HTR1A and colitis: Accordingly, we first verified the increase in colonic 5-HT content in TNBS-induced colitis; second, we evaluated the effects produced by the repeated administration of selective antagonists of 5-HT1A (WAY100135), 5-HT2A (Ketanserin), 5-HT3 (Ondansetron), 5-HT4 (GR125487), and 5-HT7 (SB269970) receptors in the same experimental model.