摘要目的 研究L-3,5-二碘酪氨酸(DIT)和碘酸钾(KIO3)对缺碘大鼠的补碘效果.方法 取60只体质量为160～ 180 g的Wistar大鼠,按体质量采用随机数字表法分为缺碘模型组和适碘模型组.缺碘模型组大鼠40只,饲以低碘饲料(碘含量为35.9 μg/kg);适碘模型组大鼠20只,饲以低碘饲料的同时每天灌胃含KIO3(碘含量为18 mg/L)水0.5 ml.模型建立时间为3个月.缺碘模型组大鼠再分为3组:低碘(LI)组(8只)、KIO3组(9只)、DIT组(10只);适碘模型组取9只大鼠作为适碘对照(NI)组.LI组饲以低碘饲料;KIO3组饲以低碘饲料的同时每天灌胃含KIO3(碘含量为18 mg/L)水0.5ml;DIT组饲以低碘饲料的同时每天灌胃含DIT(碘含量为18 mg/L)水0.5 ml;NI组饲以低碘饲料的同时每天灌胃含KIO3(碘含量为18 mg/L)水0.5 ml.3个月后,收集各组大鼠24 h尿样,尿中碘的砷铈催化分光光度法(WS/T 107-2006)检测尿碘;25％乌拉坦腹腔注射麻醉大鼠,腹主动脉采血,全自动电化学发光免疫分析法测定大鼠血清甲状腺激素[三碘甲状腺原氨酸(TT3)、游离三碘甲状腺原氨酸(FT3)、甲状腺素(TT4)、游离甲状腺素((FT4)]水平;处死大鼠,称量甲状腺重量.结果 ①4组大鼠尿碘含量比较差异有统计学意义(x2=25.24,P＜0.05),其中LI组尿碘中位数明显低于NI、KIO3和DIT组(3.00比286.14、223.37、214.33 μg/L,P均＜0.05).②4组大鼠血清TT3 、TT4、FT3、FT4含量比较差异有统计学意义(F=63.48、140.73、130.20、365.27,P均＜0.05),其中KIO3组大鼠各激素水平低于DIT组[TT3:(1.57±0.20)比(1.97±0.18) mmol/L、TT4:(51.23±4.90)比(71.94±5.27)mmol/L、FT3:(5.34±0.45)比(6.98±0.33)pmol/L、FT4:(26.18±2.30)比(35.47±2.28) pmol/L,P均＜0.05].③KIO3和DIT组大鼠甲状腺均呈淡粉色;4组大鼠甲状腺绝对重量、相对重量比较差异均有统计学意义(F=225.05、345.40,P均＜0.05),其中DIT组大鼠甲状腺绝对重量[(31.76±1.75)mg]和相对重量[(11.69±3.47)mg/100 g]均低于KIO3组[(36.31±5.23)mg、(12.83±4.38)mg/100 g,P均＜0.05].结论 动物实验结果显示DIT的补碘效果优于KIO3.

abstractsObjective To study the efficacy of L-3,5-diiodotyrosine (DIT) and inorganic iodine (KIO3) in iodine-deficiency Wistar rats.Methods Sixty Wistar rats,weighting about 160-180 g,were divided into two groups according to body weight by the random number table method:iodine-deficiency model (40 rats) was fed with low-iodine food (the iodine content was 35.9 μg/kg);optimal-iodine model (20 rats) was fed with low-iodine food and given with KIO3 water (the iodine content was 18 mg/L) 0.5 ml by intragastric once a day.Model was established for 3 months.Iodine-deficiency model was subdivided into low iodine (LI) group,KIO3 group and DIT group,eight,nine,ten rats in each group;from optimal-iodine model,nine rats were randomly selected as optimal iodine (NI) group.LI group was fed with low-iodine food;KIO3 group was fed with low-iodine food and given with KIO3 water (the iodine content was 18 mg/L) 0.5 ml by intragastric once a day;DIT group was fed with low-iodine food and given with DIT water (the iodine content was 18 mg/L) 0.5 ml by intragastric once a day;NI group was fed with low-iodine food and given with KIO3 water (the iodine content was 18 mg/L) 0.5 ml by intragastric once a day.After 3 months,24-hour urine of the rats was collected.According to the method for determination of iodine in urine by As3 +-Ce4+ catalytic spectrophotometry (WS/T 107-2006),iodine content in urine was detected.Rats were anesthetized intraperitoneally with 25％ urethane,blood from abdominal aortic was collected to determinate the serum thyroid hormone [total triiodothyronine (TT3),total thyroxine (TT4),free triiodothyronine (FT3),free thyroxine (FT4)] level in rats by automatic electrochemical luminescence immunoassay.All the rats were sacrificed to analyze the thyroid weight.Results ① The urine iodine showed significant differences in the four groups (x2 =25.24,P ＜ 0.05).The median of urine iodine concentration in the LI,NI,KIO3 and DIT groups were 3.00,286.14,223.37,214.33 μg/L,respectively.The urine iodine concentration in LI group was significantly lower than those of other three groups (all P ＜ 0.05).② The serum TT3,TT4,FT3,FT4 levels showed significant differences in the four groups (F =63.48,140.73,130.20,365.27,all P ＜ 0.05).And the hormone levels in KIO3 group were lower than those of the DIT group [TT3:(1.57 ± 0.20) vs.(1.97 ± 0.18) mmol/L,TT4:(51.23 ± 4.90) vs.(71.94 ± 5.27) mmol/L,FT3:(5.34 ± 0.45) vs.(6.98 ± 0.33) pmol/L,FT4:(26.18 ± 2.30) vs.(35.47 ± 2.28) pmol/L,all P ＜ 0.05].③The color of thyroid in KIO3 and DIT groups became pale pink.The absolute and relative thyroid weight showed significant differences in the four groups (F =225.05,345.40,all P ＜ 0.05).The absolute thyroid weight [(31.76 ± 1.75) mg] and relative thyroid weight [(11.69 ± 3.47) mg/100 g] in DIT group was lower than that of the KIO3 group [(36.31 ± 5.23) mg,(12.83 ± 4.38) mg/100 g,all P ＜ 0.05].Conclusion Animal experimental results show that DIT has a better iodine-supplementing efficacy than that of KIO3.