Effects of high concentrations of iodide exposure on mitochondrial superoxide production in the thyroid of metallothionein Ⅰ/Ⅱ knockout mice / 中华地方病学杂志

ABSTRACT

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.