摘要目的 探讨长期低硒、低蛋白质和低维生素E(VE)膳食对大鼠甲状腺组织及其激素代谢的影响.方法 Wistar大鼠40只,按体质量随机分为4组:低硒低蛋白低VE组、低硒低蛋白常VE组、常硒常蛋白低VE组、常硒常蛋白常VE组.饲养至第26周处死,测定大鼠全血谷胱甘肽过氧化物酶(GSH-Px)和肝脏Ⅰ型5'-脱碘酶(ID Ⅰ)活性,血清活性氧(ROS)、丙二醛(MDA)、三碘甲状腺原氨酸(T3)、四碘甲状腺原氨酸(T4)和促甲状腺激素(TSH)水平;光镜下观察甲状腺组织病理学改变.结果 ①硒+蛋白质和vE对大鼠全血GSH-Px和肝脏ID Ⅰ活性的影响均无交互作用(F值分别为0.003、0.871,P＞0.05),但对血清MDA和ROS水平的影响均存在交互作用(F值分别为13.057、6.706,P＜0.05或＜0.01).②硒+蛋白质和VE对血清T3、T4水平均有影响(F值分别为431.977、28.271、6.570、41.419,P＜0.05).但均无交互作用(F值分别为0.871、0.136,P＞0.05).无论在低硒低蛋白还是常硒常蛋白条件下,常VE组T4水平[(79.095±12.199)、(64.392±6.261)μg/L]均高于低VE组[(61.068±6.648)、(44.176±7.090)μg/L],差异有统计学意义(t值分别为3.670、6.045,P＜0.01);在低VE条件下,常硒常蛋白组T3、T4水平[(0.718±0.079)、(44.176±7.090)μg/L]均低于低硒低蛋白组[(0.966±0.156)、(61.068±6.648)μg/L],差异有统计学意义(t值分别为4.568、4.916,P＜0.01);在常VE条件下,常硒常蛋白组Td水平[(64.392±6.261)μg/L]低于低硒低蛋白组[(79.095±12.199)μg/L],差异有统计学意义(t=3.033,P＜0.01).③低硒低蛋白低VE膳食大鼠甲状腺滤泡上皮细胞出现变性坏死,而补充VE可减轻这种损伤:常硒常蛋白低VE膳食大鼠偶见滤泡腔内胶质稀疏.结论 长期低硒、低蛋白、低VE膳食可导致大鼠体内含硒酶活性降低,从而引起机体氧化代谢产物堆积,甲状腺组织出现病理性损伤,其激素代谢紊乱,而在低硒、低蛋白膳食中补充适量VE可部分降低这种损伤现象.

abstractsObjective To explore the effect of associated deficiency of selenium,protein and vitamin E(VE)on the thyroid iniury and thyroid hormone metabolism of the rats in a long-term.Methods The Wistar rats were randomly divided into four groups:Group A with selenium deficiency and low protein and VE;Group B with selenium deficiency,low protein but adequate VE;Group C,adequate selenium and protein but low VE;Group D,adequate selenium.protein and VE.The rats were killed at the end of 26th week.Glutathione peroxidase(GSH-Px)activity in the rat blood and type I 5'-deiodinase activity of the rat liver were determined.The content of triiodothyronine(T3),tetraiodothyronine(T4),thyrotropic-stimulating hormone(TSH),activated oxygen(ROS)and malonaldehyde(MDA)were detected in serum. The changes of thyroid histopathology were observed under light microscope.Results ①The interactive effect of selenium+protein and VE was not significant on GSH-Px and ID I activity(F=0.003,0.871,P＞0.05),but it was significant on MDA and ROS content(F=13.057,6.706,P＜0.05 or＜0.01). ②Selenium+protein and VE could influence T3 and T4 content(F=431.977,28.271,6.570,41.419,P＜0.05).The interactive effect of selenium±protein and VE was not significant on T3 and T4 content(F=0.871,0.136,P＞0.05).Whether in the condition of low selenium and protein or supplementary,T4 contents of supplementary VE group[(79.095±12.199),(64.392±6.261)μg/L]were respectively higher than the low VE group[(61.068±6.648),(44.176±7.090)μg/L],the difference being statistically significant(t = 3.670,6.045, P ＜ 0.01). In the condition of low VE, T3[(0.718 ± 0.079)μg/L] and T4[(44.176 ±7.090)μg/L] content of supplementary selenium and protein group was lower than that in the low selenium and protein group[ (0.966 ± 0.156), (61.068 ± 6.648)μg/L], the difference being statistically significant (t = 4.568,4.916, P ＜0.01 ). With supplementary VE, T4 content of supplementary selenium and protein group[ (64.392 ± 6.261 )μg/L] was lower than that in the low selenium and protein group [(79.095 ± 12.199)μg/L], the difference being statistically significant (t = 3.033, P ＜ 0.01 ). ③Degeneration and necrosis of follicular epithelial cell were induced by diet of low selenium, protein and VE, which could be relieved by supplymentary VE. The sparseness of intracavitary glue was observed occationally in the supplementary selenium and protein but low VE group. Conclusions Long-term deficiency of selenium, protein and VE results in the decrease of the selenoenzymes of rats, which causes accumulation of the oxidative products, as well as thyroid pathological injury and thyroid hormone metabolism disorder, but supplement of adequate VE can reduce the oxidative damage in rats having low selenium and protein diet.