AD-9308 reduced cardiac fibrosis in streptozotocin (STZ)-induced diabetic mice. The mean mRNA levels of fibrosis markers, (a) transforming growth factor β1 (Tgf-β1), (b) connective tissue growth factor (Ctgf), (c) fibroblast-specific protein 1 (Fsp1), (d) periostin (Postn), (e) fibronectin (Fn-1), and (f) Tgf-β2, and (g) representative immunohistochemical staining of anti-α-smooth muscle actin (α-Sma)and anti-Collagen IV (Col IV) and mRNA levels of (h) α-Sma and (i) Col IV were detected in cardiac tissuesfrom STZ-induced diabetic mice treated with 0, 60, 180 mg/kg/day of AD-9308 by oral gavages and non-diabetic control mice. Data are presented as mean ± SEM (n = 14–16 per group). p-for-trend was used to test the linear trend. Scale bar, 20 μm.