Abstract
Cardiomyocyte apoptosis, neural remodeling, and gap junction channel change play critical roles in ventricular arrhythmia (VA) after acute myocardial infarction (AMI). Urolithin B (UB), one of the gut metabolites of ellagitannins, a class of antioxidant polyphenols, has various biological activities, but its direct role in cardiomyocyte apoptosis, neural remodeling, and gap junction channel change after AMI remains elusive. We investigated whether urolithin B reduced susceptibility of myocardial arrhythmic after myocardial infarction (MI). In vitro, the cardiomyocytes were subjected to hypoxia (94% N2/5% CO2/1% O2) for 3 hours. Cardiomyocyte apoptosis was assessed by TUNEL staining and western blotting. Urolithin B was found to decrease the number of apoptotic cells after hypoxia. Moreover, there was a substantial decrease in the expression of neural remodeling markers in the urolithin B treatment group. Urolithin B significantly increased the expression level of gap junction channel protein. Mechanistically, urolithin B inhibited cardiomyocyte apoptosis by activating Akt/the mammalian target of rapamycin (mTOR) pathway, and the protection of urolithin B against cardiomyocyte apoptosis was compromised with Akt gene silencing. Furthermore, urolithin B suppressed nuclear translocation of nuclear factor-kB (NF-κB) to facilitate nerve remodeling. Taken together, our findings suggested that UB reduced the occurrence of myocardial arrhythmias after hypoxia via regulation of the Akt/mTOR pathway and NF-κB nuclear translocation, which highlights the potential of UB as a novel therapy for ischemic heart disease.