【 Objective】 To investigate the effect of Sirtuin3 (SIRT3) on hypoxic preconditioning (Hyp) with its gene knocked down. 【Methods】 Empty vectors (pGCSIL-GFP) were used to select the suitable MOI. pGCSIL-PUR-SIRT3 -vectors were used in formal experiments. Cells transfected with empty vectors or SIRT3-RNAi-LV were divided into control

hypoxic preconditioning + Oxygen-glucose deprivation (Hyp+OGD) and Oxygen-glucose deprivation (OGD) respectively. MTT assay was used for testing the cells viability. The ATP level was evaluated using ATP Fluorometric Assay Kit. The expression of SIRT3

Peroxisome proliferator-activated receptor-γ coactivator-1α (PGC-1α) and Manganese superoxide dismutase (MnSOD) were assessed at the protein level by Western blot. 【Results】 After OGD

MTT values decreased more in SIRT3-/- compared with Vector (0.430±0.009 vs 0.562±0.140

P<0.01)

but were increased in Hyp+OGD respectively (P<0.05)

resulting in no significant difference between SIRT3-/- and Vector in Hyp+OGD (P=0.311>0.05). After OGD

The ATP levels decreased more in SIRT3-/- compared with Vector (0.334±0.006 vs 0.453±0.015

P<0.01)

but were increased in Hyp+OGD respectively (P<0.05)

resulting in no significant difference between SIRT3-/- and Vector in Hyp+OGD(P=0.866 >0.05). The expression of PGC-1α and MnSOD were declined significantly in the three groups of SIRT3-/- compared with that in Vector respectively (P < 0.05)

but were both increased in Hyp+OGD and OGD compared with control (P < 0.05)

and were increased more in Hyp+OGD compared with OGD (P< 0.05). 【Conclusion】The expression of PGC-1α and MnSOD were decreased with SIRT3 gene knocked down and SIRT3 was one of the ways that hypoxic preconditioning or hypoxia up regulated the expression of MnSOD through PGC-1α pathway.