Serotonin receptor 2B induces visceral hyperalgesia in rat model and patients with diarrhea-predominant irritable bowel syndrome

Figure 6 Double-label immunofluorescence analysis in the rat colon. A and B: Double-label immunofluorescence analysis of serotonin receptor 2B (5-HT_2B receptor) (green) and transient receptor potential vanilloid type 1 (TRPV1) (red) in the colon mucosa layer (A) and muscular layer (B) in normal control rats, irritable bowel syndrome with diarrhea (IBS-D) + Vehilce rats and RS-127445-treated IBS-D rats. Merged image showing colocalization (yellow) of the 5-HT_2B receptor and TRPV1 immunoreaction. Magnification 20 ×; C: The data are the percentages of 5-HT_2B receptor I⁺ cells in the colon mucosa layer among the total 5-HT_2B receptor-immunoreactive (IR) cells in the colon mucosa layer (5-HT_2B receptor I_T); D: The data are presented as the percentage of 5-HT_2B receptor I⁺ cells in the colon muscular layer relative to the total 5-HT_2B IR cells in the colon muscular layer (5-HT_2B receptor I_T). ^aP < 0.05, ^bP < 0.01. IBS-D: Irritable bowel syndrome with diarrhea; 5-HT_2B: Serotonin receptor 2B; TRPV1: Transient receptor potential vanilloid type 1.