Arginine and Lysine Supplementation Potentiates the Beneficial ß-Hydroxy ß-Methyl Butyrate (HMB) Effects on Skeletal Muscle in a Rat Model of Diabetes.

Skeletal muscle is the key tissue for maintaining protein and glucose homeostasis, having a profound impact on the development of diabetes. Diabetes causes deleterious changes in terms of loss of muscle mass, which will contribute to reduced glucose uptake and therefore progression of the disease. Nutritional approaches in diabetes have been directed to increase muscle glucose uptake, and improving protein turnover has been at least partially an oversight. In muscle, ß-hydroxy ß-methyl butyrate (HMB) promotes net protein synthesis, while arginine and lysine increase glucose uptake, albeit their effects on promoting protein synthesis are limited. This study evaluates if the combination of HMB, lysine, and arginine could prevent the loss of muscle mass and function, reducing the progression of diabetes. Therefore, the combination of these ingredients was tested in vitro and in vivo. In muscle cell cultures, the supplementation enhances glucose uptake and net protein synthesis due to an increase in the amount of GLUT4 transporter and stimulation of the insulin-dependent signaling pathway involving IRS-1 and Akt. In vivo, using a rat model of diabetes, the supplementation increases lean body mass and insulin sensitivity and decreases blood glucose and serum glycosylated hemoglobin. In treated animals, an increase in GLUT4, creatine kinase, and Akt phosphorylation was detected, demonstrating the synergic effects of the three ingredients. Our findings showed that nutritional formulations based on the combination of HMB, lysine, and arginine are effective, not only to control blood glucose levels but also to prevent skeletal muscle atrophy associated with the progression of diabetes.

Influencia del suplemento con inulina enriquecida con fructooligosacáridos sobre el contenido y la densidad mineral ósea tras el parto y la lactación en ratas / Influence of supplementation with oligofructose-enriched inulin on bone mineral content and density after delivery and lactation in rats

Introducción: la gestación y lactancia están relacionadas con pérdidas temporales en la densidad mineral ósea (DMO) materna. Una suplementación con calcio podría resultar beneficiosa para evitar la pérdida de masa ósea del esqueleto materno. Otros nutrientes como los prebióticos han sido identificados como responsables de un incremento en la absorción de minerales, pudiendo condicionar la mineralización ósea. Objetivo: estudiar el efecto de la suplementación de la dieta materna con el prebiótico inulina enriquecida con oligofructosa, durante la gestación y la lactancia sobre el contenido mineral óseo (CMO) y la DMO al final del periodo de lactancia. Métodos: las ratas gestantes fueron alimentadas con dieta estándar (grupo CC), dieta fortificada en calcio (grupo Ca) o enriquecida con el prebiótico inulina enriquecida con oligofructosa (grupo Pre) hasta el final del periodo de lactancia. Posteriormente se evaluó el CMO y DMO por absorciometría de rayos X (DEXA) y el pH del contenido cecal. Resultados: en términos generales, el grupo Pre presenta los mayores valores absolutos de CMO y DMO de entre los tres grupos, siendo en la tibia significativamente diferentes en los grupos CC y Pre frente al grupo Ca. El pH del contenido cecal del grupo Pre es signifi cativamente inferior al de los grupos CC y Ca. Conclusión: la suplementación con inulina enriquecida con oligofructosa, en condiciones nutricionales no deficientes en calcio, durante la gestación y la lactancia, ejerce una protección del esqueleto materno en las ratas y puede ser considerada como una estrategia nutricional para proteger la masa ósea materna en el periodo perinatal (AU)

Introduction: Pregnancy and lactation are related with temporary decreases in maternal bone mineral density (BMD). Calcium supplementation could be beneficial to prevent bone loss of maternal skeleton. Other nutrients, such as prebiotics have showed to produce an increase of the mineral absorption and therefore affecting bone mineralization. Objective: To study the effect of maternal diet supplementation with prebiotic oligofructose-enriched inulin during gestation and lactation on the maternal bone mineral content (BMC) and BMD at the end of lactation. Methods: Pregnant rats were fed with standard diet (CC group), calcium fortified diet (Ca group) or with prebiotic oligofructose-enriched inulin supplemented diet until the end of the lactation period. At weaning, bone mineral content (BMC) and BMD were determined by dual-energy X-ray absorptiometry and the pH of the cecal content was also determined. Results: In absolute terms, the highest BMD and BMC were found in the Pre group as compared with the other two groups being significant in the tibia when compared Pre group and CC group with Ca group. The pH of the cecal content in the Pre group was also significantly lower as compared with the other two groups. Conclusion: Prebiotic oligofructose-enriched inulin supplementation, in calcium no-deficient conditions, during gestation and lactation exerts a protection on maternal skeleton during pregnancy and lactation in the rats and could be considered as a plausible nutritional option for protecting maternal bone mass during these periods (AU)

Skeletal Muscle Regulates Metabolism via Interorgan Crosstalk: Roles in Health and Disease.

Skeletal muscle is recognized as vital to physical movement, posture, and breathing. In a less known but critically important role, muscle influences energy and protein metabolism throughout the body. Muscle is a primary site for glucose uptake and storage, and it is also a reservoir of amino acids stored as protein. Amino acids are released when supplies are needed elsewhere in the body. These conditions occur with acute and chronic diseases, which decrease dietary intake while increasing metabolic needs. Such metabolic shifts lead to the muscle loss associated with sarcopenia and cachexia, resulting in a variety of adverse health and economic consequences. With loss of skeletal muscle, protein and energy availability is lowered throughout the body. Muscle loss is associated with delayed recovery from illness, slowed wound healing, reduced resting metabolic rate, physical disability, poorer quality of life, and higher health care costs. These adverse effects can be combatted with exercise and nutrition. Studies suggest dietary protein and leucine or its metabolite ß-hydroxy ß-methylbutyrate (HMB) can improve muscle function, in turn improving functional performance. Considerable evidence shows that use of high-protein oral nutritional supplements (ONS) can help maintain and rebuild muscle mass and strength. We review muscle structure, function, and role in energy and protein balance. We discuss how disease- and age-related malnutrition hamper muscle accretion, ultimately causing whole-body deterioration. Finally, we describe how specialized nutrition and exercise can restore muscle mass, strength, and function, and ultimately reverse the negative health and economic outcomes associated with muscle loss.

Salacia oblonga extract increases glucose transporter 4-mediated glucose uptake in L6 rat myotubes: role of mangiferin.

BACKGROUND AND AIMS: To evaluate if the antidiabetic properties of Salacia oblonga extract are mediated not only by inhibiting intestinal alpha-glycosidases but also by enhancing glucose transport in muscle and adipose cells. METHODS: S. oblonga extract effects on 2-deoxy-D-glucose uptake were assayed in muscle L6-myotubes and 3T3-adipocytes. In L6-myotubes, the amount and translocation of glucose transporters were assayed. A fractionation of the extract was carried out to identify the active compounds. Furthermore, we analyzed the phosphorylation status of key components of signaling pathways that are involved in the molecular mechanisms regulating glucose uptake. RESULTS: S. oblonga extract increased 2-deoxy-D-glucose uptake by 50% in L6-myotubes and 3T3-adipocytes. In L6-myotubes, the extract increased up to a 100% the GLUT4 content, activating GLUT4 promoter transcription and its translocation to the plasma membrane. Mangiferin was identified as the bioactive compound. Furthermore, mangiferin effects were concomitant with the phosphorylation of 5'-AMP-activated protein kinase without the activation of PKB/Akt. The effect of mangiferin on 2-deoxy-D-glucose uptake was blocked by GW9662, an irreversible PPAR-gamma antagonist. CONCLUSIONS: S. oblonga extract and mangiferin may exert their antidiabetic effect by increasing GLUT4 expression and translocation in muscle cells. These effects are probably mediated through two independent pathways that are related to 5'-AMP-activated protein kinase and PPAR-gamma.

N-acetyl-L-glutamine, a liquid-stable source of glutamine, partially prevents changes in body weight and on intestinal immunity induced by protein energy malnutrition in pigs.

The goal of this study was to evaluate the preventive effect of free glutamine versus N-acetyl-L-glutamine, a liquid-stable source of glutamine, on gut damage induced by protein energy malnutrition in pigs. Healthy pigs (n = 6) were fed a liquid formula for 30 days. Three subgroups of malnourished pigs (n = 6) received daily 20% of the food intake recorded in control group, supplemented with calcium caseinate, glutamine, or N-acetyl-L-glutamine. Body weight was recorded, and small intestinal samples were evaluated for biochemical and immunologic parameters. Suppression in body weight gain was significantly lower in pigs fed with N-acetyl-L-glutamine than in the rest of malnourished pigs. Total number of lymphocytes, CD21+ B cells and CD4+ T cells in ileal Peyer patches were not significantly different in malnourished pigs fed with N-acetyl-L-glutamine and in healthy pigs. In conclusion, N-acetyl-L-glutamine has a moderate protective effect, partially preventing changes induced by protein energy malnutrition.