| [Objectives] To set up the visceral hypersensitivity rat model, and investigate the change of serotonin or 5-hydroxytryptamin(5-HT) enterochromaffin cell(EC cell),mast cell(MC)of colon in this model, and explore the correlation between 5-HT expression and visceral hypersensitivity in the rat colon.[Methods] 48 Sprague-Dawley rats (24 male and 24 female) were divided into 3 groups randomly. The rats of experiment 1 group and experiment 2 group were given chicken egg albumin by intraperitoneal injection, and control group gave sodium chloride by intraperitoneal injection. The colorectal balloon distention(CRD) were performed to evaluate the sensitivity of colon by the abdominal withdrawal reflex(AWR) after 2 weeks. Experiment 2 group gave MC membrane stabilizing agent(Sodium Cromoglicate)by intraperitoneal injection before distention. We made use of special staining to count MC and EC cell, immunohistochemistry to research 5-HT expression in the colon.Part of samples were used to observe ultrastructure of cells in colon by electron microscope.[Results]There were significant differences on the AWR scores of experiment 1 group,experiment 2 group and control group at the 1.0ml,1.5ml and 2.0ml distention (P<0.01).Contrasting between group and group,the scores of experiment 1 group and experiment 2 group were significant higher than control group. Between the 2 experiment groups,at 1.0ml and 1.5ml distention,there was no significant difference,but at the 2.0ml,we found significant difference (P<0.05). In the 2 experiment groups, the AWR scores of 1.0ml and 2.0ml distention of female rats significantly increased compared with male rats.In control group, the AWR scores of female rats was higher than the male at 1.0ml,1.5ml and 2.0ml distention (P<0.05). The colon found no obvious pathologic alteration in each group by Haematoxylin- Eosin(HE) staining. We found significant difference on the number of MC and EC cells of colon of each highpower field,the H-score of 5-HT positive cells in colon mucosa,the expression of 5-HT positive tissue in muscularis mucosa,submucosa layer and muscular layer among the 3 groups(P<0.05). Compared with control group, the number of MC and EC cells of colon increased significantly(P<0.01), the H-score of 5-HT positive cells in mucosa increased markedly(P<0.01), the expression of 5-HT positive tissue was significantly high in muscularis mucosa,submucosa layer and muscular layer in experiment groups(P<0.05).Between the 2 experiment groups,there were no significant differences on the number of MC and EC cell,the H-score of mucosa 5-HT positive cells,the expression of 5-HT positive tissue in muscular layer(P>0.05),but the expression of 5-HT positive tissue of in muscularis mucosa,submucosa layer in experiment 1 group was significant higher than experiment 2 group(P<0.05).It was shown that the AWR scores was positive correlative with H-score of 5-HT positive cells in mucosa and the expression of 5-HT positive tissue in muscularis mucosa and submucosa layer. Scanning electron microscope observations of the colon in experiment groups showed large secretive granules in EC cell and more high density granules in MC,and more vacuoles in experiment 1 group,presenting an active function and secreting state.[Conclusions] 1.Intraperitoneal injection of immune induction can induce colon visceral hypersensitivity absent of any identifiable pathologic alteration.Compared with the male rats,the female rats were allergized easily.2. The number of EC cells and MC are significantly increased in colon of the rats with visceral hypersensitivity, presenting an active function state. The quantity of 5-HT synthesis is increased markedly.3. The expression of 5-HT positive tissue in muscularis mucosa,submucosa layer which MC mediate effectively was significantly higher in rat colon of visceral hypersensitivity.4.The expression of 5-HT is correlated with the AWR score of visceral hypersentivity,it suggests that 5-HT is an important active factor in the visceral hypersentivity. |
PDF Full Text Request