FNDC5 and ischemia: In peri-infarct brain tissue, the rising levels of superoxide anion, nitrotyrosine, and 4-hydroxy-2-nonenals (4-HNEs) cause ischemia-induced neuronal injury, in which irisin exerts antioxidative and neuroprotective effects by activating protein kinase B (PKB) and extracellular-regulated protein kinase (ERK) pathways [97].