Utilization of Enzymatically Hydrolyzed Soybean Protein and Crystalline Amino Acid Diets by Rats with Exocrine Pancreatic Insufficiency

ABSTRACT Exocrine pancreatic-deficient rats (PD) were prepared by cannulation and ligation of the common duct in a way which permitted bile, but not pancreatic juice, to enter the intestine. After surgery the PD rats were fed purified diets containing a high quality nitrogen source in the form of crystalline amino acids (AA), an enzymatic hydrolysate of soybean protein supplemented with essential amino acids (EH) or intact soybean protein with an essential amino acid supplement (SP). PD rats fed SP failed to regain any of their surgically-induced weight loss during the 10-day postoperative period. PD rats fed AA did not resume weight gains until after the sixth postoperative day while those fed diet EH resumed growth by the third postoperative day and grew at a rate which was nearly identical to that observed in sham-operated controls. The three diets afforded almost identical growth rates in weanling rats and in sham-operated rats used as controls for the PD rats. The amino acid compositions of AA and EH were nearly identical. Thus, the better utilization of diet EH in the PD rats was attributed to the fact that approximately 85% of the nitrogen in EH was in the form of oligopeptides. The results indicate that pancreatic enzymes are not required for the terminal stages of protein digestion and suggest that enzymatic-ally hydrolyzed proteins are utilized more efficiently than mixtures of amino acids in the absence of exocrine pancreatic function. J. Nutr. 104: 793-801, 1974 The results of recent studies in man patients with cystinuria and Hartnup dissuggest that the end-product of protein di-ease, two inherited diseases in which the gestion within the intestinal lumen is a mix-absorptive mechanisms for certain dietary ture consisting primarily of oligopeptides essential amino acids in the free form are with lesser amounts of free amino acids greatly impaired, the ability to absorb es-(1, 2). Although the terminal events in-sential amino acids in the form of peptides volved in transporting the peptides into is considered to be important for survival the enterocytes are not fully understood, (9-11). there is direct evidence from human There is now evidence indicating that studies indicating that hydroxyproline pep-defects in amino acid absorption may be tides ( 3 ) and glycylglycine ( 4 ) are taken found in association with other clinical conup from the gut lumen intact and are trans-ditions. Thus, DiMagno et al.1 have shown ported as such to the portal blood. While that there is a marked impairment in the the amount of peptide material actually ability of patients with nontropical sprue entering the portal blood is not large, these to absorb mixtures of essential amino acids, findings do support the contention that Adibì and Allen (12) reported a reduction some peptides are absorbed from the in-jn the rates of essential amino acid absorptestinal lumen intact (5-8)