Polygonatum cyrtonema Hua polysaccharide exhibits anti-fatigue activity via regulating osteocalcin signaling

In the present study, we explored the anti-fatigue activity and its potential mechanism of a purified Polygonatum cyrtonema polysaccharide (PCP) on mice using weight-loaded swimming test. Results showed that PCP remarkably prolonged the exhaustive swimming time of mice when compared with normal control group. Meanwhile, PCP decreased serum levels of lactic acid (LA), blood uric nitrogen (BUN), superoxide dismutase (SOD), glutathione peroxidase (GSH-Px) and malondialdehyde (MDA), and increased the contents of liver glycogen, muscle glycogen and muscle ATP. These results revealed that PCP had good anti-fatigue ability. The histomorphologic analysis showed that PCP increased the cross-section area of the muscle fibers. Furthermore, PCP significantly enhanced the protein levels of bone morphogenetic protein-2 (BMP-2), phosphor-Smad1, Runt-related transcription factor 2 (Runx2) and osteocalcin (OC) in skeleton. Similar variation was also observed in the expression of osteocalcin signaling mediators of phosphorylated cAMP-response element binding protein (p-CREB) and phosphorylated hormone-sensitive lipase (p-HSL) in skeletal muscle. These results suggested that PCP resisted fatigue possibly via regulating osteocalcin signaling.