Fibroblast growth factor 19 (FGF19) has emerged as a crucial cytoprotective regulator that antagonizes cell apoptosis and oxidative stress under adverse conditions. However, whether FGF19 plays a cytoprotective role in preventing myocardial damage during myocardial ischemia/reperfusion injury remains unknown. In this study, we aimed to investigate the potential role of FGF19 in regulating hypoxia/reoxygenation (H/R)-induced injury of cardiomyocytes in vitro. We found that FGF19 expression was upregulated in response to H/R treatment in cardiomyocytes. Silencing of FGF19 significantly inhibited viability and increased apoptosis and reactive oxygen species (ROS) generation in cardiomyocytes with H/R treatment. In contrast, overexpression of FGF19 improved viability and inhibited apoptosis and ROS generation induced by Hilt treatment, showing a cardioprotective effect. Moreover, we found that FGF19 regulated the phosphorylation of glycogen synthase kinase-3 beta (GSK-3 beta) and the nuclear translocation of nuclear factor-E2-related factor 2 (Nrf2). In addition, FGF19 promoted the activation of Nrf2-mediated antioxidant response element (ARE) antioxidant signaling. Notably, treatment with a GSK-3 beta inhibitor significantly abrogated the adverse effects of FGF19 silencing on H/R-induced injury, whereas silencing of Nrf2 partially blocked the FGF19-mediated cardioprotective effect against H/R-induced injury in cardiomyocytes. Taken together, our findings demonstrate that FGF19 alleviates H/R-induced apoptosis and oxidative stress in cardiomyocytes by inhibiting GSK-3 beta activity and promoting the activation of Nrf2/ARE signaling, providing a potential therapeutic target for prevention of myocardial injury. (C) 2018 Elsevier Inc. All rights reserved.