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

Previous studies have shown that hydrolyzed proteins exhibit antioxidant properties and may confer physical and physiological advantages when consumed by the exercising rat. The purpose of this study was to compare the effects of feeding either intact (I) and partly hydrolyzed (H) milk whey proteins on gastrocnemial DNA contents and protein metabolism in exercising Wistar rats. Protein synthesis and degradation, protein and DNA contents, and concentration of the serum insulin-like growth factor-1 (IGF1) were determined in six experimental groups according to the type of protein consumed [casein (C), whey protein isolate (I), hydrolyzed whey protein (H) and level of physical activity (sedentary (S) and trained (T)]. H produced significantly lower rates of protein synthesis and degradation and DNA contents in the gastrocnemius, while no differences were observed in the total muscle protein content and serum levels of IGF1. These results indicate that consumption of prehydrolyzed whey protein alters muscle metabolism resulting in less DNA, but maintains the muscle protein levels constant and sustain or improves physical performance, compared to the unhydrolyzed protein.Keywords: Dietary protein, hydrolyzed whey protein, peptides in muscle metabolism, phenylalanine, tyrosine, physical activityAfrican Journal of Biotechnology Vol. 12(16), pp. 2058-206

Effects of exercise and leucine diet suplementation on protein and carbohydrate metabolism in Walker 256 tumor-bearing rats

Orientador: Maria Cristina Gomes MarcondesTese (doutorado) - Universidade Estadual de Campinas, Instituto de BiologiaResumo: A intensa mobilização de substratos dos tecidos da carcaça do hospedeiro, em função do crescimento neoplásico, promove no organismo o estado caracterizado como caquexia. Presente na maioria dos pacientes com câncer, a caquexia promove intensa perda involuntária de peso decorrente, preferencialmente, da depleção da proteína muscular em função do aumento da degradação e/ou da diminuição da síntese protéica, culminando na redução da qualidade e expectativa de vida. Sabendo-se que a leucina (BCAA) é utilizada como fonte energética pelo músculo esquelético, podendo ser transaminada e oxidada para produzir acetil-CoA, caracterizada, também, como precursora da gliconeogênese, a partir da sua degradação e formação de alanina no músculo e age, principalmente, como sinalizadora celular e que o exercício físico promove aumento do consumo de glicose, diminuindo assim os níveis de glicose e insulina circulantes, conseqüentemente, reduzindo a oferta desse substrato às células tumorais. Temos por principal interesse minimizar as alterações metabólicas do tecido hospedeiro frente ao crescimento do carcinossarcoma de Walker associado ao exercício físico aeróbio de intensidade leve a moderada e suplementação nutricional de leucina, avaliando o metabolismo protéico, através de analise do processo de síntese e catabolismo protéico, e o metabolismo glicídico, analisando-se a via glicolítica e receptor de glicose muscular, bem como a concentração sérica de citocinas, em ratos Wistar. Desse modo nossos resultados verificamos: 1) Diminuição do ganho de peso corpóreo após o implante tumoral. 2) Diminuição da síntese e aumento da degradação protéica muscular acompanhada com menor conteúdo de proteína e expressão de miosina. 3) Consequente, aumento da expressão das subunidades ubiquitina-proteossomo. 4) Aumento das citocinas pró-inflamatórias. 5) Redução da concentração sérica de glicose, insulina e aumento de glucagon. 6) Redução da expressão gênica do transportador de glicose muscular, Glut-4. 7) Diminuição do diâmetro da fibra muscular esquelética. Já a suplementação nutricional com leucina e/ou exercício físico, a longo prazo, promove nos animais com tumor: 1) Melhora no ganho de peso corpóreo, com redução do peso tumoral em alguns grupos. 2) Diminui a degradação muscular esquelética, associada a maior expressão de miosina muscular. 3) Melhora a concentração de citocinas próinflamatórias. 4) Melhora a expressão gênica de transportador de glicose muscular, Glut- 4. 5) Melhora, também, o diâmetro da fibra muscularAbstract: The intense nutrients mobilization of host tissues, due to neoplastic growth, leads to host cachexia state. Most cancer patients have cachexia, which is characterized by involuntary weight loss through increase in protein muscle depletion and decrease in protein synthesis process. In these cases, there is reduction in quality and life expectancy. Leucine (BCAA) is used as an energy source by skeletal muscle, precursor of gluconeogenesis or acts as cell signaling and physical exercise promotes increased consumption of glucose, reducing the levels of circulating glucose and insulin, providing less supply of substrate to tumour. In this work, our main interests were to minimize the metabolic alterations in tumor-bearing host associated with nutritional supplementation of leucine and moderate aerobic exercise during Walker 256 tumour growth and whether this association could avoid or protect muscular depletion, analyzing protein metabolism through protein synthesis and catabolism process, and muscle carbohydrate metabolism through analysis of glucose metabolism, by evaluating glycolytic pathway and muscle glucose receptor in rats. Thus our results found: 1) Decrease in body weight gain after tumor implantation. 2) Decreased synthesis and increased muscle protein degradation accompanied with lower protein content and expression of myosin. 3) Accordingly, increased expression of ubiquitin-subunits proteosome. 4) Increase of pro-inflammatory cytokines. 5) Reduction of serum glucose, insulin and glucagon increase. 6) Reduction of gene expression of muscle glucose transporter, Glut-4. 7) Decrease in diameter of skeletal muscle fibers. Since dietary supplementation with leucine and / or exercise in the long run, promote the animals with tumor: 1) Improvement in body weight gain, reducing the tumor burden in some groups. 2) Decrease in skeletal muscle degradation, associated with increased expression of muscle myosin. 3) Improve the concentration of pro-inflammatory cytokines. 4) Improve the gene expression of muscle glucose transporter, Glut-4. 5) It also improves the diameter of muscle fiberDoutoradoFisiologiaDoutor em Biologia Funcional e Molecula

Light Aerobic Physical Exercise In Combination With Leucine And/or Glutamine-rich Diet Can Improve The Body Composition And Muscle Protein Metabolism In Young Tumor-bearing Rats.

Nutritional supplementation with some amino acids may influence host's responses and also certain mechanism involved in tumor progression. It is known that exercise influences body weight and muscle composition. Previous findings from our group have shown that leucine has beneficial effects on protein composition in cachectic rat model as the Walker 256 tumor. The main purpose of this study was to analyze the effects of light exercise and leucine and/or glutamine-rich diet in body composition and skeletal muscle protein synthesis and degradation in young tumor-bearing rats. Walker tumor-bearing rats were subjected to light aerobic exercise (swimming 30 min/day) and fed a leucine-rich (3%) and/or glutamine-rich (4%) diet for 10 days and compared to healthy young rats. The carcasses were analyzed as total water and fat body content and lean body mass. The gastrocnemious muscles were isolated and used for determination of total protein synthesis and degradation. The chemical body composition changed with tumor growth, increasing body water and reducing body fat content and total body nitrogen. After tumor growth, the muscle protein metabolism was impaired, showing that the muscle protein synthesis was also reduced and the protein degradation process was increased in the gastrocnemius muscle of exercised rats. Although short-term exercise (10 days) alone did not produce beneficial effects that would reduce tumor damage, host protein metabolism was improved when exercise was combined with a leucine-rich diet. Only total carcass nitrogen and protein were recovered by a glutamine-rich diet. Exercise, in combination with an amino acid-rich diet, in particular, leucine, had effects beyond reducing tumoral weight such as improving protein turnover and carcass nitrogen content in the tumor-bearing host.68493-50

Leucine Modulates The Effect Of Walker Factor, A Proteolysis-inducing Factor-like Protein From Walker Tumours, On Gene Expression And Cellular Activity In C2c12 Myotubes.

Cancer-cachexia causes severe weight loss, particularly from the wasting of skeletal muscle, which occurs due to increased protein catabolism and/or decreased protein synthesis. The muscle protein degradation observed in cancer patients is mediated by a specific cytokine, proteolysis-inducing factor (PIF), which is produced by the tumour. This protein increases the ubiquitin-proteasome pathway activity, and the synthesis of muscle protein in these patients can be affected by several factors, including nutrient-related signalling. Some nutrients, such as leucine, can decrease the ubiquitin-proteasome pathway activity and increase the skeletal muscle protein content in cachectic animals. In this study, we investigated the effects of leucine on cell viability, morphology, functional proteasome activity, enzymatic activity, and protein synthesis and degradation in C2C12 myotubes exposed to the proteolysis-inducing factor (PIF)-like protein purified from Walker tumour-bearing rats. Walker factor (WF) had no cytotoxic effects on myotube cells and morphological characteristics were not altered in the presence of WF and/or leucine. However, increased alkaline phosphatase activity was observed. At higher WF concentrations, chymotrypsin-like activity, cathepsin B activity and 20S proteasome gene expression increased. Treating myotubes with leucine before exposure to WF causes leads to a decrease in proteasome activity as well as the activity of chymotrypsin and cathepsin enzymes. Total protein synthesis decreased in WF-treated cells concomitantly as protein degradation increased. After leucine exposure, the observed effects of WF were minimal or even reverted in some cases. Taken together, these results suggest an important modulatory effect for leucine on the effects of WF in C2C12 myotube cells.64343-5

A leucine-rich diet and exercise affect the biomechanical characteristics of the digital flexor tendon in rats after nutritional recovery.

An increase in the capacity of athletic performance depends on adequate nutrition, which ensures optimal function of the musculoskeletal system, including tendon stability. However, little is known about the status of tendons and extracellular matrix modifications during malnutrition and nutritional recovery when leucine is used in response to exercise conditioning. The purpose of this study was to evaluate the collagen content and biomechanical aspects of the deep digital flexor tendon (DDFT) in malnourished rats submitted to nutritional recovery (control diet or leucine-rich diet) and aerobic physical activity. After 60 days of undernourishment (6% protein diet), the malnourished rats were subsequently nutritionally recovered with a control diet or leucine-rich diet and trained or not (swimming, without overload) for 5 weeks. The biomechanical analysis and quantification of hydroxyproline were assessed in the DDFT in all experimental groups. The leucine-rich diet increased hydroxyproline content in the tension region, independently of the training. In the compression region, hydroxyproline content was higher in the malnourished and leucine-trained groups. Biomechanical analysis showed a lower load in the malnourished and all-trained groups. The lowest stress was observed with control-trained animals. The nutritional-recovered groups showed higher strain values corresponding to control group, while the lowest values were observed in malnourished and trained groups. The results suggest that a leucine-rich diet stimulates collagen synthesis of the DDFT, especially when in combination with physical exercise, and seems to determine the increase of resistance and the biomechanical characteristics of tendons.An increase in the capacity of athletic performance depends on adequate nutrition, which ensures optimal function of the musculoskeletal system, including tendon stability. However, little is known about the status of tendons and extracellular matrix modifications during malnutrition and nutritional recovery when leucine is used in response to exercise conditioning. The purpose of this study was to evaluate the collagen content and biomechanical aspects of the deep digital flexor tendon (DDFT) in malnourished rats submitted to nutritional recovery (control diet or leucine-rich diet) and aerobic physical activity. After 60 days of undernourishment (6% protein diet), the malnourished rats were subsequently nutritionally recovered with a control diet or leucine-rich diet and trained or not (swimming, without overload) for 5 weeks. The biomechanical analysis and quantification of hydroxyproline were assessed in the DDFT in all experimental groups. The leucine-rich diet increased hydroxyproline content in the tension region, independently of the training. In the compression region, hydroxyproline content was higher in the malnourished and leucine-trained groups. Biomechanical analysis showed a lower load in the malnourished and all-trained groups. The lowest stress was observed with control-trained animals. The nutritional-recovered groups showed higher strain values corresponding to control group, while the lowest values were observed in malnourished and trained groups. The results suggest that a leucine-rich diet stimulates collagen synthesis of the DDFT, especially when in combination with physical exercise, and seems to determine the increase of resistance and the biomechanical characteristics of tendons

A Leucine-rich Diet And Exercise Affect The Biomechanical Characteristics Of The Digital Flexor Tendon In Rats After Nutritional Recovery.

An increase in the capacity of athletic performance depends on adequate nutrition, which ensures optimal function of the musculoskeletal system, including tendon stability. However, little is known about the status of tendons and extracellular matrix modifications during malnutrition and nutritional recovery when leucine is used in response to exercise conditioning. The purpose of this study was to evaluate the collagen content and biomechanical aspects of the deep digital flexor tendon (DDFT) in malnourished rats submitted to nutritional recovery (control diet or leucine-rich diet) and aerobic physical activity. After 60 days of undernourishment (6% protein diet), the malnourished rats were subsequently nutritionally recovered with a control diet or leucine-rich diet and trained or not (swimming, without overload) for 5 weeks. The biomechanical analysis and quantification of hydroxyproline were assessed in the DDFT in all experimental groups. The leucine-rich diet increased hydroxyproline content in the tension region, independently of the training. In the compression region, hydroxyproline content was higher in the malnourished and leucine-trained groups. Biomechanical analysis showed a lower load in the malnourished and all-trained groups. The lowest stress was observed with control-trained animals. The nutritional-recovered groups showed higher strain values corresponding to control group, while the lowest values were observed in malnourished and trained groups. The results suggest that a leucine-rich diet stimulates collagen synthesis of the DDFT, especially when in combination with physical exercise, and seems to determine the increase of resistance and the biomechanical characteristics of tendons.42329-3