Ginsenoside Rg3 inhibits angiotensin II-induced cardiac fibrosis via the glucagon-like peptide-1 receptor signaling pathway

INTRODUCTION: Cardiac fibrosis is a major pathological feature of multiple cardiovascular diseases and an important risk factor for heart failure. Ginsenoside Rg3 (Rg3), a natural triterpenoid saponin extracted from Panax ginseng, has been shown to exert cardioprotective effects. In this study, we assessed the effects of Rg3 on angiotensin II (Ang II)-induced cardiac fibrosis in both cellular and animal models and investigated the underlying mechanisms. MATERIAL AND METHODS: For the cellular experiments, primary mouse cardiac fibroblasts (CFs) were treated with Ang II (1 μM) and Rg3 (25, 50, or 100 μM) for 24 h to assess the effects of Rg3 on cardiac fibrosis in vitro. The glucagon-like peptide-1 receptor (GLP-1R) antagonist exendin-3 (9-39) (1 μM) was used to validate the role of GLP-1R signaling in the anti-fibrotic effects of Rg3 in vitro. A CCK-8 assay was performed to assess cell viability. For the animal experiments, male C57BL/6J mice were divided into 4 groups (6 mice per group): Sham, Ang II, Ang II + Rg3 (50 mg/kg), and Ang II + Rg3 (100 mg/kg). Collagen deposition in mouse cardiac tissues was assessed by picrosirius red staining. The expression of fibrosis-related proteins (MMP-2, MMP-9, α-SMA, collagen I, collagen III, and fibronectin), GLP-1R, phosphorylated Smad2/3, total Smad2/3, RhoA, and ROCK2 in CFs and mouse cardiac tissues was examined by RT-qPCR, western blotting, and immunofluorescence staining. RESULTS: Rg3 treatment reversed the Ang II-induced upregulation of MMP-2, MMP-9, α-SMA, collagen I, collagen III, p-Smad2/3, RhoA, and ROCK2 and the downregulation of GLP-1R in CFs. Exendin-3 (9-39) antagonized the effects of Rg3 on the expression of fibrosis-related proteins, GLP-1R, p-Smad2/3, RhoA, and ROCK2 in CFs. Furthermore, Rg3 administration suppressed collagen deposition, reduced the expression of MMP-2, MMP-9, α-SMA, collagen I, collagen III, p-Smad2/3, RhoA, and ROCK2, and increased GLP-1R levels in the cardiac tissues of Ang II-infused mice. CONCLUSIONS: Rg3 exerts an anti-fibrotic effect in cardiac fibrosis models by inhibiting activation of the RhoA/ROCK and Smad2/3 pathways through upregulation of GLP-1R.