Fast digestive, leucine‐rich, soluble milk proteins improve muscle protein anabolism, and mitochondrial function in undernourished old rats

• Published in: Molecular nutrition & food research Vol. 61; no. 11
• Main Authors: Salles, Jérôme, Chanet, Audrey, Berry, Alexandre, Giraudet, Christophe, Patrac, Véronique, Domingues‐Faria, Carla, Rocher, Christophe, Guillet, Christelle, Denis, Philippe, Pouyet, Corinne, Bonhomme, Cécile, Ruyet, Pascale, Rolland, Yves, Boirie, Yves, Walrand, Stéphane
• Format: Journal Article
• Language: English
• Published: Germany Wiley Subscription Services, Inc 01.11.2017; Wiley-VCH Verlag
• Subjects: Activation; Animals; Biomarkers - blood; Biomarkers - metabolism; Body fat; Body weight; Casein; Diet; Dietary Supplements; Digestion; Elder Nutritional Physiological Phenomena; Energy intake; Energy management; Energy Metabolism; Leucine; Life Sciences; Magnetic Resonance Imaging; Male; Malnutrition; Malnutrition - diagnostic imaging; Malnutrition - diet therapy; Malnutrition - metabolism; Metabolism; Milk; Milk Proteins - chemistry; Milk Proteins - metabolism; Milk Proteins - therapeutic use; Mitochondria; Mitochondria, Muscle - enzymology; Mitochondria, Muscle - metabolism; mRNA; Muscle Development; Muscle Proteins - genetics; Muscle Proteins - metabolism; Muscle, Skeletal - diagnostic imaging; Muscle, Skeletal - metabolism; Old rats; Patients; Protein biosynthesis; Protein metabolism; Protein synthesis; Protein turnover; Proteins; Proteolysis; Random Allocation; Rats; Rats, Wistar; Refeeding; Rodents; Skeletal muscle; SKP Cullin F-Box Protein Ligases - genetics; SKP Cullin F-Box Protein Ligases - metabolism; Solubility; Soluble milk proteins; TOR protein; Tripartite Motif Proteins - genetics; Tripartite Motif Proteins - metabolism; Ubiquitin-Protein Ligases - genetics; Ubiquitin-Protein Ligases - metabolism; Valine; Whole Body Imaging; Refeeding; Malnutrition; Old rats; Skeletal muscle; Soluble milk proteins; protéine de lait; protéine musculaire; old rats; senior citizens; nutritional deficiency; personne âgée; protéine soluble; anabolism; métabolisme énergétique; anabolisme; malnutrition; refeeding; rat agé; soluble milk proteins; skeletal muscle
• ISSN: 1613-4125; 1613-4133
• DOI: 10.1002/mnfr.201700287

Scope One strategy to manage malnutrition in older patients is to increase protein and energy intake. Here, we evaluate the influence of protein quality during refeeding on improvement in muscle protein and energy metabolism. Methods and results Twenty‐month‐old male rats (n = 40) were fed 50% of their spontaneous intake for 12 weeks to induce malnutrition, then refed ad libitum with a standard diet enriched with casein or soluble milk proteins (22%) for 4 weeks. A 13C‐valine was infused to measure muscle protein synthesis and expression of MuRF1, and MAFbx was measured to evaluate muscle proteolysis. mTOR pathway activation and mitochondrial function were assessed in muscle. Malnutrition was associated with a decrease in body weight, fat mass, and lean mass, particularly muscle mass. Malnutrition decreased muscle mTOR pathway activation and protein FSR associated with increased MuRF1 mRNA levels, and decreased mitochondrial function. The refeeding period partially restored fat mass and lean mass. Unlike the casein diet, the soluble milk protein diet improved muscle protein metabolism and mitochondrial function in old malnourished rats. Conclusions These results suggest that providing better‐quality proteins during refeeding may improve efficacy of renutrition in malnourished older patients. Malnutrition accelerates the age‐related loss of muscle mass and function. One of the nutritional strategies to manage malnutrition in older patients is to increase protein and energy intake. It is found that soluble milk proteins improved body composition and protein metabolism and mitochondrial function in muscle in old malnourished rats. These results suggest that providing better quality proteins during refeeding may improve muscle renewal and efficacy of renutrition in malnourished older patients.