Expression of Serotonin Receptors in the Colonic Tissue of Chronic Diarrhea Rats

BACKGROUND/AIMS: This study aimed to investigate the difference among the expression of serotonin receptors (5-HT(3), 5-HT(4), and 5-HT(7) receptors) in colonic tissue of chronic diarrhea rats. MATERIALS AND METHODS: A rat model of chronic diarrhea was established by lactose diet. The expression of 5-HT(3), 5-HT(4), and 5-HT(7) receptors in the colonic tissue was detected using immunohistochemistry, real-time PCR and Western blotting techniques. RESULTS: There is no significant difference on the protein expression of 5-HT(3) receptor between the normal group and the chronic diarrhea model group. The mRNA expression of 5-HT(3) receptor in the chronic diarrhea model group was significantly lower than that in the normal group (n = 10; P < 0.01). The protein and mRNA expression of 5-HT(4) receptor in the chronic diarrhea model group were significantly higher than those in the normal group (n = 10; P < 0.05, P < 0.01). On the contrary, the protein and mRNA expressions of 5-HT(7) receptor in the chronic diarrhea model group were significantly decreased compared with the normal group (n = 10; P < 0.01, P < 0.01). CONCLUSIONS: The results suggested the receptors of 5-HT(4) and 5-HT(7) may be involved in inducing diarrhea by lactose diet.