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.

Prehydrolyzed dietary protein reduces gastrocnemial DNA without impairing physical capacity in the rat

“…The various advantages pointed out for the whey protein hydrolyzates are consistent also with a possible beneficial effect to the experimental animal, as has been the case of physical performance in rats undergoing endurance exercise (Morifuji et al, 2009;Pimenta et al, 2005) and promoting the synthesis of glycogen (Morifuji et al, 2009). Nery-Diez et al (2010 additionally have suggested an anti-stress effect associated with the consumption of the whey protein hydrolyzate in rats undergoing endurance exercise.…”

“…Hydrolyzing the protein alone could in itself alter the biological function of the protein, thus affecting metabolism (Meisel, 1998). It has been suggested, for instance, that the mere change of the physicochemical form in which the protein is presented to the animal suffices to influence the general metabolism, apparently as a result of the various peptides that are generated during partial enzymatic hydrolysis of the whey proteins (Morifuji et al, 2009;Nery-Diez et al, 2010;Faria et al, 2012). Alteration in glycogen metabolism has been perhaps the most often reported positive feature resulting from substituting a whey protein hydrolyzate for the native Grouping of animals by type of diet and physical activity.…”

Whey Protein Hydrolysate Increases Translocation of GLUT-4 to the Plasma Membrane Independent of Insulin in Wistar Rats

“…Based on previous findings by the present [3], [7], [8] and other [10], [23] authors clearly showing that the consumption of WP and WPH raised muscle and hepatic glycogen levels, the objective of the present study was to verify the effect that the consumption of WP and WPH had on the translocation of the glucose transporters GLUT-4 and GLUT-1 to the plasma membrane (PM), as compared to rats fed a standard diet (AIN93-G) with casein as the protein source. The results showed clearly that the consumption of WP and WPH increased the translocation of GLUT-4 (Figure 2A) when compared to the casein-fed animals, whereas GLUT-1 (Figure 2B) was not responsive to the different proteins.…”

“…Different food proteins may affect muscle metabolism in different fashions, as shown when the effects of whey proteins (WP) are compared to those of casein (CAS) [1]–[3]. One difference between WP and CAS is that WP stimulates an increase of fatty acid synthesis in the muscle accompanied by a concomitant decrease in fatty acid synthesis in the liver, considered to be a positive effect on lipid metabolism [4].…”

“…Hydrolysis of the protein alone could alter the biological function of the protein, thus affecting the metabolism [5]. For example, it has been suggested that a slight change in the physicochemical form of the protein when presented to the animal can be enough to influence the general metabolism, apparently as a result of the various peptides that are generated during partial enzymatic hydrolysis of whey proteins (WPH) [3], [6]–[8]. The bioactive peptides present in WPH might be capable of reducing the levels of creatine kinase in soccer players [9].…”