Ternaux J P, Gonella J, Legay C, Faudon M, Barrit M C, Héry F
J Physiol (Paris). 1981;77(2-3):319-26.
The levels of TRP, 5-HTP, 5-HT and 5-HIAA were measured in the proximal colon of the rabbit using ion exchange chromatography and spectrofluorimetry. Assays were performed on fragments of the intact colonic wall, on the muscle layers containing nerve plexuses, and on the mucosa-containing enterochromaffin cells. In spite of identical TRP concentration, 5-HT levels were higher in the mucosa than in the muscle containing nerve plexus. In the muscle, the ratio 5-HIAA/5-HT was about 1, i.e., comparable to that of the brain, whereas the ratio was very low in the mucosa, suggesting a weak 5-HT catabolism in the enterochromaffin cells. When the mucosa was severed from the muscle, 5-HT synthesis was increased. In this case, 5-HT and 5-HIAA concentrations in the reconstituted wall (muscles + mucosa) were higher than in the intact wall. In in vitro studies, levels of newly synthesized (3H)5-HT from (3H)TRP were 3 times higher in the reconstituted wall than in the intact one, and the conversion index of TRP to 5-HT was higher in the mucosa and in the reconstituted wall respectively. These results suggest that enterochromaffin cells do synthesize 5-HT from TRP when the mucosa is divided from the muscle. (3H)5-HT was taken up by both nerve plexuses and mucosa, with a high affinity mechanism. Results from tryptophan loading experiments indicated that 5-HTP decarboxylase in the gut might be involved in the regulation of 5-HT synthesis. The mucosa severed from the muscles might represent a good model for the study of carcinoid tumour development.
采用离子交换色谱法和荧光分光光度法测定家兔近端结肠中色氨酸（TRP）、5-羟色氨酸（5-HTP）、5-羟色胺（5-HT）和5-羟吲哚乙酸（5-HIAA）的水平。检测在完整结肠壁碎片、含神经丛的肌层以及含肠嗜铬细胞的黏膜上进行。尽管TRP浓度相同，但黏膜中的5-HT水平高于含神经丛的肌层。在肌层中，5-HIAA/5-HT的比值约为1，即与脑内的比值相当，而在黏膜中该比值非常低，提示肠嗜铬细胞中5-HT的分解代谢较弱。当黏膜与肌层分离时，5-HT的合成增加。在这种情况下，重构壁（肌层 + 黏膜）中的5-HT和5-HIAA浓度高于完整壁。在体外研究中，重构壁中由（3H）TRP新合成的（3H）5-HT水平比完整壁高3倍，且TRP向5-HT的转化指数在黏膜和重构壁中分别更高。这些结果表明，当黏膜与肌层分离时，肠嗜铬细胞确实能从TRP合成5-HT。（3H）5-HT通过高亲和力机制被神经丛和黏膜摄取。色氨酸负荷实验结果表明，肠道中的5-HTP脱羧酶可能参与5-HT合成的调节。从肌层分离的黏膜可能是研究类癌肿瘤发生发展的良好模型。
