Short-term iron deficiency on rat thyroid function / 中国地方病学杂志

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.