Abstract
ABSTRACTBackground: Several physiologically beneficial effects of consuming a whey protein hydrolysate (WPH) have been attributed to the greater availability of bioactive peptides.Aims: The aim was to investigate the effect of four branched-chain amino acid- (BCAA-)containing dipeptides, present in WPH, on immune modulation, stimulation of HSP expression, muscle protein synthesis, glycogen content, satiety signals and the impact of these peptides on the plasma free amino acid profiles.Methods: The animals were divided in groups: control (rest, without gavage), vehicle (water), L-isoleucyl-L-leucine (lle-Leu), L-leucyl-L-isoleucine (Leu-lle), L-valyl-Lleucine (Val-Leu), L-leucyl-L-valine (Leu-Val) and WPH. All animals were submitted to acute exercise, except for control.Results: lle-Leu stimulated immune response, hepatic and muscle glycogen and HSP60 expression, whereas Leu-Val enhanced HSP90 expression. All dipeptides reduced glucagon-like peptide-1 and glucose-dependent insulinotropic polypeptide, no changes were observed on leptin. All peptides inhibited NF-kB expression. The plasma amino acid time-course showed peptide-specific and isomer-specific metabolic features, including increases of the BCAAs.Conclusion: The data indicate that lle-Leu was effective to attenuate immune-suppression exercise-induced, promoted glycogen content and stimulated anti-stress effect (HSP). Furthermore, Leu-Val increased HSP90, p-4EBP1, p-mTOR and p-AMPK expression. The data suggest the involvement of these peptides in various beneficial functions of WPH consumption.
Highlights
Whey proteins (WPs) are known to be functional for promoting the improvement of several biological responses that include cytoprotective effects mediated by the enhancement of heat shock protein (HSP) expression, promotion of glycogen content, stimulation of muscle protein synthesis, modulation of the immune response and improvement of satiety [1,2,3,4,5,6]
Our present results indicate that dipeptide Leu-Val may be involved in the whey protein hydrolysate (WPH) capacity to induce HSP90 expression, while only lle-Leu may enhance the exercise-induced HSP60 expression
Our results suggest that none of the branched-chain amino acid- (BCAA-)containing dipeptides are potential contributors to the alleged satiety effect of whey if we considered the effect on glucose-dependent insulinotropic polypeptide (GIP) and glucagon-like peptide-1 (GLP-1)
Summary
Whey proteins (WPs) are known to be functional for promoting the improvement of several biological responses that include cytoprotective effects mediated by the enhancement of heat shock protein (HSP) expression, promotion of glycogen content, stimulation of muscle protein synthesis, modulation of the immune response and improvement of satiety [1,2,3,4,5,6]. WPs become rich sources of bioactive peptides, including branched-chain amino acid- (BCAA)-containing dipeptides [8], which can act as cell-signaling molecules capable of modulating physiologic functions reaching cells and tissues [9]. Aims: The aim was to investigate the effect of four branched-chain amino acid- (BCAA-)containing dipeptides, present in WPH, on immune modulation, stimulation of HSP expression, muscle protein synthesis, glycogen content, satiety signals and the impact of these peptides on the plasma free amino acid profiles
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