Anti-fibrosis effect of cardiac M3 receptor
We found that M3R was expressed in cardiac fibroblasts. M3R protein level was upregulated in both cardiac fibrotic mice and TGF-β1-induced cardiac fibroblasts. Choline significantly inhibited interstitial fibrosis, which was reversed by 4-DAMP. Protein expression of collagen I and III was reduced after choline treatment, and restored by 4-DAMP. Knockdown of endogenous M3R using siRNA increased collagen I expression. Furthermore, TGF-β1/Smad2/3 pathway and the p38MAPK signaling were found repressed by choline.