Cetin Y, Kuhn M, Kulaksiz H, Adermann K, Bargsten G, Grube D, Forssmann W G
Department of Anatomy, Hannover Medical School, Federal Republic of Germany.
Proc Natl Acad Sci U S A. 1994 Apr 12;91(8):2935-9. doi: 10.1073/pnas.91.8.2935.
Guanylin, a bioactive peptide, has recently been isolated from the intestine; this peptide activates intestinal guanylate cyclase (i.e., guanylate cyclase C) and thus is potentially involved in the regulation of water/electrolyte transport in the gastrointestinal mucosa. As yet, the cells involved in synthesis, storage, or secretion of guanylin have not been identified by immunocytochemistry. We raised antisera against guanylin and investigated the entire gastrointestinal tract of guinea pigs by light and electron microscopical immunocytochemistry. Extracts of various intestinal segments and plasma analyzed on a Western blot revealed a peptide band corresponding to the molecular mass of guanylin. Localization studies in the entire digestive tract showed that guanylin is exclusively confined to enterochromaffin (EC) cells. Remarkably, most EC cells contacted the gut lumen by cell processes that were highly immunoreactive for guanylin. In addition to the well known secretion in an endocrine fashion, EC cells by circumstantial evidence may release guanylin into the gut lumen to activate guanylate cyclase C that is immediately located on the brush border of adjacent enterocytes. The unique localization of guanylin in EC cells may indicate that these cells are involved in the regulation of fluid secretion in the gastrointestinal mucous membrane.
鸟苷林是一种生物活性肽，最近从肠道中分离出来；这种肽可激活肠道鸟苷酸环化酶（即鸟苷酸环化酶C），因此可能参与胃肠道黏膜中水/电解质转运的调节。迄今为止，尚未通过免疫细胞化学鉴定出参与鸟苷林合成、储存或分泌的细胞。我们制备了抗鸟苷林抗血清，并通过光镜和电镜免疫细胞化学方法对豚鼠的整个胃肠道进行了研究。在蛋白质印迹上分析各种肠段提取物和血浆，发现了一条与鸟苷林分子量相对应的肽条带。对整个消化道的定位研究表明，鸟苷林仅局限于肠嗜铬（EC）细胞。值得注意的是，大多数EC细胞通过对鸟苷林具有高度免疫反应性的细胞突起与肠腔接触。除了众所周知的内分泌方式分泌外，根据间接证据，EC细胞可能将鸟苷林释放到肠腔中，以激活紧邻相邻肠上皮细胞刷状缘的鸟苷酸环化酶C。鸟苷林在EC细胞中的独特定位可能表明这些细胞参与了胃肠道黏膜中液体分泌的调节。
