Herzig K H, Schön I, Tatemoto K, Ohe Y, Li Y, Fölsch U R, Owyang C
Department of Internal Medicine, Christian-Albrechts-University Kiel, Germany.
Proc Natl Acad Sci U S A. 1996 Jul 23;93(15):7927-32. doi: 10.1073/pnas.93.15.7927.
Pancreatic proteases in the duodenum inhibit the release of cholecystokinin (CCK) and thus exert feedback control of pancreatic exocrine secretion. Exclusion of proteases from the duodenum either by the diversion of bile-pancreatic juice or by the addition of protease inhibitors stimulates exocrine pancreatic secretion. The mechanism by which pancreatic proteases in the duodenum regulate CCK secretion is unknown. In this study, we isolated a trypsin-sensitive peptide that is secreted intraduodenally, releases CCK, and stimulates pancreatic enzyme secretion in rats. This peptide was found to be identical to the porcine diazepam binding inhibitor by peptide sequencing and mass spectrometry analysis. Intraduodenal infusion of 200 ng of synthetic porcine diazepam binding inhibitor1-86 in rats significantly stimulated pancreatic amylase output. Infusion of the CCK antagonist MK-329 completely blocked the diazepam binding inhibitor-stimulated amylase secretion. Similarly, diazepam binding inhibitor33-52 [corrected] also stimulated CCK release and pancreatic secretion in a dose-dependent manner although it was 100 times less potent than the whole peptide. Using a perfusion system containing isolated mucosal cells from the proximal intestine of rats, porcine diazepam binding inhibitor 10(-12) M) dose dependently stimulated CCK secretion. In separate studies, it was demonstrated that luminal secretion of the diazepam binding inhibitor immunoreactivity (7.5 X 10(11) M) could be detected in rat's intestinal washing following the diversion of bile-pancreatic juice. The secretion of this peptide was inhibited by atropine. In conclusion, we have isolated and characterized a CCK-releasing peptide that has a sequence identical to the porcine diazepam binding inhibitor from pig intestinal mucosa and that stimulates CCK release when administered intraduodenally in rat. This peptide may mediate feedback regulation of pancreatic enzyme secretion.
十二指肠中的胰腺蛋白酶会抑制胆囊收缩素（CCK）的释放，从而对胰腺外分泌进行反馈控制。通过胆汁胰液改道或添加蛋白酶抑制剂将蛋白酶排除在十二指肠外，会刺激胰腺外分泌。十二指肠中的胰腺蛋白酶调节CCK分泌的机制尚不清楚。在本研究中，我们分离出一种对胰蛋白酶敏感的肽，该肽在十二指肠内分泌，能释放CCK，并刺激大鼠胰腺酶分泌。通过肽测序和质谱分析发现，该肽与猪地西泮结合抑制剂相同。向大鼠十二指肠内注入200 ng合成猪地西泮结合抑制剂1 - 86可显著刺激胰腺淀粉酶分泌。注入CCK拮抗剂MK - 329可完全阻断地西泮结合抑制剂刺激的淀粉酶分泌。同样，地西泮结合抑制剂33 - 52[校正后]也以剂量依赖的方式刺激CCK释放和胰腺分泌，尽管其效力比整个肽低100倍。使用含有大鼠近端肠道分离黏膜细胞的灌注系统，猪地西泮结合抑制剂（10(-12) M）剂量依赖性地刺激CCK分泌。在单独的研究中，已证明在胆汁胰液改道后，大鼠肠道冲洗液中可检测到地西泮结合抑制剂免疫反应性的腔内分泌（7.5×10(11) M）。该肽的分泌受阿托品抑制。总之，我们已从猪肠黏膜中分离并鉴定出一种CCK释放肽，其序列与猪地西泮结合抑制剂相同，在大鼠十二指肠内给药时可刺激CCK释放。该肽可能介导胰腺酶分泌的反馈调节。
