Reinecke M, David I, Loffing-Cueni D, Ablinger P, Cetin Y, Kuhn M, Forssmann W G
Institute of Anatomy, University of Zürich-Irchel, Switzerland.
Histochem Cell Biol. 1996 Oct;106(4):367-74. doi: 10.1007/BF02473295.
The peptide guanylin, recently isolated from the intestine, and localized to cells of the gut mucosa, is involved in electrolyte/water transport in the intestinal epithelium by means of a paracrine mode of regulation. Since high amounts of this peptide are present also in the systemic circulation, we investigated the adrenal gland as a potential endocrine source of guanylin. Using a reverse transcriptase-polymerase chain reaction and hybridization with an internal oligonucleotide designed for rat guanylin, 514-bp signals were obtained in intestinal tissue and adrenal gland. Successive analyses of extracts from intestine and adrenal gland by HPLC, western blotting, and radioimmunoassay revealed the presence of the same high-molecular mass (about 12.4 kDa) guanylin that corresponds to the mass of the guanylin prohormone. About 60 fmol/ml of circulating immunoreactive guanylin was determined in plasma. Localization studies with antisera directed against different epitopes of guanylin revealed that, in the adrenal gland, guanylin immunoreactivity is restricted to the medulla, where it is mainly confined to norepinephrine chromogranin A-containing cells. On the ultrastructural level, guanylin immunoreactivity was exclusively located to secretory granules of chromaffin cells. The present data indicate that, in addition to entero-endocrine cells, the adrenal medulla represents a further source of guanylin. Thus, an endocrine mode of function of guanylin may accrue to its hitherto evidenced paracrine action in fluid transport in the intestinal epithelium. Furthermore guanylin may be considered as a neurohormonal peptide.
肽鸟苷素最近从肠道中分离出来，定位于肠黏膜细胞，通过旁分泌调节方式参与肠上皮中的电解质/水转运。由于该肽在体循环中也大量存在，我们研究了肾上腺作为鸟苷素潜在内分泌来源的情况。使用逆转录聚合酶链反应并与为大鼠鸟苷素设计的内部寡核苷酸杂交，在肠道组织和肾上腺中获得了514 bp的信号。通过高效液相色谱、蛋白质印迹和放射免疫测定对肠道和肾上腺提取物进行的连续分析显示，存在与鸟苷素前激素质量相对应的相同高分子量（约12.4 kDa）的鸟苷素。血浆中测定的循环免疫反应性鸟苷素约为60 fmol/ml。用针对鸟苷素不同表位的抗血清进行的定位研究表明，在肾上腺中，鸟苷素免疫反应性仅限于髓质，主要局限于含去甲肾上腺素嗜铬粒蛋白A的细胞。在超微结构水平上，鸟苷素免疫反应性仅位于嗜铬细胞的分泌颗粒中。目前的数据表明，除了肠内分泌细胞外，肾上腺髓质也是鸟苷素的另一个来源。因此，鸟苷素的内分泌功能模式可能与其迄今在肠上皮液体转运中所证明的旁分泌作用共同存在。此外，鸟苷素可被视为一种神经激素肽。
