Regulatory role of seronin-containing cells in the gastrointestinal tracts

在离体大鼠十二指肠血管和管腔灌流模型上，研究了肠嗜铬细胞释放5-羟色胺（5-HT）的调节机制。结果表明，胆碱能神经可通过EC细胞基底部位的M受体刺激5 HT向肠腔的释放，VIP和PACAP神经则通过EC细胞巴塞尔部位的VIP 2型受体抑制5 HT向肠腔的释放。VIP受体在一氧化氮存在下发挥抑制作用。免疫电镜观察显示，EC细胞内有5-HT和嗜铬粒蛋白A的释放。在灌流肠中检测5 HT在肠运动活动中的作用。结果表明，5-HT在维持心肌灌注强度方面起重要作用。此外，5-HT在炎症性肠病发病机制中的作用也通过使用大鼠溃疡性结肠炎模型进行了检查。含5 HT的EC细胞和肥大细胞密度以及组织中5 HT含量均显著增加，尤其是在近端和远端结肠。提示5-HT在调节胃肠功能中起重要作用。

The mechanism to regulate the release of serotonin (5HT) from the enterochromaffin (EC) cells was investigated in the isolated vascularly and luminary perfused rat duodenum. Results showed that cholinergic nerves stimulated the luminal release of 5HT into the intestinal lumen via muscarinic receptors on the basal site of the EC cells, while VIP-and PACAP-containing nerves inhibited the luminal release of 5HT via VIP type 2 receptor on the basel site of EC cells. VIP receptor exerted the inhibitory effects in the presence of nitric oxide. Immunoelectron microscopic study demonstrated the morphological evidence for the luminal release of 5HT and chromogranin A from the EC cells. The effect of 5HT in the motor activity of the intestine was examined in the perfused intestine. Results showed that 5HT played an important role to keep the perfused intenstine. Furthermore the role of 5HT in the pathogenesis of inflammatory bowel disease was also examined by using the rat model of ulcerative colitis. The density of 5HT-containing EC cells and mast cells as well as the tissue 5HT content was significantly increased especially in the proximal and distal colon. These results suggest that 5HT plays an important role to regulate the gastrointestinal functions.