BACKGROUND In this study, the effect of levothyroxine (L-T4) on tracheal responsiveness, lung inflammation, oxidative stress and pathological features in a rat model of Alzheimer's disease (AD), was evaluated. METHODS An animal model of AD was established by intracerebroventricular injection of streptozotocin (STZ) (3 mg/kg) in rats. The rats were then treated for 3 weeks with L-T4 (10 and 100 μg/kg). RESULTS In AD animals, tracheal responsiveness to methacholine and ovalbumin (p < 0.05), white blood cell (WBC) count (p < 0.05 to p < 0.01), malondialdehyde (MDA) concentration (p < 0.05) and inflammation score (p < 0.01) were increased, but superoxide dismutase (SOD) activity and total thiol content (for both cases p < 0.05) were decreased compared to the controls. Tracheal responsiveness to methacholine and MDA concentration (p < 0.05) were decreased in AD animals treated with T4 compared to the AD group. Bronchial inflammation in terms of total and some differential WBC in the BALF and inflammatory score, was significantly worsened in AD animals treated with high dose of T4 (p < 0.05 to p < 0.001) compared to the controls. CONCLUSION Alzheimer's disease may cause lung inflammation and treatment with low dose of T4 improved MDA level and lung inflammation.

中文翻译：

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左旋甲状腺素对阿尔茨海默病大鼠模型肺部炎症、氧化应激和病理学的影响。

背景在本研究中，评估了左旋甲状腺素 (L-T4) 对阿尔茨海默病 (AD) 大鼠模型气管反应性、肺部炎症、氧化应激和病理特征的影响。方法通过脑室内注射链脲佐菌素（STZ）（3 mg/kg）建立AD动物模型。然后用 L-T4（10 和 100 μg/kg）处理大鼠 3 周。结果在 AD 动物中，气管对乙酰甲胆碱和卵清蛋白的反应性 (p < 0.05)、白细胞 (WBC) 计数（p < 0.05 至 p < 0.01）、丙二醛 (MDA) 浓度（p < 0.05）和炎症评分（p < 0.05） 0.01) 增加，但与对照相比，超氧化物歧化酶 (SOD) 活性和总硫醇含量（对于这两种情况，p < 0.05）降低。与 AD 组相比，用 T4 治疗的 AD 动物对乙酰甲胆碱和 MDA 浓度的气管反应性（p < 0.05）降低。与对照组相比，用高剂量 T4 治疗的 AD 动物（p < 0.05 至 p < 0.001）中的支气管炎症在 BALF 和炎症评分中的总和一些差异 WBC 中显着恶化。结论阿尔茨海默病可能引起肺部炎症，低剂量T4治疗可改善MDA水平和肺部炎症。