Effects of beta-hydroxy-beta-methylbutyrate supplementation on skeletal muscle in healthy and cirrhotic rats
Abstract
Beta-hydroxy-beta-methalburyrate (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 CCl14-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 CCl14-treated rats are detrimental. Furhter studies examining the effecrts 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.