They further suggested that exercise resulted in increase in irisin levels by increasing fibronectin type III domain-containing protein 5(FNDC5) gene expression thereby relieving oxidative stress.18,28 Effect of r- irisin on tissue oxidative stress and aortic tissue endothelial dysfunction was evaluated by Sarwar M et al., and they established that exogenous irisin ameliorates nicotine-induced oxidative stress and vascular dysfunction by improving antioxidant enzymes’ levels with corresponding decrease in membrane lipid peroxidation and severity of aortic tissue damage.29 Here, FNDC5 is linked to endothelial dysfunction.