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表皮生长因子(EGF)是一个强大的促细胞分裂因子,对胃肠作用的研究大多集中于它对上皮细胞生长的控制。然而,这并不只是EGF的唯一作用。本文就EGF对胃肠道粘膜上皮分泌功能方面的影响作一综述。 1胃肠道EGF的来源 EGF是分子量为6KD的多肽,存在于唾液、十二指肠液、胰液和母乳中。进入肠腔的EGF在胃和十二指肠被加工成更小、活性较低的形式,最后经胰和小肠蛋白酶分解失去活性。 EGF除存在于分泌物中外,胃粘膜中也可测出低水平的EGF蛋白。在空肠绒毛和隐窝细胞、胎儿小肠上皮、成人结肠上皮和结肠癌细胞中均可测出EGF mRNA。然而,这些mRNA是否能翻译成活性EGF蛋白,还有待于进一步确定。血液中低水平的EGF被认为直接来源于唾液腺,而不是肠腔EGF的重吸收。虽然血液中EGF浓度还不到胃肠分泌物的1/5～1/20,但它对基础胃酸和最大胃酸分泌有直接作用。而且在某些
Epidermal growth factor (EGF) is a potent mitogen that most studies of gastrointestinal effects focus on its control of epithelial cell growth. However, this is not the only effect of EGF. This article reviews the effects of EGF on the secretion of gastrointestinal mucosal epithelium. 1 Sources of gastrointestinal EGF EGF is a polypeptide of 6KD molecular weight present in saliva, duodenal juice, pancreatic juice, and breast milk. Into the intestine, EGF is processed into smaller, less active forms in the stomach and duodenum, eventually losing activity via pancreatic and intestinal protease decomposition. EGF in addition to the presence of secretions, the gastric mucosa can also be measured low levels of EGF protein. EGF mRNA was detected in both jejunal villus and crypt cells, fetal intestinal epithelium, adult colorectal and colon cancer cells. However, whether these mRNAs can be translated into active EGF proteins remains to be determined. Low levels of EGF in the blood are thought to originate directly from the salivary glands rather than reabsorption of luminal EGF. Although the blood EGF concentration less than 1/5 ~ 1/20 of gastrointestinal secretions, but it has a direct effect on the basic gastric acid and maximum gastric acid secretion. And in some