Franco Martha, Chávez Edmundo, Pérez-Méndez Oscar
Department of Nephrology, Instituto Nacional de Cardiología Ignacio Chávez, Juan Badiano 1, 14080 Mexico City, DF, Mexico.
J Thyroid Res. 2011;2011:321030. doi: 10.4061/2011/321030. Epub 2011 Jun 27.
Hypothyroidism induces several metabolic changes that allow understanding some physiopathological mechanisms. Under experimental hypothyroid conditions in rats, heart and kidney are protected against oxidative damage induced by ischemia reperfusion. An increased resistance to opening of the permeability transition pore seems to be at the basis of such protection. Moreover, glomerular filtration rate of hypothyroid kidney is low as a result of adenosine receptors-induced renal vasoconstriction. The vascular tone of aorta is also regulated by adenosine in hypothyroid conditions. In other context, thyroid hormones regulate lipoprotein metabolism. High plasma level of LDL cholesterol is a common feature in hypothyroidism, due to a low expression of the hepatic LDL receptor. In contrast, HDL-cholesterol plasma levels are variable in hypothyroidism; several proteins involved in HDL metabolism and structure are expressed at lower levels in experimental hypothyroidism. Based on the positive influence of thyroid hormones on lipoprotein metabolism, thyromimetic drugs are promising for the treatment of dyslipidemias. In summary, hypothyroid status has been useful to understand molecular mechanisms involved in ischemia reperfusion, regulation of vascular function and intravascular metabolism of lipoproteins.
甲状腺功能减退会引发多种代谢变化，有助于理解一些生理病理机制。在大鼠实验性甲状腺功能减退的情况下，心脏和肾脏可免受缺血再灌注诱导的氧化损伤。对通透性转换孔开放的抵抗力增加似乎是这种保护作用的基础。此外，由于腺苷受体诱导的肾血管收缩，甲状腺功能减退的肾脏的肾小球滤过率较低。在甲状腺功能减退的情况下，主动脉的血管张力也受腺苷调节。在其他情况下，甲状腺激素调节脂蛋白代谢。由于肝脏低密度脂蛋白受体表达较低，甲状腺功能减退时血浆低密度脂蛋白胆固醇水平较高是一个常见特征。相比之下，甲状腺功能减退时高密度脂蛋白胆固醇的血浆水平各不相同；在实验性甲状腺功能减退中，参与高密度脂蛋白代谢和结构的几种蛋白质表达水平较低。基于甲状腺激素对脂蛋白代谢的积极影响，拟甲状腺药物有望用于治疗血脂异常。总之，甲状腺功能减退状态有助于理解缺血再灌注、血管功能调节和脂蛋白血管内代谢所涉及的分子机制。
