The effect of food-derived bioactives peptides on myocardial function in swine after detraining, with and without high fat diet

Abstract

Introduction: This study explored whether α-lactalbumine (cysteine-rich protein), an antioxidant food compound from milk protein (isolat P), increased myocardial function and/or pro/antioxidant protein in swine. We measured the effect of isolat P after one month of detraining (following 12 months of moderate chronic training), with and without a high fat diet. Methods: Male Gottingen swine (n=34, 18-24 weeks) were randomly assigned into sedentary (S) or exercise groups (E), fed with standard (N) or deleterious (D) diets. Only the D diet groups were supplemented with isolat P (+ or -). 6 groups were designed (NS-, NE-, DS-, DE-, DS+, DE+). Swine performed a treadmill training protocol that achieved 150 bpm for 60 min/day, 5 days/week for 12 weeks, and then detrained for 4 weeks. At the end of the program, myocardial tissues were analyzed for pro-oxydant NADPH oxydase (p47phox, p67phox) and eNOS expression by densitometry, as well as for antioxydant enzyme activities of SOD, CAT and GPx by spectrophotometry. Results: NADPH oxydase expression (p47phox only) (104.94±3.24 vs. 101.25±1.04 A.U., p 0.05). In DE- group eNOS expression is lower than in DS- (71.61±1.27 UA vs 77.33±2.90 UA, p<0.05). No modifications statistically observe for the others enzymes. DS+ group led to decreased expression of eNOS (DS- 77.33±2.90 AU vs. DS+: 71.24±2.7 AU, p<0.05) to reach a basal value, without modifying other enzymes. These results suggest an eNOS recoupling. Finally, in DE+ group, isolat P restored the basal activity and expression of enzymes eNOS, NADPHoxydase, SOD, CAT and GPx to similar values as in sedentary animal fed a standard diet (NS-). Conclusion: Addition of isolat P to high fat diet reverses eNOS decoupling induced by high fat diet. Isolat P may have an antioxidant role allowing antioxidant enzymes SOD, CAT and GPx to recover basal activity levels while NADPH oxydase increases with a high fat diet. After one month of detraining, the beneficial effects of chronic exercise had disappeared. Isolat P may slow down the detraining effect on eNOS but not upon antioxidant enzymes. Therefore, early isolat P association with exercise training may be an interesting preventive strategy against metabolic diseases.