热休克蛋白70抑制大鼠颅脑损伤诱生型一氧化氮合酶mRNA的表达

Heat shock protein 70 inhibited inducible nitric oxide synthase gene expression in infectious cerebral injury in rat

目的 探讨热休克蛋白 70 (HSP70 )对大鼠感染性脑损伤 (感脑 )诱生型一氧化氮合酶(iNOS)的表达及一氧化氮 (NO)合成的影响。方法 将大鼠 72只随机分为正常对照组、感染性脑损伤组和热休克处理组 ,每组又分为 4、8、2 4h共 3个时间点。采用百日咳菌液通过左颈内动脉注入制成大鼠感染性脑损伤模型 ,用Western印迹杂交技术检测各组各时间点的HSP70的表达 ,同时用原位杂交方法检测各组iNOSmRNA的表达及Griess法测定各组的NO含量的变化。结果 Western印迹杂交分析结果表明 ,大鼠感脑各组及正常组有一定量的HSP70表达 ,而热休克处理组的HSP70的量明显高于感脑组 (P <0 .0 1)。原位杂交结果提示iNOS在感脑的大脑皮质神经细胞中 ,8h开始表达 ,可见明显的杂交信号 ,而热休克处理组仅有少量的阳性颗粒。NO含量在感脑组 4、8、2 4h均明显增高 ,以 8h为最明显 ,与正常对照组比较 ,差异均有非常显著性 (P <0 .0 1) ,但在热休克处理组中 ,NO含量明显降低。结论 热休克反应通过HSP70合成增加抑制大鼠感染性脑损伤iNOSmRNA的表达及NO的合成 。

Objective To study the effects of heat shock protein 70 (HSP70) on inducible nitric oxide synthase (iNOS) expression and nitric oxide (NO) synthesis in infectious cerebral injury in rat. Methods The infectious cerebral injury model was developed by injection of Pertussis Bacilli (PB) suspension via the left internal carotid artery. A total of 72 rats were divided randomly into 3 groups: normal saline control group (NS group), infection cerebral injury group (PB group) and HSP70 pretreatment group (HSP group). The animals were decapitated at 4 h, 8 h and 24 h after injection of PB or NS. HSP70 expression in brain tissue was detected by using Western blot analysis. iNOS mRNA expression in brain tissue was determined by using in situ hybridization method and NO in the brain homogenate was determined by using Griess method. Results Western blot analysis showed HSP70 in brain tissue elevated after heat shock response (HSR), whereas the level of HSP70 in the HSP group was significantly higher than in the PB group ( P <0.01). The signals of iNOS mRNA expression were observed in NS group, PB group and HSP group at 4th h. Hybridization signals in the PB group were significantly stronger than those in the HSP group at 8th h and 24th h. Similarly, the concentration of NO in the PB group was significantly increased, while decreased in the HSP group ( P <0.01). Conclusion The HSR might inhibit iNOS mRNA expression and the increase of NO, which might be associated with the induction of HSP70 synthesis in brain tissue, suggesting that HSP70 may be protective against infectious cerebral injury. [