维生素A对碘过量小鼠甲状腺细胞凋亡相关基因表达的影响

摘要

目的 观察维生素A对碘过量小鼠甲状腺细胞凋亡相关基因表达的影响.方法 将昆明种小鼠按体质量随机分成6组:对照(NI)组、高碘(HI)组、低维生素A(LVA)组、高碘低维生素A(HI+LVA)组、高碘补维生素A1(HI+VA1)组、高碘补维生素A2(HI+VA2)组.各组小鼠饲以合成饲料(维生素A分别为4000、4000、0、0、8000、16 000 U/kg),并饮用含不同剂量碘酸钾的去离子水(含碘量分别为50、3000、50、3000、3000、3000μg/L).分别在实验3、6个月时,采用原位末端标记(TUNEL)法检测甲状腺细胞凋亡水平,反转录-聚合酶链反应(RT-PCR)法检测甲状腺细胞凋亡相关基因Fas、FasL、Bcl-2 mRNA表达水平.结果甲状腺细胞凋亡指数随着月龄的增长呈逐渐上升的趋势.3个月时,HI组[(20.91±9.57)%]、HI+LVA组[(20.29±9.90)%]、HI+VA2组[(19.51±8.25)%]均明显高于NI组[(14.09±5.68)%,P均<0.05];6个月时,HI组[(23.22±8.58)%]、LVA组[(22.56±6.17)%]、HI+LVA组[(25.99±9.62)%]、HI+VA1组[(21.65±7.74)%]均明显高于Nl组[(16.80±9.90)%,P均<0.05].3、6个月时HI组Fas、FasL mRNA表达(Fas:1.57±0.36、1.49±0.35,FasL:1.85±0.46、1.84±0.32)与NI组(Fas:1.29±0.25、1.27±0.26,FagL:1.60±0.13、1.65±0.13)比较有增高趋势,但差异无统计学意义(P均>0.05);6个月时,HI+VA1、HI+VA2组Fas mRNA表达(1.33±0.35、1.30±0.26)与HI组比较有降低趋势,与NI组比较差异无统计学意义(P均>0.05);3、6个月时,HI+LVA组Fas、FagL mRNA表达(Fag:1.60±0.27、1.67±0.32,FagL:1.88±0.46、2.10±0.34)与HI组比较,差异均无统计学意义(P均>0.05).上述各组Bcl-2 mRNA表达水平3个月时分别为1.05±0.19、0.96±0.33、0.95±0.26、1.18±0.27、1.10±0.19、0.98±0.36,6个月时分别为1.35±0.28、1.60±0.25、1.48±0.18、1.71±0.26、1.66±0.29、1.56±0.35,组间比较差异均无统计学意义(P均>0.05).结论 高碘可引起小鼠甲状腺细胞凋亡;补充VA在一定程度上调控了凋亡相关基因的表达水平,部分拮抗了高碘引起的细胞凋亡.%Objective To explore the effects of different vitamin A(VA) levels on thyroid cells apoptosis and its gene expression of mice taking excessive iodine. Methods Kunming mice were randomly divided into 6 groups according to body weight 3 weeks after born: normal control(NI) group, high iodine(HI) group, low vitamin (LVA) group, high iodine plus low vitamin A(HI+LVA) group, high iodine plus vitamin A1 (HI+VA1) group, high iodine plus vitamin A2(HI+VA2) group. The VA was given in food(4000,4000,0,0,8000,16 000 U/kg), and the iodine was given as potassium iodate in water (I-:50,3000,50,3000,3000,3000 μg/L). The apoptosis was tested using in situ end labehng(TUNEL) method. Reverse transcription polymerase chain reaction (RT-PCR) were used to measure the level of mRNA of apoptosis gene(Fas, FasL, Bcl-2) in tissues. Results Apoptotic index measured by TUNEL method was rising along with the mice age. Compared to NI group[(14.09±5.68)%], apoptotic index was significantly increased in HI[(20.91±9.57)%], HI+LVA[(20.29±9.90)%]and HI+VA2 [(19.51±8.25)%]groups in the three months(P < 0.05). Compared to NI group[(16.80±9.90)%], apoptotic index was significantly increased(P < 0.05) in HI[(23.22±8.58)%],LVA[(22.56±6.17)%],HI+LVA [(25.99±9.62)%],HI+VA1 [(21.65±7.74)%]groups in the six months. Compared with the NI group(Fas: 1.29±0.25,1.27±0.26; FasL: 1.60±0.13,1.65±0.13), the mRNA levels of Fas and FasL in HI group(Fas: 1.57±0.36,1.49±0.35; FasL: 1.85±0.46,1.84±0.32) were increased, but the differences were not remarkable(P > 0.05) in the three and six months. Compared with the HI group, the mRNA levels of Fas in HI+ VA1, HI+VA2(1.33±0.35, 1.30±0.26) groups were decreased to the level in NI group in the six months. The mRNA levels of Fas and FasL were not different (P > 0.05) between HI+LVA(I.60±0.27,1.88±0.46) and HI groups in the three months. The mRNA levels of Bcl-2 were not remarkably differences in the three months (1.05±0.19,0.96±0.33,0.95±0.26,1.18±0.27,1.10±0.19,0.98±0.36, all P > 0.05), and in the six months (1.35±0.28,1.60±0.25,1.48±0.18,1.71±0.26,1.66±0.29,1.56±0.35, all P > 0.05). Conclusions Excessive iodine can cause thyroid cells apoptosis in mice. Supplementation of suitable amount of VA can regulate the levels of the apoptosis-related genes expression, and partly antagonize the apoptosis caused by high iodine.