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目的 观察枸杞多糖对中波紫外线(UVB)辐射后人角质形成(HaCaT)细胞的氧化损伤及p38丝裂原活化蛋白激酶(p38 MAPK)、半胱氨酸蛋白酶-8(caspase-8)、半胱氨酸蛋白酶-3(caspase-3)、B细胞淋巴瘤因子2(Bcl-2)表达的影响.方法 超声辅助水提法制备枸杞多糖(LBP)粉末,体外培养HaCaT细胞,随机分为空白对照组、UVB照射组(UVB 30mJ/cm2辐射40min)、UVB+ LBP组(UVB 30mJ/cm2辐射40min+LBP 1mg/mL),照射前12h加入LBP,照射结束后继续培养20h,倒置显微镜观察细胞形态;MTS法检测各组细胞吸光度值(A值);酶生化法检测超氧化物歧化酶(SOD)活力、过氧化氢酶(CAT)活力和谷胱甘肽过氧化物酶(GSH-Px)含量和丙二醛(MDA)含量;Western blot法测定各组细胞p38MAPK,caspase-8,caspase-3和Bcl-2的表达水平.结果 与对照组相比,UVB照射组细胞形态明显异常,漂浮的死细胞明显增多;与UVB照射组相比,UVB+ LBP组细胞的形态趋于正常,漂浮的死细胞明显减少.UVB照射组较对照组细胞吸光度(A值)明显降低(P＜0.05);UVB+ LBP组细胞吸光度较UVB照射组明显升高(P＜0.05).UVB照射组SOD活力、CAT活力、GSH-Px含量较对照组降低,MDA含量较对照组升高(P＜0.05);UVB+ LBP组细胞SOD活力、CAT活力、GSH-Px含量较UVB照射组升高,MDA含量较UVB照射组降低(P＜0.05).UVB照射组p38 MAPK,caspase-8,caspase-3蛋白表达量明显高于对照组,Bcl-2表达量明显低于对照组(P＜0.05);与UVB照射组相比,UVB+ LBP组HaCaT细胞p38MAPK,caspase-8,caspase-3表达水平降低,Bcl-2表达水平升高(P＜0.05).结论 枸杞多糖可抑制UVB辐射后HaCaT细胞的氧化损伤,并下调p38MAPK,caspase-8,caspase-3及上调Bcl-2的表达水平.“,”Objective To investigate the effects of lycium barbarum polysaccharide (LBP) on oxidative damage and expression levels of p38 mitogen activated protein kinase (p38MAPK),cysteine proteinase 8 (caspase-8),cysteine proteinase 3 (caspase-3) and B cell lymphoma factor 2 (Bcl-2) in UVB-irradiated HaCaT cells.Methods LBP powder was obtained with ultrasonic assisted water extraction.HaCaT cell cultures were randomly divided into 3 groups,blank control,UVB radiation (30mJ/cm2 radiation 40min UVB) and UVB + LBP groups (UVB 30mJ/cm2 radiation 40min + LBP lmg/mL).Twelve hours prior to UVB radia tion,LBP was added into the culture medium,followed by collection of cells 20 hours after radiation.The morphology of cells was observed with an inverted microscope;Cell proliferation (A value) was determined with MTS;The activities of SOD and CAT,and GSH-Px and MDA content were assessed using enzyme linked immunosorbent assay;the expression levels of p38MAPK,caspase-8,caspase-3 and Bcl-2 were determined with Western blot.Results Compared with normal controls,UVB radiation markedly changed morphology of HaCaT cells and increased the number of floating dead cells.In contrast,LBP treatment almost normalized the morphology of HaCaT cells and significantly decreased the number of floating dead cells in UVB-irradiated HaCaT cells.The A value in UVB radiation group was significantly lower (P ＜ 0.05) than that in blank controls.A value in UVB + LBP group was significantly higher than that in UVB-irradiated group (P ＜ 0.05).SOD and CAT activity,and GSH-Px content in UVB-irradiated group were significantly lower (P ＜ 0.05) than that in the blank controls while the MDA content in UVB radiation group was significantly higher (P ＜ 0.05) than that in the blank controls.Moreover,in addition to dramatic reduction in MDA content,LBP treatment also significantly increased the activities of SOD and CAT,and GSH-Px content in UVB-irradiated cells (P ＜ 0.05).The expression levels of p38MAPK,caspase-8 and caspase-3 in UVB-irradiated group were higher than that in normal controls (P ＜ 0.05).In contrast,expression levels of Bcl-2 in UVB-irradiated group were lower than that in normal controls (P ＜ 0.05).The expression levels of p38MAPK,caspase-8 and caspase-3 were lower,and expression levels of Bcl-2 were higher in UVB + LBP group in comparison with UVB-irradiated group (P ＜ 0.05).Conclusion LBP can prevent UVB irradiation-induced the oxidative damage,up-regulation of expression levels of p38MAPK,caspase-8 and caspase3,and down-regulation of expression levels of Bcl-2 in HaCaT cells.