pancreatic islet cells in rats

目的 探讨内毒素 (L PS)对大鼠胰岛细胞凋亡作用的机制。方法 观察腹腔注射 2 mg/ kg L PS的大鼠血清胰腺 NO含量动态变化 ;用原位杂交方法检测胰岛细胞诱生型一氧化氮合酶 (i NOS) m RNA;采用单细胞凝胶电泳和DNA凝胶电泳技术 ,分析外源硝普钠 (NO供体 )和 L PS离体条件下对胰岛细胞的损伤。结果 注射 PL S6 h,大鼠血清NO水平明显升高并持续到 3d。胰腺 NO含量 6 h升高 ,12 h达峰值 ,2 4h恢复至正常。胰岛细胞 i NOSm RNA表达 ,6 h开始升高 ,12 h明显增强。体外试验显示 ,外源 NO明显引起胰岛细胞 DNA断裂 ,出现慧星尾和凋亡梯状带 ,并呈剂量依赖关系。高浓度 NO(6 0 mmol/ L SNP)胰岛细胞 DNA随机降解。L PS离体条件下 ,对胰岛细胞损伤作用不明显。结论 内毒素通过整体作用刺激炎症细胞浸润胰岛并诱导 i NOS表达 ,产生

Objective To explore the mechanism of effects of endotoxin (LPS) on apoptosis of pancreatic islet cells in rat.Methods After the model of endotoxemia was established in rat with intraperitoneal injection of LPS (2mg/kg),the changes of nitric oxide (NO) level in serum and pancreas were dynamically determined.The expression of inducible nitric oxide synthase (iNOS) was also observed by situ hybridization in the islet,Moreover,DNA damage in islet cells by the external donor of NO (sodium nitroprusside) and LPS in vitro with single cell gel electrophoresis and agarose gel electrophresis of DNA were also evaluated.Results NO level in serum was significantly increased at the 6th,and persisted to the 3rd day after injection of LPS,the NO in pancreas was also elevated,but recovered to the normal at 24h.The expression of iNOS in pancreatic islet also began to enhance at the 6th and significantly enhanced at the 12th after endotoxemia.In vitro experiment showed that exogenous NO markedly caused the damage of DNA in islet cells,but LPS did not exert the same effects.Conclusion The mechanism of the effcts of endotoxin on apoptosis of islet cells might stimulate the expression of iNOS in inflammatory or non-inflammatory cells that generates the NO inducing the DNA damage of islet cells.