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

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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.