Abstract: The alleviating effect and mechanism of Ganoderma lucidum polysaccharides (GLPs) on exercise-induced fatigue were investigated using network pharmacology approaches based on their bioactive characteristics. Male Kunming (KM) mice were randomly assigned to a resting control group, an exercise-induced fatigue group, and three GLP intervention groups at low, medium, and high doses. All groups except the control group underwent exercise for 8 continuous weeks, follow by the collection of blood and gastrocnemius muscle samples for the assessment of fatigue indicators, glucose and lipid metabolism parameters, and muscle histopathology. The potential targets of GLPs and muscle injury target genes were predicted using the TargetNet and SwissTargetPrediction databases. Protein-protein interaction (PPI) networks were constructed and topologically analyzed using String and Cytoscape 3.7.2 software. Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway enrichment analyses were conducted to identify the underlying mechanistic pathways. Western blot was employed to measure the expression of proteins related to the glucose and lipid metabolism pathways in the gastrocnemius muscle. The results demonstrated that GLPs significantly reduced serum lactate, urea nitrogen, and lactate dehydrogenase levels in fatigued mice, while increasing muscle glycogen, liver glycogen, and free fatty acid concentrations. Additionally, GLPs enhanced succinate dehydrogenase and Ca2+-Mg2+-ATPase activities and improved muscle cell morphology. Network pharmacology analysis revealed that GLPs were composed of eight monosaccharides, including L-fucose, D-mannose, and L-arabinose. Hsp90aa1, Hsp90ab1, Mmp9, and Src were identified as key protective targets of GLPs against muscle injury, and the glycolysis/gluconeogenesis and metabolic pathways as potential signaling pathways. Compared with the exercise fatigue group, GLPs-treated mice showed greatly increased expression of AMP-activated protein kinase (AMPK), phosphorylated AMPK, and peroxisome proliferator-activated receptor gamma coactivator 1-alpha (PGC-1α), and the transmembrane transporter protein cluster determinant 36 (CD36) in the gastrocnemius muscle. These results suggest that GLPs could alleviate exercise-induced fatigue and ameliorate glucose and lipid metabolism disorders in fatigued mice by regulating the AMPK/PGC-1α signaling pathway.

Key words: Ganoderma lucidum polysaccharides; exercise-induced fatigue; glycolipid metabolism; AMP-activated protein kinase/peroxisome proliferators activate receptor γ cofactor 1-α signaling pathway; network pharmacology