Abstract： Objective To investigate the role and mechanism of SIRT1 in regulating the apoptosis of chondrocytes in vitro. Methods The articular chondrocytes from New Zealand rabbits were routinely cultured and divided into 3 even groups( n =10):SIRT1 activator (resveratrol) group,control group and SIRT1 inhibitor (nicotinamide) group.The apoptosis of chondrocytes was induced by sodium nitroprusside (SNP).MTT assay was used to detect the activity of cartilage cells in each group.DAPI staining and flow cytometry were applied to detect the apoptosis of chondrocytes.Western Blot was used to detect the expressions of SIRT1,p53,NF-κB,bax,PGC-1α in the cells in each group.RT-PCR method was applied to detect the mRNA expressions of SIRT1,type Ⅱ collagen and aggrecan in the cells in each group. Results The average OD value was 0.139 ±0.016 in the SIRT1 activator group,0.098 ±0.006 in the control group and 0.079 ± 0.002 in the SIRT1 inhibitor group.There was a significant difference among the 3 groups ( F =51.273,P =0.000) and between groups as well ( P ＜ 0.05).In terms of cellular apoptosis,the SIRT1 inhibitor group is the highest,the control group lower and the SIRT1 activator group the lowest.Compared with the control group,the expressions of SIRT1 and PGC-1α were increased in the SIRT1 activator group but decreased in the SIRT1 inhibitor group.The expressions of p53,NF-κB and bax were lower in the SIRT1 activator group than in the control group while those were higher in the SIRT1 inhibitor group.The mRNA expressions of SIRT1,type Ⅱ collagen and aggrecan were the highest in the SIRT1 activator group,lower in the control group and the lowest in the SIRT1 inhibitor group. Conclusion SIRT1 may regulate the apoptosis of chondrocytes by regulating the expressions of p53 and NF-κB which in turn changes the expressions of downstream bax and PGC-1α.