Ginsenoside Rg3 inhibits Ang II-induced cardiac fibrosis via the GLP-1 receptor signaling pathway

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.

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.

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.

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.