Acute and Chronic Responses of Pancreatic Exocrine Protease Secretion to Different Dietary Proteins and Oligomethionine in Rats

1.饲粮蛋白质对与胰腺外分泌蛋白酶分泌相关的低聚蛋氨酸消化率的急性影响：当8%酪蛋白（8C）饲粮中添加0.3%低聚蛋氨酸（六肽和七肽的混合物，简称OM）时，断奶大鼠的生长速度与添加蛋氨酸的饲粮相同。然而，在10%大豆分离蛋白（10S）饲粮中添加OM时，几乎没有观察到生长促进作用。8C+30M的空腹大鼠门脉血浆Met浓度显著高于8C、10S、10S+30M的空腹大鼠，且与预先饲喂的蛋白质无关。饲喂不同蛋白质饲料（含30M）后，空腹大鼠门脉Met浓度的增幅依次较高；扇贝、大米、麸质、金枪鱼、鲑鱼、花生、土豆和鳕鱼。在低马铃薯或低鳕鱼日粮中添加OM，大鼠的体重增加低于添加met的大鼠。另一方面，与基础饮食喂养的大鼠相比，在低麸质、金枪鱼或花生饮食中补充OM显著提高了大鼠的生长。此外，在麸质、酶水解物或氨基酸混合日粮中添加OM的不同效果与在这些日粮中添加30M.2的大鼠门脉Met增加的结果非常一致。慢性摄入OM导致胰腺蛋白酶和OM消化的适应性增加：当大鼠在8C、8C+30M条件下进食2周时，饲喂OM的大鼠胰腺羧肽酶活性更高。只有先前食用OM的大鼠在重新喂食含有OM的饮食后，门静脉血中的Met浓度明显升高。

1.Acute effects of dietary proteins on the rate of oligomethionine digestion associated with pancreatic exocrine protease secretion: When 8% casein (8C) diet was supplemented with 0.3% oligomethionine (a mixture of hexa-and hepta-peptides, abbreviated as OM) weanling rats grew at the same rate as that attained with Met-supplemented diet. When OM was supplemented to 10% soybean protein isolate (10S) diet, however, little or no growth promotion was observed.Met concentration of the portal blood plasma from fasting rats refed 8C+30M was significantly higher than that of rats refed 8C, 10S, 10S+30M, irrespective of prefed dietary proteins. Increment of portal Met concentration in fasting rats refed different protein diets containing 30M was high in the order of the following diets; scallop, rice, hluten, tuna, salmon, peanut, potato and cod. On the supplementation of OM to a low potato or cod diet, the weight gain in rats was lower than that of rats fed the Met-supplemented diet. On the other hand, supplementation of OM to a low gluten, tuna or peanut diet increased significantly the growth of rats as compared with that of the basal diet-fed rats. Also, the different effect of OM supplemented to gluten, the enzyme hydrolysate or amino acid mixture diet agreed very closely with the result of portal Met increment from rats refed these diets containing 30M.2.Adaptive increase in pancreatic proteases and OM-digestion due to chronic ingestion of OM: When rats prefed 8C, 8C+30M for 2 weeks, pancreatic carboxypeptidase activity was higher in rats fed OM-containing diet. Only the rats previously consumed OM showed a significantly higher Met concentration in the portal blood in response to refeeding the OM-containing diet.