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目的:探讨左旋甲状腺素对甲状腺功能减退症模型大鼠神经系统的保护作用。方法:取大鼠随机分为正常对照组、模型组和药物组,除正常对照组灌胃给予三蒸水外,其余2组连续灌胃给予丙基硫氧嘧啶(PTU)8周建立甲状腺功能减退症模型。8周后模型组再分为模型A组(继续给予PTU)和模型B组(停止给予PTU);药物组灌胃给予左旋甲状腺素钠60μg.kg-1,连续4周。检测首次建模给药后第3、6、8、10、12周各组大鼠(n=6)血清中促甲状腺素(TSH)、游离三碘甲状腺原氨酸(FT3)、游离甲状腺素(FT4)水平与海马组织中即早基因c-fos、c-jun表达,并在末次给药后电镜观察各组海马组织病理学变化。结果:与正常对照组比较,模型组和药物组大鼠3、6、8周FT3和FT4水平均明显降低(P<0.01),且随病程延长呈递减趋势,TSH、c-fos、c-jun表达均明显升高(P<0.05或P<0.01)。与模型A、B组比较,药物组大鼠10、12周FT3和FT4水平均明显升高(P<0.05),TSH、c-fos、c-jun表达均明显降低(P<0.05)。药物组与正常对照组同期相比无明显差异(P>0.05)。与模型A组比较,模型B组10、12周FT3和FT4水平均明显升高(P<0.05),c-fos、c-jun表达均明显降低(P<0.05),12周TSH水平明显降低(P<0.05)。电镜观察发现甲状腺功能减退症状严重程度模型A组>模型B组>药物组。结论:左旋甲状腺素钠可以减轻甲状腺功能减退症模型大鼠神经系统症状,可能与抑制c-fos、c-jun表达有关。
Objective: To investigate the protective effect of levothyroxine on the nervous system of hypothyroidism model rats. Methods: The rats were randomly divided into normal control group, model group and drug group. Except for the normal control group, three distilled water was given intragastrically. The other two groups were given continuous intragastric administration of propylthiouracil (PTU) for 8 weeks to establish thyroid function Alzheimer’s disease model. After 8 weeks, the model group was further divided into model group A (PTU continued) and model group B (PTU stopped). The drug group was given 60μg.kg-1 sodium levothyroxine for 4 weeks. The levels of thyroid-stimulating hormone (TSH), free triiodothyronine (FT3) and free thyroxine in serum of rats in each group (n = 6) (FT4) and hippocampus early genes c-fos, c-jun expression, and in the last administration after electron microscopy, histopathological changes in each group hippocampus. Results: Compared with the normal control group, the levels of FT3 and FT4 in the model group and the drug group were significantly decreased at 3, 6, and 8 weeks (P <0.01), and decreased with the prolongation of the duration. The levels of TSH, c-fos, jun expression were significantly increased (P <0.05 or P <0.01). Compared with model group A and group B, the levels of FT3 and FT4 were significantly increased (P <0.05) and the expressions of TSH, c-fos and c-jun in the drug group were significantly decreased at 10 and 12 weeks (P <0.05). Drug group and the normal control group compared to the same period no significant difference (P> 0.05). Compared with model group A, the levels of FT3 and FT4 in model group B at 10 and 12 weeks were significantly increased (P <0.05), and the expressions of c-fos and c-jun were significantly decreased (P <0.05) (P <0.05). Electron microscopy found that the severity of hypothyroidism symptoms model group A> model B group> drug group. Conclusion: L-thyroxine can relieve the neurological symptoms of hypothyroidism model rats, which may be related to the inhibition of the expression of c-fos and c-jun.