The preventive effect of β-carotene on denervation-induced soleus muscle atrophy in mice

Muscle atrophy increases the production of reactive oxygen species and the expression of atrophy-related genes, which are involved in the ubiquitin-proteasome system. In the present study, we investigated the effects of beta-carotene on oxidative stress (100 mu M-H2O2)-induced muscle atrophy in murine C2C12 myotubes. beta-Carotene (10 mu M) restored the H2O2-induced decreased levels of myosin heavy chain and tropomyosin (P<0.05, n 3) and decreased the H2O2-induced increased levels of ubiquitin conjugates. beta-Carotene reduced the H2O2-induced increased expression levels of E3 ubiquitin ligases (Atrogin-1 and MuRF1) and deubiquitinating enzymes (USP14 and USP19) (P<0.05, n 3) and attenuated the H2O2-induced nuclear localisation of FOXO3a. Furthermore, we determined the effects of beta-carotene on denervation-induced muscle atrophy. Male ddY mice (8 weeks old, n 30) were divided into two groups and orally pre-administered micelle with or without beta-carotene (0.5 mg once daily) for 2 weeks, followed by denervation in the right hindlimb. beta-Carotene was further administered once daily until the end of the experiment. At day 3 after denervation, the ratio of soleus muscle mass in the denervated leg to that in the sham leg was significantly higher in beta-carotene-administered mice than in control vehicle-administered ones (P<0.05, n 5). In the denervated soleus muscle, beta-carotene administration significantly decreased the expression levels of Atrogin-1, MuRF1, USP14 and USP19 (P<0.05, n 5) and the levels of ubiquitin conjugates. These results indicate that beta-carotene attenuates soleus muscle loss, perhaps by repressing the expressions of Atrogin-1, MuRF1, USP14 and USP19, at the early stage of soleus muscle atrophy.