长波紫外线照射对HaCaT细胞iNOS/NO表达的影响

目的 探讨不同剂量长波紫外线 （UVA） 照射HaCaT细胞后不同时间点诱导型一氧化氮合成酶（iNOS）的表达情况。方法 1 J/cm2、5 J/cm2和10 J/cm2 UVA照射HaCaT细胞后继续培养24 h、48 h和72 h，倒置相差显微镜下观察细胞形态的变化；分别用RT-PCR、Western印迹和Griess法检测HaCaT细胞iNOS mRNA、蛋白及NO的表达。结果 所有UVA剂量组HaCaT细胞iNOSmRNA在光照后24 h有表达，48 h达高峰，72 h后下降，各时间点间表达量差异有统计学意义（P < 0.05）；1 J/cm2 UVA照射后3个时间点均未见iNOS蛋白表达，而5 J/cm2和10 J/cm2 UVA照射后iNOS蛋白在24 h增加，48 h达高峰且显著高于24 h（P < 0.05），照射后72 h无iNOS蛋白表达。所有UVA剂量组HaCaT细胞NO表达量在24 h升高，48 h显著升高，72 h平稳升高，3个时间点NO表达量均比正常对照组明显增加（P < 0.05）。对照组HaCaT细胞无iNOS mRNA和蛋白表达，NO表达量低。结论 HaCaT细胞iNOS和NO的表达变化与UVA照射存在时间和剂量关系。

Expression of inducible nitric oxide synthase and level of nitric oxide in HaCaT cells after UVA irradiation

Objective To investigate the effects of UVA irradiation on the expression of inducible nitric oxide sgnthase(iNOS)and level of nitric oxide(NO)in HaCaT cells.Methods HaCaT cells were cultured,irradiated with difrerent doses(1,5,1 0 J/cm2)of UVA.After another 24-,48-,72-hour culture,the mRNA and protein expressions of iNOS and level of NO wen measured bv RT-PCR,Westem blot and Griess reagent kit,respectively.Results Atier the irradiation with 1.5 or 10 J/cm2 of UVA,the mRNA expression of iNOS was observed in HaCaT cells at 24 h,reached a peak at 48 h,then decreased at 72 h;significant differences were fcIund between the three time points (all P＜0.05).No expression of iNOS protein was detected in HaCaT cells at any time point after irradiation witll UVA Of 1 J/cm2;meanwhile,with UVA irradiation of 5 and 10 J/cm2,the protein expression of iNOS increased at 24 h,peaked at 48 h,but was undetected at 72 h.In HaCaT cells irradiated with UVA of 1.5 or 10 J/cm2.the level Of NO showed an increase at 24 h.a marked increase at 48 h,and a stable increase at 72 h,and significant differences were noticed between irradiated cells and control cells at three time points(all P＜0.05).In unirradiated HaCaT cells,no expression of iNOS mRNA or protein was observed with a low level of NO.Conclusions The changes in iNOS expression and NO level in HaCaT cells are related to the duration and dose of UVA irradiation.