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目的 观察高碘对金属硫蛋白Ⅰ/Ⅱ敲除(MT-Ⅰ/Ⅱ KO)小鼠甲状腺线粒体超氧化物生成的影响.方法 利用6～8周龄健康雄性MT-Ⅰ/Ⅱ KO小鼠和同源对照(WT)小鼠的甲状腺组织,制备甲状腺细胞悬液,分别用10-4、10-3、10-2 mol/L碘化钾(KI)和10-3 mol/L过氧化氢(H2O2)处理2h,并以无KI或H2O2处理作为对照.利用甲基噻唑基四唑(MTT)法检测细胞活力,酶联免疫吸附试验(ELISA)法检测培养液中乳酸脱氢酶(LDH)含量,利用MitoSOX探针通过流式细胞术检测甲状腺细胞线粒体超氧化物生成.结果 与对照组[(100.00±0.00)％、(100.00±0.00)％]比较,10-4、10-3、10-2 mol/L KI组和10-3 mol/L H2O2组WT、MT-Ⅰ/Ⅱ KO小鼠甲状腺细胞活力[(73.63±2.05)％、(72.41±2.26)％、(69.63±2.29)％、(44.90±2.93)％和(65.40±2.39)％、(64.51±2.27)％、(61.48±2.33)％、(40.80±2.76)％]均显著下降(P均＜0.05),且MT-Ⅰ/Ⅱ KO小鼠与WT小鼠相比,细胞活力下降更加明显(P均＜0.05).与对照组[(1 995.28±30.52)、(2004.96±19.71)U/L]比较,10-4、10-3、10-2 mol/L KI组和10-3 mol/L H2O2组WT和MT-Ⅰ/Ⅱ KO小鼠甲状腺细胞培养液中LDH含量[(2 809.22±156.53)、(2 850.80±137.83)、(2 920.45±152.92)、(4 487.49±130.67)U/L和(3 261.06±120.44)、(3474.19±142.15)、(3 597.08±150.86)、(4 706.64±148.57)U/L]均显著升高(P均＜0.05),且MT-Ⅰ/Ⅱ KO小鼠与WT小鼠相比,LDH含量升高更加明显(P均＜0.05).与对照组(26.49±7.66、37.11±8.48)比较,10-2 mol/L KI组和10-3 mol/L H2O2组WT、MT-Ⅰ/ⅡKO小鼠甲状腺细胞线粒体超氧化物生成(58.96±5.11、87.95±4.25和71.21±5.55、99.76±4.42)明显增加(P均＜0.05);且MT-Ⅰ/Ⅱ KO小鼠与WT小鼠相比,线粒体超氧化物生成增加更加明显(P均＜ 0.05).结论 高碘(10-2 mol/L)和10-3 mol/L H2O2可诱导WT和MT-Ⅰ/Ⅱ KO小鼠甲状腺细胞线粒体超氧化物生成增多,细胞活力下降,LDH分泌增加;MT-Ⅰ/Ⅱ KO小鼠较WT小鼠甲状腺线粒体超氧化物生成增加更明显,提示MT-Ⅰ/Ⅱ在对抗氧化应激方面具有一定作用.“,”Objective To investigate the effects of high concentrations of iodide exposure on mitochondrial superoxide production,cell viability and cell damage in the thyroid of metallothionein Ⅰ/Ⅱ knockout (MT-Ⅰ/Ⅱ KO) mice and corresponding wild type (WT) mice.Methods Thyroid cell suspension of six to eight weeks old healthy male MT-Ⅰ/Ⅱ KO mice and WT mice were prepared.The thyroid cells were treated with high concentrations (10-4,10-3,10-2 mol/L) of potassium iodide(KI),or 10-3 mol/L hydrogen peroxide(H2O2) for 2 hours,respectively.Cell viability was evaluated with methyl thiazolyl tetrazolium(MTT) assay.Lactate dehydrogenase (LDH) level in cell culture medium was detected by enzyme-linked immunosorbent assay(ELISA).Mitochondrial superoxide production in the thyroid cells was measured by flow cytometry using a fluorescent probe,mitochondrial superoxide(MitoSOX).Results Compared to the control group[(100.00 ± 0.00)％,(100.00 ± 0.00)％],the cell viability of 10-4,10-3,10-2 mol/L KI and 10-3 mol/L H2O2 exposure groups were significantly decreased in the thyroid cells of both WT [(73.63 ± 2.05)％,(72.41 ± 2.26)％,(69.63 ± 2.29)％,(44.90 ± 2.93)％] and MT-Ⅰ/Ⅱ KO mice[(65.40 ± 2.39)％,(64.51 ± 2.27)％,(61.48 ± 2.33)％,(40.80 ± 2.76)％,all P＜ 0.05].Compared to the control group [(1 995.28 ± 30.52),(2 004.96 ± 19.71)U/L],significantly increased LDH activities were detected in the thyroid cells of WT [(2 809.22 ± 156.53),(2 850.80 ± 137.83),(2 920.45 ± 152.92),(4 487.49 ± 130.67)U/L] and MT-Ⅰ / Ⅱ KO mice [(3 261.06 ± 120.44),(3 474.19 ± 142.15),(3 597.08 ± 150.86),(4 706.64 ± 148.57)U/L,all P ＜ 0.05].Compared to the control group (26.49 ± 7.66,37.11 ± 8.48),the MitoSOX red fluorescence intensities of 10-2 mol/L KI and 10-3 mol/L H2O2 groups were significantly increased in WT mice(58.96 ± 5.11,87.95 ± 4.25) and MT-Ⅰ/ⅡKO mice(71.21 ± 5.55,99.76 ± 4.42) by flow cytometry (all P ＜ 0.05).Compared to the thyroid cells in WT mice,significantly decreased cell viability (all P ＜ 0.05),significantly increased LDH activity(all P ＜ 0.05) and significantly increased MitoSOX red fluorescence intensity by flow cytometry (all P ＜ 0.05) were detected in the thyroid cells of MT-Ⅰ/Ⅱ KO mice following treatment with KI or H2O2.Conclusions High concentrations of iodide (10-2 mol/L) and 10-3 mol/L H2O2 may lead to significant increase of mitochondrial superoxide production and LDH activity,decrease of cell viability in both WT and MT-Ⅰ / Ⅱ KO mice.More significant increase of superoxide production is detected in MT-Ⅰ / Ⅱ KO mice,indicating the potential protective role of metallothionein in the thyroid cells of WT mice.