Syringic acid mitigates myocardial ischemia reperfusion injury by activating the PI3K/Akt/GSK-3β signaling pathway

Syringic acid is an abundant phenolic acid compound that possesses anti-oxidant, anti-microbial, anti-inflammatory, and anti-endotoxic properties. However, the research of pretreatment with syringic acid against myocardial ischemia reperfusion is still limited. Thus, our research revealed the protective effect of syringic acid in the rat model with myocardial ischemia reperfusion injury. Histological analysis was performed by hematoxylin and eosin (H&E). The myocardial systolic function was detected by echocardiographic. Myocardial infarct size was measured by Evans blue and 2,3,5-triphenyltetrazolium chloride (TTC) double staining. The apoptosis index was recorded by Terminal deoxynucleotidyl transferase dUTP nick end labeling staining (TUNEL). The contents of creatine kinase MB (CK-MB) and lactate dehydrogenase (LDH) in the serum were determined by a commercial kit. The expression of the PI3K/Akt/GSK-3β signaling pathway-related molecules and apoptosis-associated indicators was detected by western blotting or real-time PCR. We found that pretreatment with syringic acid obviously increased the myocardial systolic function (LVEF and LVFS) and decreased the infarct size, the apoptosis index as well as the serum level of CK-MB and LDH. Meanwhile, syringic acid also remarkably augmented the contents of p-PI3K, p-Akt, p-GSK-3β, Bcl-2 and mitochondria cytochrome c. However, the expression of caspase-3, -9 and Bax significantly reduced. Interestingly, co-treatment with PI3K inhibitor of LY294002 counteracted those effects induced by syringic acid. In conclusion, pretreatment with syringic acid can mitigate myocardial ischemia reperfusion injury by inhibiting mitochondria-induced apoptosis which is regulated by the PI3K/Akt/GSK-3β signaling pathway.