HBO should be applied within 3–6 h when the ischemic neuronal tissues can still be saved16 (link). Due to possible toxicity of oxygen, the duration of HBO sessions should ranges from 60 to 90 minutes and the oxygen pressure should not exceed 3 ATA, whereby the most used pressure range from 1.5 to 3 ATA16 (link). In our study rats were exposed to HBO at 2 ATA for 60 min in a research hyperbaric chamber (1300B; Sechrist) at the onset of reperfusion. Compression and decompression were maintained at a rate of 5 psi/min. NAD+(Sigma-Aldrich), ATP synthase inhibitor Oligomycin A (Olig A, Santa Cruz Biotechnology), or NAMPT inhibitor FK866 (Tocris Bioscience) was administrated 30 min before HBO treatment. The vehicle group was given 5% dimethyl sulfoxide (DMSO, Sigma-Aldrich). Based on previous reports indicating that NAD+ administered intraperitoneally at a dosage from 50 mg/kg to 200 mg/kg have beneficial cytoprotective effects, we used 100 mg/kg, which turn out to be effective in our model17 (link), 18 (link). 10 mg/kg of FK866, NAMPT inhibitor, was administrated intraperitoneally as previously described19 (link); Sirt1 siRNAs was administrated intralateroventricularlly20 (link) and Olig A was administrated 1 mg/ml i.p21 (link).