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International Journal of Pharmacology

Year: 2016  |  Volume: 12  |  Issue: 3  |  Page No.: 249 - 261

Inhibitory Effects of Thyroid Hormones on Mitochondrial Oxidative Stress: A Systematic Review

Mohammad Hadi Goharbari, Amir Shadboorestan and Mohammad Abdollahi

Abstract

Oxidative stress condition which is due to increased cellular free radicals has a main role in cell injury. Although free radicals are generated in normal metabolism, they may also be produced in excessive amounts during pathological conditions such as oxygen toxicity, drug overdose, chemical toxicity, ischemic-hypoxic injury and so on. The main parts of free radicals are Reactive Oxygen Species (ROS) which are mainly generated in cellular respiration. Increase in amount of ROS in pathological conditions can disturb mitochondrial function and make cellular damage. Thyroid hormones can act as a cytoprotective and antioxidant by inducing and activating some defense mechanisms against increased free radicals and mitochondrial oxidative stress. To review and categorize underlying mechanisms for the inhibitory effects of thyroid hormones on mitochondrial oxidative stress, Medline, Scopus and Web of science were searched for in vitro , in vivo, animal and human studies reporting antioxidant and cytoprotective effect of thyroid hormones in oxidative stress. After excluding duplicate, irrelevant and old articles the studies which had eligible criteria from 1980-2015 were included. Fifty one studies were included and evaluated in our study. It was found that thyroid hormones can induce cytoprotective and mitochondrial antioxidant effects through three mechanisms, consisting of increased activity and expression of uncoupling proteins, increased activity of mitoKATP channels, and increased activity and expression of antioxidant enzymes. Thyroid hormones have antioxidant effects through different mechanisms. More studies are needed to determine probable further mechanisms for thyroid hormones antioxidant effects and to confirm tissue hypothyroidism in oxidative stress.

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