MMPs play an important role in tissue modeling and damage in IBD [31, 41], and the proteolytic activity of MMPs is tightly regulated by their natural inhibitors, TIMPs [29, 30]; we explored whether MMP-2, MMP-3, MMP-9, TIMP-1, and TIMP-2 mRNA expressions are induced by 5-HT in mouse colons. This evidence concerns the gene MMP9 and inflammatory bowel disease.