肠道嗜铬细胞数量和5-羟色胺受体3表达在大鼠衰老过程中的变化及意义

目的 检测不同鼠龄SD大鼠肠道推进率、肠道黏膜嗜铬细胞数量和肠肌间神经丛5-羟色胺受体3(5-HT3R)的表达,探讨生理性衰老过程中肠道运动功能变化的规律及其机制. 方法 80只健康SD大鼠分为3月龄、9月龄、18月龄、24月龄及30月龄5组,每组各16只.以印度墨汁为标记物,检测大鼠的肠道推进率;采用免疫组化链霉亲和素-生物素-过氧化物酶复合物(SABC)法染色,检测大鼠空肠、回肠和结肠黏膜及黏膜下嗜铬细胞的数量以及肠肌间神经丛5-HT3R的表达.结果肠道推进率30月龄组大鼠为(52.1±9.8)%,明显低于3月龄组(67.2±13.5)%(t=7.013,P=0.001);30月龄组大鼠空肠、回肠及结肠黏膜和黏膜下嗜铬细胞数量分别为(11.1±3.0)个、(10.6±1.9)个和(10.2±4.3)个,较3月龄组(22.9±6.2)个、(25.8±7.1)个和(23.0±5.7)个减少(t=3.640,t=3.384,t=4.154,均为P<0.01);大鼠空肠和结肠的5-HT3R表达30月龄组分别为4.8±1.4和9.3±4.2,较9月龄组的8.9±1.5和14.5±5.3减少(t=3.464,t=3.003,均为P<0.01),回肠5-HT3R 30月龄组和3月龄组分别为5.0±1.3和9.0±1.7(t=4.549,P<0.001). 结论 老年大鼠肠道推进率、肠道嗜铬细胞数量及肠肌间神经丛5-HT3R表达均显著降低,并随年龄增长而逐渐明显;老年大鼠肠道运动功能的明显下降与肠嗜铬细胞数量以及肌间神经丛5-HT3R的表达显著降低有一定的相关性.

Significance of physiologic changes of quantity of enterochromaffin cells and expression of 5-hydroxytryptamine receptor 3 (5-HT3R) in SD rats at different ages

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.