Videla Luis A, Fernández Virginia, Cornejo Pamela, Vargas Romina, Morales Paula, Ceballo Juan, Fischer Alvaro, Escudero Nicolás, Escobar Oscar
Luis A Videla, Virginia Fernández, Pamela Cornejo, Romina Vargas, Paula Morales, Juan Ceballo, Alvaro Fischer, Nicolás Escudero, Oscar Escobar, Molecular and Clinical Pharmacology Program, Institute of Biomedical Sciences, Faculty of Medicine, University of Chile, Independencia 1027, Santiago, Chile.
World J Gastroenterol. 2014 Dec 14;20(46):17416-25. doi: 10.3748/wjg.v20.i46.17416.
To investigate the redox dependency and promotion of downstream targets in thyroid hormone (T3)-induced AMP-activated protein kinase (AMPK) signaling as cellular energy sensor to limit metabolic stresses in the liver.
Fed male Sprague-Dawley rats were given a single ip dose of 0.1 mg T3/kg or T3 vehicle (NaOH 0.1 N; controls) and studied at 8 or 24 h after treatment. Separate groups of animals received 500 mg N-acetylcysteine (NAC)/kg or saline ip 30 min prior T3. Measurements included plasma and liver 8-isoprostane and serum β-hydroxybutyrate levels (ELISA), hepatic levels of mRNAs (qPCR), proteins (Western blot), and phosphorylated AMPK (ELISA).
T3 upregulates AMPK signaling, including the upstream kinases Ca(2+)-calmodulin-dependent protein kinase kinase-β and transforming growth factor-β-activated kinase-1, with T3-induced reactive oxygen species having a causal role due to its suppression by pretreatment with the antioxidant NAC. Accordingly, AMPK targets acetyl-CoA carboxylase and cyclic AMP response element binding protein are phosphorylated, with the concomitant carnitine palmitoyltransferase-1α (CPT-1α) activation and higher expression of peroxisome proliferator-activated receptor-γ co-activator-1α and that of the fatty acid oxidation (FAO)-related enzymes CPT-1α, acyl-CoA oxidase 1, and acyl-CoA thioesterase 2. Under these conditions, T3 induced a significant increase in the serum levels of β-hydroxybutyrate, a surrogate marker for hepatic FAO.
T3 administration activates liver AMPK signaling in a redox-dependent manner, leading to FAO enhancement as evidenced by the consequent ketogenic response, which may constitute a key molecular mechanism regulating energy dynamics to support T3 preconditioning against ischemia-reperfusion injury.
研究甲状腺激素（T3）诱导的AMP活化蛋白激酶（AMPK）信号传导中作为细胞能量传感器的氧化还原依赖性及其对下游靶点的促进作用，以限制肝脏中的代谢应激。
给喂食的雄性Sprague-Dawley大鼠腹腔注射单次剂量为0.1 mg T3/kg或T3溶媒（0.1 N NaOH；对照组），并在治疗后8或24小时进行研究。另一组动物在T3给药前30分钟腹腔注射500 mg N-乙酰半胱氨酸（NAC）/kg或生理盐水。测量指标包括血浆和肝脏8-异前列腺素水平、血清β-羟基丁酸水平（酶联免疫吸附测定法）、肝脏mRNA水平（定量聚合酶链反应）、蛋白质水平（蛋白质免疫印迹法）以及磷酸化AMPK水平（酶联免疫吸附测定法）。
T3上调AMPK信号传导，包括上游激酶钙调蛋白依赖性蛋白激酶激酶-β和转化生长因子-β激活激酶-1，T3诱导的活性氧发挥了因果作用，因为抗氧化剂NAC预处理可抑制其产生。相应地，AMPK的靶点乙酰辅酶A羧化酶和环磷酸腺苷反应元件结合蛋白被磷酸化，同时肉碱棕榈酰转移酶-1α（CPT-1α）被激活，过氧化物酶体增殖物激活受体-γ共激活因子-1α以及脂肪酸氧化（FAO）相关酶CPT-1α、酰基辅酶A氧化酶1和酰基辅酶A硫酯酶2的表达增加。在这些条件下，T3导致血清β-羟基丁酸水平显著升高，β-羟基丁酸是肝脏FAO的替代标志物。
T3给药以氧化还原依赖性方式激活肝脏AMPK信号传导，导致FAO增强，随后的生酮反应证明了这一点，这可能构成调节能量动态以支持T3预处理抵抗缺血再灌注损伤的关键分子机制。
