Hirano T, Manabe T, Printz H, Saluja A, Steer M
First Department of Surgery, Faculty of Medicine, Kyoto University, Japan.
Nihon Geka Hokan. 1992 Mar 1;61(2):103-24.
To investigate the possible secretion of lysosomal enzymes into pancreatic juice during stimulation with a pancreatic secretagogue under both physiological and pathological conditions, we measured the amount of cathepsin B, a lysosomal enzyme, in the pancreatic juice during the infusion of 6 different concentrations of caerulein (0.02, 0.05, 0.2, 0.5, 1.0, and 2.0 micrograms/kg. hr). In one group of rabbits the pancreatic duct was only cannulated (free-flow group); in others the pancreatic duct was obstructed for 7 hours and secretin was infused at 0.2 CU/kg. hr (obstructed group). In addition, we evaluated the effect of the intraduodenal instillation of a liquid meal (2 g/kg) on the secretion of lysosomal enzymes into pancreatic juice. Caerulein stimulated the secretion of cathepsin B into pancreatic juice in a dose-dependent manner, as it did that of amylase, and at higher concentrations of caerulein (1.0 and 2.0 micrograms/kg. hr), both cathepsin B output and amylase output were decreased. There was a significant positive correlation between cathepsin B output and amylase output into pancreatic juice during stimulation with caerulein. Blockage of the pancreatic duct for 7 hours caused a significant rise in serum amylase levels and a redistribution of cathepsin B activity in the pancreatic subcellular fractions, as a result of which an increased amount of cathepsin B was recovered in the pellet obtained by 1000 x g centrifugation for 15 min, which contained many zymogen granules. These changes noted after short-term pancreatic duct obstruction are very similar to those previously noted in the early stage of diet-and caerulein-induced experimental pancreatitis, suggesting the colocalization of lysosomal enzyme and digestive enzymes. In the duct-obstructed animals, the secretion of cathepsin B stimulated by caerulein was significantly greater than in the free-flow group. Furthermore, the intraduodenal instillation of a liquid meal caused the secretion of cathepsin B into the pancreatic juice along with amylase. These results indicate that under physiological conditions, such as food intake, lysosomal enzymes are secreted into the pancreatic juice in response to stimulation by gut hormones in the same manner as classical pancreatic digestive enzymes. Moreover, zymogen colocalized with lysosomal enzymes in duct-obstructed animals is secreted into pancreatic juice in increased amounts together with digestive enzymes; this finding suggests that lysosomal enzymes play important pathophysiological roles in pancreatic juice and that acinar cells are altered to maintain cellular organization by secreting the potentially dangerous lysosomal enzymes. This pancreatic duct-obstructed rabbit model should be useful in clarifying the early events of acute pancreatitis.
为了研究在生理和病理条件下，用促胰液素刺激时溶酶体酶是否可能分泌到胰液中，我们在输注6种不同浓度的雨蛙素（0.02、0.05、0.2、0.5、1.0和2.0微克/千克·小时）期间，测量了胰液中溶酶体酶组织蛋白酶B的含量。在一组兔子中，仅对胰管进行插管（自由引流组）；在其他兔子中，胰管阻塞7小时，然后以0.2 CU/千克·小时的速度输注促胰液素（阻塞组）。此外，我们评估了十二指肠内灌注流食（2克/千克）对溶酶体酶分泌到胰液中的影响。雨蛙素以剂量依赖的方式刺激组织蛋白酶B分泌到胰液中，就像它对淀粉酶的刺激一样，并且在较高浓度的雨蛙素（1.0和2.0微克/千克·小时）下，组织蛋白酶B的分泌量和淀粉酶的分泌量均下降。在用雨蛙素刺激期间，组织蛋白酶B的分泌量与胰液中淀粉酶的分泌量之间存在显著的正相关。胰管阻塞7小时导致血清淀粉酶水平显著升高，并且组织蛋白酶B活性在胰腺亚细胞组分中重新分布，结果是在通过1000×g离心15分钟获得的沉淀中回收了更多的组织蛋白酶B，该沉淀中含有许多酶原颗粒。短期胰管阻塞后观察到的这些变化与先前在饮食和雨蛙素诱导的实验性胰腺炎早期观察到的变化非常相似，这表明溶酶体酶和消化酶共定位。在胰管阻塞的动物中，雨蛙素刺激的组织蛋白酶B分泌量明显大于自由引流组。此外，十二指肠内灌注流食导致组织蛋白酶B与淀粉酶一起分泌到胰液中。这些结果表明，在生理条件下，如进食时，溶酶体酶会像经典的胰腺消化酶一样，响应肠道激素的刺激而分泌到胰液中。此外，在胰管阻塞的动物中，与溶酶体酶共定位的酶原会与消化酶一起以增加的量分泌到胰液中；这一发现表明溶酶体酶在胰液中发挥重要的病理生理作用，并且腺泡细胞通过分泌潜在危险的溶酶体酶而发生改变以维持细胞组织。这种胰管阻塞的兔子模型应该有助于阐明急性胰腺炎的早期事件。
