Okumiya K, Fujimiya M
Department of Medicine and Geriatrics, Kochi Medical School, Japan.
Histochem Cell Biol. 1999 Apr;111(4):253-7. doi: 10.1007/s004180050355.
Recently we found that raising the intraluminal pressure caused an increase in the luminal release of serotonin from enterochromaffin (EC) cells and serotonin immunoreactivity normally restricted within the secretory granules was diffusely scattered over the extragranular matrix. In the present study we investigated the intracellular localization of chromogranin A, a protein co-stored with serotonin in the EC cells, after stimulating the luminal release of serotonin. In situ vascularly and luminally perfused rat duodenum was exposed to intraluminal pressure and fixed for immunoelectron microscopic study. For immunoelectron microscopy, the pre-embedding DAB reaction for serotonin combined with the postembedding immunogold reaction for chromogranin A was used. Results showed that a number of secretory granules labeled with immunogold chromogranin A immunoreactivity located close to the apical plasma membrane. Some EC cells showed that one part of the apical cytoplasm was protruded into the lumen and a number of secretory granules with immunogold labeling were included in the protruded cytoplasm. These results suggest that EC cells may release chromogranin A into the intestinal lumen together with serotonin, by means of a different manner of secretion from that in serotonin.
最近我们发现，提高管腔内压力会导致肠嗜铬（EC）细胞中5-羟色胺的管腔释放增加，并且通常局限于分泌颗粒内的5-羟色胺免疫反应性会扩散到颗粒外基质中。在本研究中，我们在刺激5-羟色胺的管腔释放后，研究了嗜铬粒蛋白A（一种与5-羟色胺共同储存在EC细胞中的蛋白质）的细胞内定位。对原位进行血管内和管腔内灌注的大鼠十二指肠施加管腔内压力，然后固定用于免疫电子显微镜研究。对于免疫电子显微镜，采用了用于5-羟色胺的包埋前DAB反应与用于嗜铬粒蛋白A的包埋后免疫金反应相结合的方法。结果显示，许多带有免疫金嗜铬粒蛋白A免疫反应性标记的分泌颗粒位于靠近顶端质膜处。一些EC细胞显示，顶端细胞质的一部分突出到管腔中，并且突出的细胞质中包含许多带有免疫金标记的分泌颗粒。这些结果表明，EC细胞可能通过一种与5-羟色胺不同的分泌方式，将嗜铬粒蛋白A与5-羟色胺一起释放到肠腔中。
