Abstract: BACKGROUND: Studies have shown that Lycium barbarum polysaccharide can delay muscle fiber atrophy in mouse skeletal muscle, but there are few studies on its effects on skeletal muscle mitochondrial function and antioxidant enzymes in rats after heavy exercise.
OBJECTIVE: To investigate the effects of Lycium barbarum polysaccharide on skeletal muscle mitochondrial function and antioxidant enzymes in mice after heavy exercise.
METHODS: Sixty Sprague-Dawley rats were randomly divided into five groups: a blank group, a model group, a low-dose Lycium barbarum polysaccharide group, a medium-dose Lycium barbarum polysaccharide group, and a high-dose Lycium barbarum polysaccharide group. Except the blank group, the rats in the other four groups underwent heavy exercise training. The blank and model groups were given the same amount of normal saline every day, and the low-, medium- and high-dose Lycium barbarum polysaccharide groups were given 25, 50, 100 mg/kg Lycium barbarum polysaccharide every day, 30 minutes before exercise, for 2 weeks. Blood lactate, hepatic glycogen, myo-glycogen, testosterone levels and mitochondrial respiratory chain complex I-IV activities in the skeletal muscle of rats in each group were detected according to the kit instructions. The activities of superoxide dismutase, catalase and glutathione peroxidase in serum and skeletal muscle were determined by enzyme-linked immunosorbent assay. Western blot analysis was used to detect the protein expression levels of phosphorylated AMP-activated protein kinase α, peroxisome proliferator-activated receptor-γ coactivator 1α, nuclear factor erythroid 2-related factor 1, and nuclear factor erythroid 2-related factor 2.
RESULTS AND CONCLUSION: (1) Compared with the blank group, liver glycogen, muscle glycogen and testosterone levels in the model group were significantly decreased, and blood lactic acid level was significantly increased (P < 0.05); compared with the model group, liver glycogen, muscle glycogen and testosterone levels were significantly increased and blood lactic acid level was significantly decreased in the low-, medium- and high-dose Lycium barbarum polysaccharide groups in a dose-dependent manner (P < 0.05). (2) Compared with the blank group, mitochondrial respiratory chain complex I-IV activities in the model group were significantly decreased (P < 0.05); compared with the model group, the activities of mitochondrial respiratory chain complexes I-IV in the low, medium-, and high-dose Lycium barbarum polysaccharide groups were significantly increased in a dose-dependent manner (P < 0.05). (3) Compared with the blank group, the activities of superoxide dismutase, catalase and glutathione peroxidase in bone tissue and serum of the model group were significantly decreased (P < 0.05); compared with the model group, the activities of superoxide dismutase, catalase and glutathione peroxidase in bone tissue and serum of low-, medium- and high-dose Lycium barbarum polysaccharide groups were significantly increased in a dose-dependent manner (P < 0.05). (4) Compared with blank group, the protein expression levels of phosphorylated AMP-activated protein kinase α, peroxisome proliferator receptor-γ coactivator 1α, nuclear factor E2 associated factor 1 and nuclear factor E2 associated factor 2 in the model group were significantly decreased (P < 0.05); compared with the model group, the protein expression levels of phosphorylated AMP-activated protein kinase α, peroxisome proliferator receptor-γ coactivator 1α, nuclear factor E2 associated factor 1 and nuclear factor E2 associated factor 2 in the low, medium- and high-dose Lycium barbarum polysaccharide groups were significantly increased in a dose-dependent manner (P < 0.05). To conclude, Lycium barbarum polysaccharide could improve skeletal muscle mitochondrial function and increase antioxidant enzyme activity in serum and skeletal muscle tissue of rats after heavy exercise, which may be associated with the elevated expression of phosphorylated AMP-activated protein kinase α, peroxisome proliferator receptor-γ coactivator 1α, nuclear factor E2 associated factor 1 and nuclear factor E2 associated factor 2.

中国组织工程研究杂志出版内容重点：组织构建；骨细胞；软骨细胞；细胞培养；成纤维细胞；血管内皮细胞；骨质疏松；组织工程

Key words: Lycium barbarum polysaccharide, heavy load exercise, skeletal muscle, mitochondrial function, antioxidant oxidase, engineered tissue construction