Beta-hydroxy-beta-methyl butyrate (HMB) is a unique product of leucine catabolism with positive effects on protein balance. We have examined the effects of HMB (200 mg/kg/day via osmotic pump for 7 days) on rats with diabetes induced by streptozotocin (STZ, 100 mg/kg intraperitoneally). STZ induced severe diabetes associated with muscle wasting, decreased ATP in the liver, and increased α-ketoglutarate in muscles. In plasma, liver, and muscles increased branched-chain amino acids (BCAAs; valine, isoleucine, and leucine) and decreased serine. The decreases in mass and protein content of muscles and increases in BCAA concentration were more pronounced in extensor digitorum longus (fast-twitch muscle) than in soleus muscle (slow-twitch muscle). HMB infusion to STZ-treated animals increased glycemia and serine in the liver, decreased BCAAs in plasma and muscles, and decreased ATP in the liver and muscles. The effects of HMB on the weight and protein content of tissues were nonsignificant. We concluded that fast-twitch muscles are more sensitive to STZ than slow-twitch muscles and that HMB administration to STZ-treated rats has dual effects. Adjustments of BCAA concentrations in plasma and muscles and serine in the liver can be considered beneficial, whereas the increased glycemia and decreased ATP concentrations in the liver and muscles are detrimental.
- MeSH
- aminokyseliny aplikace a dávkování farmakologie MeSH
- diabetes mellitus 1. typu chemicky indukované farmakoterapie metabolismus MeSH
- injekce intraperitoneální MeSH
- injekce subkutánní MeSH
- játra účinky léků metabolismus MeSH
- kosterní svaly účinky léků metabolismus MeSH
- krysa rodu rattus MeSH
- potkani Wistar MeSH
- streptozocin aplikace a dávkování MeSH
- valeráty aplikace a dávkování farmakologie MeSH
- zvířata MeSH
- Check Tag
- krysa rodu rattus MeSH
- mužské pohlaví MeSH
- zvířata MeSH
- Publikační typ
- časopisecké články MeSH
- práce podpořená grantem MeSH
Both regular exercise training and beta-hydroxy-beta-methylbutyrate (HMB) supplementation are shown as effective treatments to delay or reverse frailty and reduce cognitive impairment in older people. However, there is very little evidence on the true benefits of combining both strategies. The aim of this meta-analysis was to quantify the effects of exercise in addition to HMB supplementation, on physical and cognitive health in older adults. Data from 10 randomized controlled trials (RCTs) investigating the effect of HMB supplementation and physical function in adults aged 50 years or older were analyzed, involving 384 participants. Results showed that HMB supplementation in addition to physical exercise has no or fairly low impact in improving body composition, muscle strength, or physical performance in adults aged 50 to 80 years, compared to exercise alone. There is a gap of knowledge on the beneficial effects of HMB combined with exercise to preserve cognitive functions in aging and age-related neurodegenerative diseases. Future RCTs are needed to refine treatment choices combining HMB and exercises for older people in particular populations, ages, and health status. Specifically, interventions in older adults aged 80 years or older, with cognitive impairment, frailty, or limited mobility are required.
- MeSH
- cvičení fyziologie MeSH
- lidé MeSH
- potravní doplňky * MeSH
- stárnutí * MeSH
- valeráty aplikace a dávkování farmakologie MeSH
- Check Tag
- lidé MeSH
- Publikační typ
- časopisecké články MeSH
- metaanalýza MeSH
- systematický přehled MeSH
Beta-hydroxy-beta-methylbutyrate (HMB) is a leucine metabolite with protein anabolic effects. We examined the effects of an HMB-enriched diet in healthy rats and rats with liver cirrhosis induced by multiple doses of carbon tetrachloride (CCl4). HMB increased branched-chain amino acids (BCAAs; valine, leucine and isoleucine) in blood and BCAA and ATP in muscles of healthy animals. The effect on muscle mass and protein content was insignificant. In CCl4-treated animals alterations characteristic of liver cirrhosis were found with decreased ratio of the BCAA to aromatic amino acids in blood and lower muscle mass and ATP content when compared with controls. In CCl4-treated animals consuming HMB, we observed higher mortality, lower body weight, higher BCAA levels in blood plasma, higher ATP content in muscles, and lower ATP content and higher cathepsin B and L activities in the liver when compared with CCl4-treated animals without HMB. We conclude that (1) HMB supplementation has a positive effect on muscle mitochondrial function and enhances BCAA concentrations in healthy animals and (2) the effects of HMB on the course of liver cirrhosis in CCl4-treated rats are detrimental. Further studies examining the effects of HMB in other models of hepatic injury are needed to determine pros and cons of HMB in the treatment of subjects with liver cirrhosis.
- MeSH
- chlorid uhličitý metabolismus MeSH
- jaterní cirhóza metabolismus MeSH
- játra účinky léků metabolismus MeSH
- kosterní svaly účinky léků metabolismus MeSH
- leucin metabolismus MeSH
- potkani Wistar MeSH
- potravní doplňky MeSH
- valeráty farmakologie MeSH
- větvené aminokyseliny metabolismus MeSH
- zvířata MeSH
- Check Tag
- zvířata MeSH
- Publikační typ
- časopisecké články MeSH
- práce podpořená grantem MeSH
Beta-hydroxy-beta-methylbutyrate (HMB) is a metabolite of the essential amino acid leucine that has been reported to have anabolic effects on protein metabolism. The aims of this article were to summarize the results of studies of the effects of HMB on skeletal muscle and to examine the evidence for the rationale to use HMB as a nutritional supplement to exert beneficial effects on muscle mass and function in various conditions of health and disease. The data presented here indicate that the beneficial effects of HMB have been well characterized in strength-power and endurance exercise. HMB attenuates exercise-induced muscle damage and enhances muscle hypertrophy and strength, aerobic performance, resistance to fatigue, and regenerative capacity. HMB is particularly effective in untrained individuals who are exposed to strenuous exercise and in trained individuals who are exposed to periods of high physical stress. The low effectiveness of HMB in strength-trained athletes could be due to the suppression of the proteolysis that is induced by the adaptation to training, which may blunt the effects of HMB. Studies performed with older people have demonstrated that HMB can attenuate the development of sarcopenia in elderly subjects and that the optimal effects of HMB on muscle growth and strength occur when it is combined with exercise. Studies performed under in vitro conditions and in various animal models suggest that HMB may be effective in treatment of muscle wasting in various forms of cachexia. However, there are few clinical reports of the effects of HMB on muscle wasting in cachexia; in addition, most of these studies evaluated the therapeutic potential of combinations of various agents. Therefore, it has not been possible to determine whether HMB was effective or if there was a synergistic effect. Although most of the endogenous HMB is produced in the liver, there are no reports regarding the levels and the effects of HMB supplementation in subjects with liver disease. Several studies have suggested that anabolic effects of HMB supplementation on skeletal muscle do not occur in healthy, non-exercising subjects. It is concluded that (i) HMB may be applied to enhance increases in the mass and strength of skeletal muscles in subjects who exercise and in the elderly and (ii) studies examining the effects of HMB administered alone are needed to obtain conclusions regarding the specific effectiveness in attenuating muscle wasting in various muscle-wasting disorders.
- MeSH
- kachexie dietoterapie patofyziologie MeSH
- kosterní svaly účinky léků fyziologie MeSH
- lidé MeSH
- potravní doplňky MeSH
- sarkopenie dietoterapie patofyziologie MeSH
- svalová atrofie dietoterapie patofyziologie MeSH
- svalová síla účinky léků MeSH
- syndrom chřadnutí dietoterapie patofyziologie MeSH
- valeráty aplikace a dávkování farmakologie MeSH
- zdraví MeSH
- zvířata MeSH
- Check Tag
- lidé MeSH
- zvířata MeSH
- Publikační typ
- časopisecké články MeSH
- přehledy MeSH
Beta-hydroxy-beta-methylbutyrate (HMB) is a leucine metabolite with protein anabolic effect. The aim of the study was to examine the role of exogenous HMB on leucine and protein metabolism in whole body and selected tissues. Rats were administered by HMB (0.1 g/kg b.w.) or by saline. The parameters of whole-body protein metabolism were evaluated 24 h later using L-[1-14C]leucine and L-[3,4,5-3H]phenylalanine. Changes in proteasome dependent proteolysis and protein synthesis were determined according the "chymotrypsin-like" enzyme activity and labeled leucine and phenylalanine incorporation into the protein. A decrease in leucine clearance and whole-body protein turnover (i.e., a decrease in whole-body proteolysis and protein synthesis) was observed in HMB treated rats. Proteasome-dependent proteolysis decreased significantly in skeletal muscle, changes in heart, liver, jejunum, colon, kidney, and spleen were insignificant. Decrease in protein synthesis was observed in the heart, colon, kidney, and spleen, while an increase was observed in the liver. There were no significant changes in leucine oxidation. We conclude that protein anabolic effect of HMB in skeletal muscle is related to inhibition of proteolysis in proteasome. Alterations in protein synthesis in visceral tissues may affect several important functions and the metabolic status of the whole body.
- MeSH
- financování organizované MeSH
- játra metabolismus účinky léků MeSH
- kosterní svaly metabolismus účinky léků MeSH
- krysa rodu rattus MeSH
- ledviny metabolismus účinky léků MeSH
- myokard metabolismus MeSH
- N-acetyltransferasa aminokyselin metabolismus MeSH
- potkani Wistar MeSH
- proteiny metabolismus MeSH
- slezina metabolismus účinky léků MeSH
- srdce účinky léků MeSH
- střeva metabolismus účinky léků MeSH
- valeráty farmakologie MeSH
- zvířata MeSH
- Check Tag
- krysa rodu rattus MeSH
- mužské pohlaví MeSH
- zvířata MeSH
Beta-hydroxy-beta-metylbutyrát (HMB) je metabolitem leucinu, jenž vykazuje antikatabolické účinky a příznivě ovlivňuje imunitní systém. Mechanismus účinku nebyl dosud zcela objasněn. HMB může sloužit jako zdroj pro syntézu cholesterolu, zřejmě zasahuje také do ubikvitin-proteazomového proteolytického systému. HMB je užíván jako potravinový doplněk při silovém tréninku, zejména pro nárůst síly a množství netukové tkáně. V posledních letech se také testuje jako součást terapie kachexie různé etiologie (např. nádory, AIDS).
Beta-hydroxy-beta-methylbutyrate (HMB) is the leucine metabolite, which shows anti-catabolic effect and beneficially affects the immune system. The mechanism of action is still not fully understood. HMB may serve as the source for cholesterol synthesis and it probably affects the ubiquitin-proteasome proteolytic system. HMB is used as a dietary supplement during resistance-training, especially for increase of power and non-fat body mass. It has been also tested in recent years as a part of cachexia treatment (cancer, AIDS, etc.).
- MeSH
- arginin terapeutické užití MeSH
- glutamin terapeutické užití MeSH
- kachexie MeSH
- klinické zkoušky jako téma MeSH
- kosterní svaly MeSH
- lidé MeSH
- potravní doplňky MeSH
- proteasomový endopeptidasový komplex účinky léků MeSH
- valeráty farmakokinetika farmakologie terapeutické užití MeSH
- zvířata MeSH
- Check Tag
- lidé MeSH
- zvířata MeSH
- MeSH
- AMPA receptory antagonisté a inhibitory MeSH
- chování při pití účinky léků MeSH
- excitační aminokyseliny antagonisté a inhibitory farmakologie MeSH
- krysa rodu rattus MeSH
- mikroinjekce MeSH
- nucleus basalis Meynerti cytologie fyziologie MeSH
- valeráty farmakologie MeSH
- zvířata MeSH
- Check Tag
- krysa rodu rattus MeSH
- zvířata MeSH
- MeSH
- akryláty farmakologie MeSH
- alkylační látky farmakologie chemická syntéza MeSH
- antimetabolity farmakologie MeSH
- antitumorózní látky farmakologie chemická syntéza MeSH
- benzoáty farmakologie MeSH
- brom farmakologie MeSH
- cytidin farmakologie MeSH
- fluor farmakologie MeSH
- hypoxanthiny farmakologie MeSH
- lidé MeSH
- pyrimidiny farmakologie MeSH
- sloučeniny dusíkatého yperitu farmakologie MeSH
- thiaziny farmakologie MeSH
- uracil analogy a deriváty farmakologie chemická syntéza MeSH
- valeráty farmakologie MeSH
- Check Tag
- lidé MeSH