Involvement of enterochromaffin (EC) cells in diarrhea

1.产生5-羟色胺的EC细胞和VIP神经广泛分布于消化道，被认为是参与肠道分泌调节的最重要的细胞。双重免疫染色显示细胞和神经密切相关。2.犬十二指肠环的体内生理实验支持这样的观点：腹泻是由EC细胞释放的5-羟色胺介导的，导致邻近神经VIP的肝脏；两个信使串联和并行工作，相互加强作用。3.垂体腺苷环化酶激活多肽(PACAP)被证明强烈激活肠上皮的离子转运。通过刺激胆碱能和非胆碱能神经，PACAP可间接增强其对胆碱能和非胆碱能神经的作用。4.使用特异性拮抗剂的实验表明，5-HT3和5-HT4是参与肠道分泌的5-羟色胺受体类型。5.葡萄球菌肠毒素A(SEA)以前被认为是引起严重呕吐的原因，它能引起狗的肠道分泌明显增强(腹泻)；电子显微镜检查表明，EC细胞释放的5-羟色胺参与其中。

1.Serotonin-producing EC cells and VIP-containing nerves are distributed extensively in the digestive tract and are believed to be most importantly involved in the regulation of intestinal secretion. Double immunostaining demonstrated intimate association of the cells and the nerves.2.Physiological expe ; riments in vivo using canine duodenal loops support the view that diarrhea is mediated by serotonin released from EC cells, which causes liveration of VIP from vicinal nerves ; both messengers working in series as well as in parallel, potentiating the effect of each other.3.PACAP (Pituitary Adenylate Cyclase-Activating Polypeptide) was demonstrated to intensely activate ion transport in the intestinal epithelium. Enhancement by PACAP by C1^- release was shown to be an indirect effect via stimulation of cholinergic and non-cholinergic nerves.4.Experiments using specific antagonists indicated 5-HT_3 and 5-HT_4 as the types of serotonin receptors involved in intestinal secretion.5.SEA (Staphylococeal Enterotoxin A), previously know as causeing severe vomit, was demonstrated to cause a marked enhancement of intestinal secretion (diarrhea) in dogs ; involvement of serotonin released from EC cells was suggested by electron microscope examination of the cells.