Effects of iodine excess on mitochondrial superoxide production and mitochondrial membrane potential in rat thyroid cell line cells / 中国地方病学杂志

ABSTRACT

Objective To investigate the effects of iodine excess on mitochondrial superoxide production and mitoehondrial membrane potential(△ψ)changes in Fisher rat thyroid cell line(FRTL)cells.Methods FRTL cells were treated with 10-4mol/L potassium iodine(KI),10 U/L thyrotropin(TSH),10-4 mol/L KI+10 U/L TSH respectively for 24 h.Effects on cell proliferation were assayed by methyl thiazolyl tetrazolium(MTT)colorimetric method.Changes of mitochondrial superoxide production and △ψ were measured by live cell imaging and spectrofluorometer using MitoSOX and rhodamine 123(rh123)respectively.Results Absorbance(A)in the KI group (0.794±0.144)showed a significant decline compared to the control group(1.000 ±0.183,P<0.05),whereas a significant elevation was observed in the TSH group(1.215±0.156,P<0.05).No significant differences was found between the KI+TSH group(1.025±0.254)and the control group(P>0.05),but the former was marked higher than the KI group(P<0.05).Compared to the control group(9.74±3.24).MitoSOX mean fluorescence intensity (MFI)in the KI and KI+TSH groups(18.16±6.57,13.33±2.92)were significantly increased(all P<0.05),which was a significant decline in the TSH group(6.64±2.15,P<0.05).MitoSOX MFI in the KI+TSH group was lower than the KI group(P<0.05).Rh123 MFI in the KI and KI+TSH groups(210 593±31 328,295 525±34 243)showed significant decline than the control group(407 824±37 198,all P<0.05).Compared with the KI group.the KI+TSH group pronouncedly attenuated the reduction of Rh 123 MFI(P<0.05).No significant differences of Rh 123 MFI were found between the TSH group(411 187 ± 72 852) and the control group(P > 0.05). Conclusion Iodine excess (10-4 mol/L KI) may lead to peroxide damage on the mitochondria of FRTL cells, and cell proliferation is inhibited. Combining treatment with 10 U/L TSH may attenuate mitochondrial peroxide damage and inhibition of cell proliferation caused by iodine excess.