Abstract
Nobiletin was found to protect against acute myocardial infarction (AMI)-induced cardiac function decline and myocardial remodeling, although the dose-effect relationship and underlying pathways remained unclear. In the current research, different doses of Nobiletin (7.5, 15 and 30 mg/kg/day) were administered to AMI rat model for 21 days. Survival rate, echocardiography, and histological analysis were assessed in vivo. In addition, MTT assay, flow cytometry, and Western blotting were conducted to explore Nobiletin's cytotoxicity and antiapoptotic effect on H9C2 cells. Mechanistically, the activation of MAPK effectors and p38 in vivo was studied. The results showed medium- and high-dose Nobiletin could significantly improve survival rate and cardiac function and reduce the area of infarction and cardiac fibrosis. Medium dose showed the best protection on cardiac functions, whereas high dose showed the best protective effect on cellular apoptosis and histological changes. JNK activation was significantly inhibited by Nobiletin in vivo, which could help to explain the partial contribution of autophagy to AMI-induced apoptosis and the discrepancy on dose-effect relationships. Together, our study suggested that JNK inhibition plays an important role in Nobiletin-induced antiapoptotic effect in myocardial infarction, and medium-dose Nobiletin demonstrated the strongest effect in vivo.