Significance of physiologic changes of quantity of enterochromaffin cells and expression of 5-hydroxytryptamine receptor 3 (5-HT3R) in SD rats at different ages / 中华老年医学杂志

ABSTRACT

Objective To study the changes of intestinal transit rate, quantity of enterochromaffin cells and expressions of 5-hydroxytryptamine receptor 3 (5-HT3R) in SD rats at different ages, and to investigate the possible mechanism of gastrointestinal dysfunction in aged rats. Methods Eighty healthy SD rats were divided into five groups three months age, nine months age, eighteen months age, twenty-four months age and thirty months age,and there were sixteen rats in each group. The intestinal transit rate was detected. Immunohistochemistry staining was used to test the quality of chromaffin cells in mucosa and submucosa of jejunum, ileum and colon and to detect the expressions of 5-HT3R in intestinal myenteric plexus. Results The intestinal transit rate was significantly lower in thirty months age group than in three months age group [(52.1±9.8)% vs. (67.2±13.5)%, t=7.013, P=0.001]. In thirty months age group, the quality of chromaffin cells in mucosa and submueosa of jejunum, ileum and colon were 11.1±3.0, 10.6±1.9, 10.2±4.3, respectively, which were reduced compared with three months age group (22.9±6.2, 25.8±7.1, 23.0±5.7, t=3. 640,3. 384,4. 154, all P<0.01). The expressions of 5-HT3R in myenteric plexus of jejunum and ileum were reduced in thirty months age group than in nine months age group [4.8±1.4, 9.3±4.2 vs. 8.9±1.5, 14.5±5.3;t=3.464, 3.003,all P<0.01]. The expression of 5-HT3R in colon myenteric plexus were 5.0±1.3 and 9.0±1.7 in thirty months age group and three months age group, respectively (t=4.549,P<0.001). Conclusions In aged rats, the intestinal transit rate, quantity of enterochromaffin cells and expressions of 5-HT3R are decreased with ageing, and the gastrointestinal dysfunction may be associated with the changing of the quantity of enterochromaffin cells and expressions of 5-HT3R in myenteric plexus.