Protective Effect Of Salidroside On Palmitic Acid-induced Cardiomyocyte Injury

Objective:To explore the effect and molecular mechanism of salidroside(SAL)against palmitic acid(PA)-induced injury for H9c2 cardiomyocytes.Methods:The lipotoxicity injury model of H9c2 cardiomyocytes was induced by PA in vitro.The cells were randomized into control group,PA group and SAL group.Cells in the model group were induced with 0.2 mmol·L^-1 PA for 24 h;Cells in SAL group were pretreated with20?mol·L^-1SAL for 1 h,and then treated with a final concentration of 0.2 mmol·L^-1PA and20?mol·L^-1SAL for 24 h.MTT(tetramethylazozoliun salt)assay was applied to evaluate the effect of PA and SAL treatment on H9c2 cardiomyocytes.Kits were used to detect superoxide dismutase(SOD)activity and malondialdehyde(MDA)content.Dihydroethidium(DHE)probe,Annexin V-FITC/PI staining,and JC-1 probe were used to detect intracellular reactive oxygen species(ROS)levels,cell apoptosis,and changes in mitochondrial membrane potential(MMP),respectively.The protein expression of AMPK/m TOR/p70S6K and apoptosis-related proteins Bax,Bcl-2,and cleaved caspase-3 were investigated with Western blotting.The m RNA levels of AMPK,m TOR and p70S6K were determined by quantitative reverse transcription-polymerase chain reaction(q RT-PCR).Results:(1)Compared with control group,PA reduced cell viability in a significant concentration-and time-dependent manner with the increase of PA concentration and treatment time.Similarly,cell viability decreased significantly after exposure to high fat conditions(0.2 mmol·L^-1 PA for 24 h)(P<0.01).PA decreased SOD activity and MMP levels,while increased MDA content,ROS levels(P<0.01)and cell apoptosis.PA decreased Bcl-2protein expression,while it increased Bax and cleaved caspase-3 protein expression.The expression of AMPK m RNA and protein were decreased in PA group(P<0.05 or P<0.01),but the expression of m TOR,p70S6K m RNA and protein were increased(P<0.05 or P<0.01).(2)Cell viaibity decreased by PA was significantly attenuated after pretreated with different concentration of SAL.The cell viability of H9c2 increased significantly when treated with a final concentration of 20 mmol·L^-1SAL compared to PA group(P<0.01).Pretreatment with SAL reversed the decreased SOD activity and MMP levels,then increased MDA content,ROS levels and cell apoptosis induced by PA(P<0.01).In addition,SAL reversed the elevation of Bcl-2 protein level,while it reduced the expression of Bax and cleaved caspase-3 in PA-induced cells(P<0.05).SAL promoted the expression of AMPK m RNA and protein,and suppressed the expression of m TOR,p70S6K m RNA and protein as compared to PA group(P<0.05 or P<0.01).Conclusion:SAL improved H9c2 cardiomyocyte injury induced by PA,relieved oxidative stress damage and mitochondrial injury,reduced cell apoptosis via mediating AMPK/mTOR/p70S6K signaling pathway.