纳米银联合放疗对大鼠胶质瘤内iNOS表达和NO水平的影响

目的:研究局部使用纳米银联合放疗对大鼠胶质瘤内诱导型一氧化氮合酶(iNOS)表达和一氧化氮(NO)含量的影响。方法:将C6细胞接种于大鼠右侧尾状核,建模后第8 d,将荷瘤鼠随机分成放疗对照组和纳米银联合放疗组,分别立体定向注入等体积的去离子水及20μg的纳米银,并行单次电离辐射。观察放疗后瘤组织形态学变化,免疫组织化学法检测iNOS蛋白表达,硝酸还原酶法测定NO含量。结果:瘤组织放疗后细胞排列紊乱、密度减少。放疗后6 h胶质瘤内iNOS即有表达,随着时间的延长,iNOS表达进一步增强。放疗后6 h和24h,纳米银联合放疗组iNOS活性均较放疗对照组增高,差异有统计学意义(P<0.01或P<0.001);NO含量的变化与iNOS变化规律基本一致。结论:纳米银联合放疗能够增强iNOS表达,促进NO生成,瘤组织iNOS表达和NO含量改变可能在纳米银联合放疗杀伤胶质瘤细胞的过程中发挥一定的作用。

Effect of nanosilver in combination with radiotherapy on the iNOS expression and NO level in rat glioma

Objective: To study the effect of nanosilver combined with radiotherapy on inducible nitric oxide synthase(iNOS) expression and nitric oxide(NO) content in rat glioma.Methods: C6 glioma cells were transplanted into the right caudate nucleus.Eight days after inoculation,the tumor-bearing animals were randomly divided into irradiated control group and combined treatment group,which received an intratumoral injection of deionized water or the same volume of nanosilver(20 μg),followed by a single dose of ionizing radiation.The tumor histological changes were observed after radiotherapy,the expression of iNOS protein was examined by immunohistochemistry,and the content of NO was determined using nitrate reductase method.Results: The tumor cells arranged in disorder and the cellular density decreased following ionizing radiation.iNOS activity was expressed 6 h postirradiation,and it was further enhanced with time.Furthermore,compared with that in the irradiated control group,iNOS expression increased significantly in the combined treatment groups at 6 h and 24 h after irradiation(P<0.01 or P<0.001);the change of NO content was consistent with that of iNOS activity.Conclusion: The combination of nanosilver with radiotherapy can enhance the expression of iNOS and promote the formation of NO,indicating that the change of iNOS expression and NO content in the tumor tissue may play a role in the anti-glioma process of nanosilver in conjunction with ionizing radiation.