短期铁缺乏对大鼠甲状腺功能的影响

目的 研究短期铁缺乏对大鼠甲状腺功能的影响,并探讨其机制,为碘缺乏病的防治工作提供新的线索和思路.方法 选择健康SPF/VAF级初断乳SD雄性大鼠22只,按体质量随机分为对照组(饲料含铁量为65 mg/kg)和铁缺乏组(饲料含铁量为15 mg/kg),每组11只.喂养4周后,测定大鼠体质量和甲状腺质量,并计算甲状腺相对质量.取大鼠全血并分离血清,采用生化法检测血红蛋白、血清铁水平和总铁结合力;化学发光法检测血清游离三碘甲腺原氨酸(FT3)、游离甲状腺素(FT4)和促甲状腺激素(TSH)水平.甲状腺常规固定包埋切片后,免疫组化染色观察甲状腺过氧化物酶(TPO)蛋白表达情况.结果 铁缺乏组大鼠体质量[(214.3±18.1)g]比对照组[(243.8±16.4)g]减轻(t=4.002,P＜0.01),甲状腺绝对质量[(11.9±1.6)mg]比对照组[(13.4±1.3)mg]降低(t=2.369,P＜0.01),但甲状腺相对质量[(0.055±0.004)g/kg]与对照组[(0.055±0.006)g/kg]比较未见明显变化(t=0.162,P＞0.05).铁缺乏组大鼠血红蛋白水平[(100.4±8.9)g/L]和血清铁水平[(7.0±0.8)μmol/L]比对照组[(146.5±16.3)g/L、(26.1±5.1)μmol/L]降低(t值分别为8.233、12.277,P均＜0.01),总铁结合力[(124.8±6.3)μmol/L]比对照组[(74.0±4.6)μmol/L]升高(t=21.531,P＜0.01).铁缺乏组大鼠血清FT3、FT4和FT3/FT4[(4.71±0.53)、(29.69±2.63)pmol/L、0.16±0.02]均较对照组[(5.69±0.61)、(31.98±2.49)pmol/L、0.18±0.01]降低(t值分别为4.044、2.096、3.255,P＜0.01或＜0.05).铁缺乏组大鼠TPO蛋白表达强度较对照组减弱.结论 铁缺乏可导致甲状腺功能低下,可能与铁缺乏状态下TPO活性降低有关,碘铁联合补充可能会改善铁缺乏地区碘缺乏病防治的效果.

Abstract：

Objective To explore the effect of short-term iron deficiency on thyroid function of rat and its mechanism, and to provide new clues and ideas for prevention and control of iodine deficiency disorders. Methods Twenty-two healthy SPF/VAF level weaning male SD rats were randomly divided into control group(iron content in diet was 65 mg/kg) and iron deficiency group(iron content in diet was 15 mg/kg) by body weight, and 11 in each group respectively. After 4 weeks feeding, body weight and thyroid glands weight were measured, and the relative weight of thyroid gland was calculated. Rat whole blood was collected and serum was separated. Hemoglobin, serum iron levels and total iron binding capacity were tested using biochemical assay;serum free iodine thyroid three original acid (FT3), free thyroxine (FT4) and thyroid stimulating hormone (TSH) levels were detected by chemiluminescence;after thyroid were fixed in formalin, embedded with paraffin and sectioned regularly, and immunohistochemical stained, the protein expression of thyroid peroxidase(TPO) was observed. Results Compared with control group [(243.8 ± 16.4)g], iron deficiency group of animals had less body weight[(214.3 ± 18.1 )g, t = 4.002, P ＜ 0.01];there was a lower absolute thyroid weight in iron deficiency group[(11.9 ± 1.6)mg]than in control group[(13.4 ±1.3)mg, t = 2.369, P ＜ 0.01], but no significant changes of the relative weight of thyroid gland between the two groups[(0.055 ± 0.004),(0.055 ± 0.006)g/kg, t = 0.162, P ＞ 0.05]. Hemoglobin and serum iron in iron deficiency group were ( 100.4 ± 8.9)g/L and (7.0 ± 0.8)μmol/L, which were less than that in control group[( 146.5 ±16.3)g/L, (26.1 ± 5.1 )μmol/L, t = 8.233,12.277, all P ＜ 0.01]. Total iron binding capacity in control group was (74.0 ± 4.6)μ mol/L and that in iron deficiency group[(124.8 ± 6.3)μmol/L], and the difference was significant (t = 21.531, P＜ 0.01). At the same time, their serum hormones FT3, FT4 and FT3/FT4[(4.71 ± 0.53), (29.69 ±2.63)pmol/L, 0.16 ± 0.02]were lower than that in control group[(5.69 ± 0.61),(31.98 ± 2.49)pmol/L, 0.18 ±0.01, t = 4.044,2.096,3.255, P ＜ 0.01 or ＜ 0.05]. The expression of TPO protein decreased in iron deficiency group than in control group. Conclusions Iron deficiency reduces thyroid function, which perhaps is due to the reduction of TPO activity. Combined supplementation of iodine and iron will possibly improve the prevention effect on iodine deficiency disorder in iron deficiency areas.

Short-term iron deficiency on rat thyroid function

Objective To explore the effect of short-term iron deficiency on thyroid function of rat and its mechanism, and to provide new clues and ideas for prevention and control of iodine deficiency disorders. Methods Twenty-two healthy SPF/VAF level weaning male SD rats were randomly divided into control group(iron content in diet was 65 mg/kg) and iron deficiency group(iron content in diet was 15 mg/kg) by body weight, and 11 in each group respectively. After 4 weeks feeding, body weight and thyroid glands weight were measured, and the relative weight of thyroid gland was calculated. Rat whole blood was collected and serum was separated. Hemoglobin, serum iron levels and total iron binding capacity were tested using biochemical assay;serum free iodine thyroid three original acid (FT3), free thyroxine (FT4) and thyroid stimulating hormone (TSH) levels were detected by chemiluminescence;after thyroid were fixed in formalin, embedded with paraffin and sectioned regularly, and immunohistochemical stained, the protein expression of thyroid peroxidase(TPO) was observed. Results Compared with control group [(243.8 ± 16.4)g], iron deficiency group of animals had less body weight[(214.3 ± 18.1 )g, t = 4.002, P ＜ 0.01];there was a lower absolute thyroid weight in iron deficiency group[(11.9 ± 1.6)mg]than in control group[(13.4 ±1.3)mg, t = 2.369, P ＜ 0.01], but no significant changes of the relative weight of thyroid gland between the two groups[(0.055 ± 0.004),(0.055 ± 0.006)g/kg, t = 0.162, P ＞ 0.05]. Hemoglobin and serum iron in iron deficiency group were ( 100.4 ± 8.9)g/L and (7.0 ± 0.8)μmol/L, which were less than that in control group[( 146.5 ±16.3)g/L, (26.1 ± 5.1 )μmol/L, t = 8.233,12.277, all P ＜ 0.01]. Total iron binding capacity in control group was (74.0 ± 4.6)μ mol/L and that in iron deficiency group[(124.8 ± 6.3)μmol/L], and the difference was significant (t = 21.531, P＜ 0.01). At the same time, their serum hormones FT3, FT4 and FT3/FT4[(4.71 ± 0.53), (29.69 ±2.63)pmol/L, 0.16 ± 0.02]were lower than that in control group[(5.69 ± 0.61),(31.98 ± 2.49)pmol/L, 0.18 ±0.01, t = 4.044,2.096,3.255, P ＜ 0.01 or ＜ 0.05]. The expression of TPO protein decreased in iron deficiency group than in control group. Conclusions Iron deficiency reduces thyroid function, which perhaps is due to the reduction of TPO activity. Combined supplementation of iodine and iron will possibly improve the prevention effect on iodine deficiency disorder in iron deficiency areas.