Regulatory role of seronin-containing cells in the gastrointestinal tracts

在大鼠十二指肠血管灌流模型上，研究了肠嗜铬细胞(EC)分泌5-羟色胺(5-HT)的调节机制。结果表明，胆碱能神经通过EC细胞基底部位的M受体刺激肠腔内5-羟色胺的释放，而VIP和PACAP神经则通过巴塞尔部位的VIP-2受体抑制5-羟色胺的腔内释放。VIP受体在一氧化氮存在时起抑制作用。免疫电子显微镜研究证实了5-羟色胺和嗜铬素A从EC细胞腔内释放的形态证据。在灌流肠段观察5-羟色胺对肠运动的影响。结果表明，5-羟色胺对维持血液灌流强度有重要作用。此外，通过建立大鼠溃疡性结肠炎模型，探讨了5-羟色胺在炎症性肠病发病机制中的作用。含5-羟色胺的EC细胞和肥大细胞密度及组织中5-羟色胺含量明显增加，以近端和远端结肠最为明显。这些结果提示，5-羟色胺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.