title: Prolonged ingestion of prehydrolyzed whey protein induces little or no change in digestive enzymes, but decreases glutaminase activity in exercising rats.
abstract: Because consumption of whey protein hydrolysates is on the increase, the possibility that prolonged ingestion of whey protein hydrolysates affect the digestive system of mammals has prompted us to evaluate the enzymatic activities of pepsin, leucine-aminopeptidase, chymotrypsin, trypsin, and glutaminase in male Wistar rats fed diets containing either a commercial whey isolate or a whey protein hydrolysate with medium degree of hydrolysis and to compare the results with those produced by physical training (sedentary, sedentary-exhausted, trained, and trained-exhausted) in the treadmill for 4 weeks. The enzymatic activities were determined by classical procedures in all groups. No effect due to the form of the whey protein in the diet was seen in the activities of pepsin, trypsin, chymotrypsin, and leucine-aminopeptidase. Training tended to increase the activity of glutaminase, but exhaustion promoted a decrease in the trained animals, and consumption of the hydrolysate decreased it even further. The results are consistent with the conclusion that chronic consumption of a whey protein hydrolysate brings little or no modification of the proteolytic digestive system and that the lowering of glutaminase activity may be associated with an antistress effect, counteracting the effect induced by training in the rat.
authors.affiliation: Food and Nutrition Department, School of Food Engineering and Center for Food Security Studies, University of Campinas, Campinas, São Paulo, Brazil.
authors.forename: Ana Cláudia C
authors.initials: AC
authors.lastname: Nery-Diez
authors.forename: Iara R
authors.initials: IR
authors.lastname: Carvalho
authors.forename: Jaime
authors.initials: J
authors.lastname: Amaya-Farfán
authors.forename: Maria Inés
authors.initials: MI
authors.lastname: Abecia-Soria
authors.forename: Célio K
authors.initials: CK
authors.lastname: Miyasaka
authors.forename: Clécio da S
authors.initials: Cda S
authors.lastname: Ferreira
mesh_terms: D000818:Animals; D004044:Dietary Proteins / Q000008:administration & dosage*; D004064:Digestive System / Q000737:chemistry / Q000201:enzymology* / Q000503:physiopathology; D015444:Exercise; D005972:Glutaminase / Q000032:analysis / Q000378:metabolism*; D006801:Humans; D008297:Male; D008894:Milk Proteins / Q000008:administration & dosage*; D023421:Models, Animal; D011492:Protein Hydrolysates / Q000008:administration & dosage*; D051381:Rats; D017208:Rats, Wistar; D000067816:Whey Proteins
chemical_list: D004044:Dietary Proteins; D008894:Milk Proteins; D011492:Protein Hydrolysates; D000067816:Whey Proteins; D005972:Glutaminase