Baicalin inhibits pressure overload -induced cardiac fibrosis through regulating AMPK/TGF-P/Smads signaling pathway

AMP-activated protein kinase (AMPK) is a central regulator of multiple metabolic pathways. It has been shown that activation of AMPK could inhibit fibroblast proliferation and extracellular matrix (ECM) accumulation, thereby suppressing cardiac fibrosis. Baicalin, the major component found in skullcap, possesses multiple protective effects on the cardiovascular system. However, little is known about the effect of baicalin on cardiac fibrosis and the molecular mechanism by which baicalin exerts its anti-fibrotic effects has not been investigated. In this study, we revealed that baicalin could inhibit cell proliferation, collagen synthesis, fibronectin (FN) and Connective tissue growth factor (CTGF) protein expression in cardiac fibroblasts induced by angiotensin II (Ang II). It also ameliorated cardiac fibrosis in rats submitted to abdominal aortic constriction (AAC). Moreover, baicalin inhibited transforming growth factor-beta (TGF-beta)/Smads signaling pathway stimulated with Ang II through activating AMPK. Subsequently, we also demonstrated that baicalin attenuated Ang II-induced Smad3 nuclear translocation, and interaction with transcriptional coactivator p300, but promoted the interaction of p300 and AMPK. Taken together, these results provide the first evidence that the effect of baicalin against cardiac fibrosis may be attributed to its regulation on AMPK/TGF-beta/Smads signaling, suggesting the therapeutic potential of baicalin on the prevention of cardiac fibrosis and heart failure.