Melatonin Treats Osteoporosis Via SIRT1-Mediated Antioxidant Mechanisms

Objective:to research the role of melatonin(MT)in the treatment of osteoporosis(OP).With the help of orthopaedics surgery,stem cell technology and oxidative free radical medicine,we would like to explain the antioxidant mechanisms thoroughly and provide new ways to cure osteoporosis.Methods:8-week old female Sprague-Dawley rats were ovariectomized(OVX)to induce osteoporosis.3 months after OVX and Sham operation,bone marrow mesenchymal stem cells(BMMSCs)were derived and cultured.Afterwards,examine the changes of OP-BMMSCs in proliferation,osteogenesis and antioxidation.In vitro,we treat OP-BMMSCs with 1?M and 100?M MT.Proliferation of cells was measured by CCK-8.Osteogenic differentiation was measured by Alizarin Red S staining and osteogenic genes(RUNX2,SP7,BGLAP)were detected by RT-PCR.Measuring intracellular(reactive oxygen species)ROS,superoxide,hydrogen peroxide(H2O2)and activity of total superoxide dismutase(SOD),SOD2,peroxidase by various kits.Antioxidant genes and proteins(SOD1,SOD2,CAT,GPX1,SIRT1)were also detected to evaluate antioxidant properties.Afterwards,SIRT1 inhibitors were involved in the experiments explore the importance of SIRT1.In vivo,MT was administrated via tail vein,the microstructure of bone issue was observed by Micro-CT and H-E staining.BMMSCs of rats in vivo experiments were also isolated and detected to research the role of MT and SIRT1.Results:Decline of proliferation,osteogenesis and antioxidant properties was found in BMMSCs isolated from OVX rats.Treatment of MT restored proliferation and osteogenesis of OP-BMMSCs.Osteogenic genes(RUNX2,SP7,BGLAP)were up-regulated obviously by MT.In the vitro experiment,MT attenuated intracellular ROS,superoxide,H2O2 and increased activity of total SOD,SOD2 and peroxidase.The levels of antioxidant genes and proteins were also enhanced by MT.When using SIRT1 inhibitors,MT's effect on osteogenic and antioxidant properties were weakened.It proved that SIRT1 played an important role in the process.In vivo,improved BMD and BV/TV were found in MT-injected rats'femurs.Micro-CT data and H-E staining both proved that intravenous injection of MT preserves bone microstructure of OVX rats.After isolating BMMSCs from rats,we found osteogenic and antioxidant properties were also improved.Besides,when we injected SIRT1 inhibitor and MT together into rats,the effect of MT declined obviously.It clarified SIRT1-mediated antioxidant mechanisms also played an important role in vivo treatment.Conclusion:MT improved antioxidant properties of OP-BMMSCs to restore its osteoporosis-impaired osteogenic potential via SIRT1-mediated antioxidant mechanisms.It also preserved bone loss of rats caused by osteoporosis.