碘缺乏和碘过量对实验性甲状腺功能减退小鼠血脂代谢的影响

摘要

目的 观察碘缺乏和碘过量对实验性甲状腺功能减退(简称甲减)小鼠血脂代谢的影响,探讨碘不依赖于甲状腺激素的独立作用机制.方法 将雌性Balb/c小鼠按体质量随机分为6组:对照、重度低碘(SID)、轻度低碘(MID)、适碘(NI)、10倍碘过量(10HI)和50倍碘过量(50HI)组,每组10只.对照组饲以低碘饲料,其他各组饲以含0.2%甲基硫氧嘧啶的低碘饲料,同时饮用碘化钾(KI)配制的含碘量分别为326.79、0、196.08、326.79、3856.21、19 542.50 μg/L的去离子水.喂养3个月后,处死并收集小鼠外周血,分离血清.放射免疫分析法测定甲状腺激素水平,酶法检测血清中甘油三酯(TG)、总胆固醇(TC)、高密度脂蛋白胆固醇(HDL-C)及低密度脂蛋白胆固醇(LDL-C)水平.结果 ①SID[(21.27±9.63)μg/L]、MID[(23.41±3.93)μg/L]、NI[(22.57±4.66)μg/L]、10HI[(21.07±5.03)μg/L]和50HI组[(21.46±5.90)μg/L]血清TT4水平明显低于对照组[(42.15±8.26)μg/L,P均＜0.01],而各组间血清TT3水平比较,差异无统计学意义(F=0.99,P＞0.05).②10HI组TG水平[(1.17±0.16)mmol/L]与对照组[(1.39±0.22)mmol/L]和NI组[(1.51±0.22)mmol/L]比较,明显降低(P均＜0.05).50HI组TG和TC水平[(1.18±0.22)、(1.78±0.15)mmol/L]与对照组[(1.39±0.22)、(2.14±0.37)mmol/L]和NI组[(1.51±0.22)、(2.00±0.15)mmol/L]比较,明显降低(P均＜0.05).各组HDL-C、LDL-C水平比较,差异无统计学意义(F值分别为0.55、0.54,P均＞0.05).结论 碘可不依赖于甲状腺激素独立发挥调节甲减小鼠血脂的作用;监控碘的摄入量,对有效防治心血管疾病亦有重要作用.%Objective To observe the effects of iodine deficiency and iodine excess on the lipid metabolism in an experimental hypothyroid model of mice and to explore the roles of iodine independent of its role in thyroid hormones. Methods Female Balb/c mice were randomly divided into 6 groups: control, severe iodine deficiency (SID), mild iodine deficiency(MID), normal iodine (NI), 10-fold high iodine (10HI) and 50-fold high iodine(50HI), 10 in each group. The mice in control group were fed with low iodine forage, other mice were fed with low iodine forage containing 0.2% methylthiouracilum. All mice drank deionic water containing different concentrations of potassium iodide(KI). The iodine content in water was 326.79, 0, 196.08,326.79, 385621, 19 542.50 μg/L, respectively. After three months, thyroid hormones in the serum were determined by radioimmunoassay.Also, the blood samples were analyzed for total cholesterol (TC), triglyceride (TG), high density lipoprotein cholesteiol (HDL-C) and low density lipoprotein cholesterol (LDL-C) and measured enzymatically by automatic analyzer. Results ①The levels of Tr4 in SID[(21.27 ± 9.63)μg/L], MID[(23.41 ± 3.93)μg/L], NI[(22.57 ±4.66)μg/L], 10HI [(21.07 ± 5.03) μg/L] and 50HI groups [(21.46 ± 5.90) μg/L] were distinctively decreased compared with control group[(42.15 ± 8.26)μg/L, all P ＜ 0.01]. There were no statistical significant differences of rnTT3 between different groups (F = 0.99, P > 0.05 ). ②The level of TG in 10HI group [ ( 1.17 ± 0.16)mmol/L ] was obviously decreased compared with control [(1.39 ± 0.22 )mmol/L] and NI groups[(151 ± 0.22)mmol/L, all P＜ 0.05].Both TG and TC in 50HI group[(1.18 ± 0.22), (1.78 ± 0.15)mmol/L] were significantly decreased compared with control [( 1.39 ± 0.22), (2.14 ± 0.37)mmol/L] and NI groups [(1.51 ± 0.22), (2.00 ± 0.15)mmol/L, all P ＜ 0.05].The difference of serum HDL-C and LDL-C between the groups was not significant(F = 0.55,0.54, all P ＞ 0.05 ).Conclusions Dietary iodine plays a role in the metabolism of serum lipids independent of thyroid hormones.Thus, monitoring the amount of iodine intake during sodium restriction should also be taken extremely important for effectively prevention and cure of cardiovascular disease.