Effects of berberine and its derivatives on α-SMA and collagen content and fibrous cap thickness in atherosclerotic plaques. ApoE−/− mice were fed with the Western diet for 16 weeks and then treated with BBR (B) or its derivatives, Di-MeBBR (C) and dhBBR (D) for 16 weeks. Mice receiving PBS served as the control group (A). Mouse aorta sections were collected. Immunohistochemistry and Masson’s trichrome staining were performed to determined the positive area of α-SMA,scale bar represents 100 μM (A) and collagen,scale bar represents 500 μM (B) content, respectively. The mean fibrous cap thickness was measured (C). *P < 0.05 vs. the control group.