Effects of serotonin level and HSC activation on krasV12-induced liver fibrosis. Three-month-old adult zebrafish were treated with dox with or without serotonin, BW23C86, PCPA, and SB204741 for 7 days. (A) IF staining of collagen I antibody and quantification of fibrotic liver tissue area in collagen I antibody–stained liver sections (n > 8 in each group). (B) Staining and quantification of fibrotic liver tissue area in Picrosirius Red–stained liver sections (n > 8 in each group). (C) Staining and quantification of fibrotic liver tissue area in Gomori’s trichrome–stained liver sections (n > 8 in each group). *P < .05. Scale bars: (A) 50 μm, and (B and C) 500 μm. DAPI, 4′,6-diamidino-2-phenylindole.