Liquiritigenin attenuates isoprenaline-induced myocardial fibrosis in mice through the TGF-β1/Smad2 and AKT/ERK signaling pathways

Myocardial fibrosis is a pathological process characterized by excessive accumulation of extracellular matrix in myocardial interstitial spaces. Myocardial fibrosis is a fundamental process in ventricular remodeling and a primary contributor to the progression of heart failure. Liquiritigenin (LQ) is a flavanone compound with anti-oxidative, anti-carcinogenic, anti-inflammatory and estrogenic properties. The present study aimed to investigate the regulatory potential of LQ treatment in a mouse model of isoprenaline (ISO)-induced cardiac fibrosis and in cultured H9C2 cardiomyocytes stimulated with angiotensin II (Ang II). The treatment of ISO-induced mice with LQ significantly decreased the levels of cardiac injury-related proteins in the serum and ECM accumulation in mouse heart tissues. LQ treatment also effectively alleviated cardiac dysfunction in ISO-treated mice. Further analyses revealed that LQ inhibited ISO-induced collagen formation and activation of the transforming growth factor-β1 (TGF-β1)/Smad2 and protein kinase B (AKT)/extracellular signal-regulated kinase (ERK) signaling pathways. As a major pathological event in myocardial fibrosis, the apoptosis of cardiomyocytes has been considered a key mechanism contributing to impaired left ventricle performance. The pretreatment of rat cardiomyocytes with LQ significantly reduced the apoptosis of H9C2 cells, and inhibited Ang II-induced activation of the TGF-β1/Smad2 and AKT/ERK pathways. In conclusion, the present study revealed that LQ ameliorated ISO-induced myocardial fibrosis in mice and inhibited the apoptosis of cardiomyocytes in vitro by inhibiting the TGF-β1/Smad2 and AKT/ERK signaling pathways. These results suggested the anti-fibrotic and cardioprotective potential of LQ in fibrosis, thus supporting the use of LQ for the management of cardiomyocyte injury and myocardial fibrosis in patients with cardiac diseases.