中文摘要：

目的对比观察了长波紫外线（uvA）照射对培养人表皮黑素细胞与真皮成纤维细胞过氧化氢酶（CAT）蛋白表达以及DNA氧化产物8一羟基一脱氧鸟苷（8-oxo—dG）生成的影响，旨在认识除生成黑素以外黑素细胞具有的抗氧化机制。方法建立人成纤维细胞及人黑素细胞原代和传代培养。培养细胞给予不同剂量（0，3，5，25J，cm2）UVA照射，孵育3h后，用间接免疫荧光的方法检测CAT和8-oxo—dG的水平。结果3J／cm。UVA照射后，成纤维细胞CAT蛋白表达与假照射组对比明显增加（尺0．001），8-oxo—dG荧光强度差别无统计学意义（降0．918）；黑素细胞中CAT蛋白表达与假照射组对比明显减少（P〈0．001），8-oxo—dG荧光强度显著增加（P=0．002）。结论表皮黑素细胞对氧化应激存在固有的敏感性，且暴露UVA介导的氧化应激后黑素细胞缺乏适应性上调CAT表达，这些机制可能关系到白癜风皮损黑素细胞氧化损伤的发生。

英文摘要：

Objective To investigate the changes of catalase expression and oxidative DNA product 8-hydroxy- deoxyguanosine （8-oxo-dG） in cultured melanocytes and fibroblasts in the presence or absence of UVA-mediated oxidative stress, further understanding the antioxidative activities of melanocytes except for melanin production. Methods Establish- ment of primary fibroblast cultures from adult foreskin tissue was achieved in this study. Primary melanocyte （HEMC-LP） was purchased from Cascade Co, USA and subcultured in complete M254 medium. The cells grown in cover slides were irradiated by different doses of UVA （0,3,5,25 J/cm2）. The levels of 8-oxo-dG and catalase protein in both treated and untreated cells were detected by an indirect immunofluorescence technique. Results The level of catalase protein was increased in the fibroblasts exposed to 3 J/cm2 UVA radiation in comparison with the sham-irradiated control （P〈0.001）, no difference of 8-oxo- dG immunostaining was found between irradiated and sham-irradiated group （P=0.918）. Whereas, the level of catalase protein was significantly decreased in the melanocytes exposed to 3 J/cm2 UVA radiation comparing with the sham-irradiated control （P〈0.001）, UVA-irradiated melanocytes exhibited more 8-oxo-dG immunostaining than did sham-irradiated cells （P=0.002）. Conclusion Human melanocytes are more susceptible to exogenous oxidative stress than fibroblast, adaptive upregulation of catalase is absent in melanocytes under UVA-mediated oxidative stress, which contributes to oxidative damage of melanocytes seen in vitiligo.