beta-Hydroxy-beta-methylbutyrate (HM beta) supplementation stimulates skeletal muscle hypertrophy in rats via the mTOR pathway

beta-Hydroxy-beta-methylbutyrate (HM beta) supplementation is used to treat cancer, sepsis and exercise-induced muscle damage. However, its effects on animal and human health and the consequences of this treatment in other tissues (e. g., fat and liver) have not been examined. the purpose of this study was to evaluate the effects of HM beta supplementation on skeletal muscle hypertrophy and the expression of proteins involved in insulin signalling. Rats were treated with HM beta (320 mg/kg body weight) or saline for one month. the skeletal muscle hypertrophy and insulin signalling were evaluated by western blotting, and hormonal concentrations were evaluated using ELISAs. HM beta supplementation induced muscle hypertrophy in the extensor digitorum longus (EDL) and soleus muscles and increased serum insulin levels, the expression of the mammalian target of rapamycin (mTOR) and phosphorylation of p70S6K in the EDL muscle. Expression of the insulin receptor was increased only in liver. Thus, our results suggest that HM beta supplementation can be used to increase muscle mass without adverse health effects.Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)Fed Univ São Paulo UNIFESP, Dept Physiol Nutr, São Paulo, BrazilState Univ Campinas UNICAMP, Dept Internal Med, FCM, Campinas, SP, BrazilUniv São Paulo, Dept Cell Biol & Dev, Mol Cell Biol Study Grp, Inst Biomed Sci 1, São Paulo, BrazilState Univ Campinas UNICAMP, Fac Appl Sci, Limeira, SP, BrazilFed Univ São Paulo UNIFESP, Dept Biosci, São Paulo, BrazilFed Univ São Paulo UNIFESP, Dept Physiol Nutr, São Paulo, BrazilFed Univ São Paulo UNIFESP, Dept Biosci, São Paulo, BrazilFAPESP: 2008/03533-1Web of Scienc