Fig. 3.

Total GI transit time, small intestine transit, and colonic motility are decreased in TPH2KO and TPH1/2dKO mice; however, gastric emptying is accelerated in the same animals. (A) Carmine red was administered orally and transit time was considered as the time required for the red color to appear in feces. GI transit time in TPH1KO, TPH2KO, and TPH1/2dKO mice was compared, respectively, to that of the wild-type littermates of each of these types of mouse. Total GI transit time was increased (slower than littermates) in TPH2KO and TPH1/2dKO animals but not in TPH1KO mice. Total GI transit time in TPH1/2dKO animals was not significantly different from that in TPH2KO mice. (B) Gastric emptying was measured after rhodamine dextran gavage. The proportion of gavaged rhodamine dextran emptying from the stomach in 15 minutes was compared in TPH1KO, TPH2KO, and TPH1/2dKO mice and their respective wild-type littermates. Gastric contents emptied to a greater extent in TPH2KO and TPH1/2dKO, but not in TPH1KO, animals than in their littermates. Gastric emptying in TPH1/2dKO animals was not significantly different from that in TPH2KO mice. (C) Small intestinal transit was evaluated as the geometric center of rhodamine dextran in the small bowel. Geometric centers of 1 to 10 represent slow to fast small intestine transit. Small intestinal transit was significantly slower in TPH2KO and TPH1/2dKO but not in TPH1KO animals than in their respective wild-type littermates. Small intestinal transit in TPH1/2dKO animals was not significantly different from that in TPH2KO mice. D. Colonic motility was estimated as the time for expulsion of a glass bead pushed into the rectum a distance of 2 cm from the anal verge. This time was significantly greater (slower motility) in TPH2KO and TPH1/2dKO but not in TPH1KO animals than in their respective wild-type littermates. Expulsion time in TPH1/2dKO mice was not significantly different from that in TPH2KO mice. (ns = not significant.) (From Li et al. [3].)