Objective To investigate the role of HO-1 in inhibition of oxygen-glucose deprivation (OGD)-induced apoptosis in rat hippocampal neurons by sevoflurane preconditioning.Methods Hippoeanlpal neurons of newborn Wistar rats (<48 h) were cultured in vitro.Tne neurons were randomly divided into 6 groups with 108 wells in each group:control group(group C),2% sevoflurane preconditioning group (group S1),OGD group,S1 +OGD group,4% sevoflurane preconditioning+OGD group (group S2+OGD),and 4% sevoflurane preconditioning+ZnPPⅨ+OGD group(group Z).Group C received no treatment.The neurons were cultured for 24 h after 2% sevoflurane preconditioning in group S1.For OGD experiments,the neurons were placed in deoxygenated glucose-free medium and sealed under 95% N2-5% CO2 in an anaerobic chamber equilibrated to 37℃ and 100%humidity for 45 min.then OGD was terminated by replacement of the stored medium and returning the cultures to a standard incubator maintained at 37℃ in 5% C02 and the neurons were cultured for 24 h as described by Ray et al. The OGD model was established after 2% and 4% sevoflurane preconditioning in group S1 + OGD and S2 + OGD respectively. In group Z, when the neurons were preconditioned with 4% sevoflurane, ZnPPⅨ was added to the culture medium at the same time, and the other procedures were the same as those in group S2 + OGD. The neuron viability, apoptesis rate, and expression of HO-I protein and mRNA were detected at 24 h of culture. Results Compared with group C, neuron viability was significantly decreased,apoptosis rate was significantly increased, and expression of HO-1 protein and mRNA was up-regulated in group OGD, S1 + OGD, S2 + OGD and Z, expression of HO-1 protein and mRNA was up-regulated in group S1 ( P < 0.01 ), but no significant change was found in neuron viability and apoptosis rate in group S1 ( P > 0.05). Compared with group OGD, neuron viability was significantly increased, apoptosis rate was significantly decreased, and expression of HO-1 protein and mRNA was up-regulated in group S1 + OGD and S2 + OGD ( P < 0.01), but no significant change was found in the indexes mentioned above in group Z ( P > 0.05 ). Neuron viability was significantly higher, apoptosis rate lower and expression of HO-1 protein and mRNA higher in group S2 + OGD than in group S1 + OGD ( P < 0.01). Neuron viability was significantly lower, apoptosis rate higher and expression of HO-1 protein and mRNA lower in group Z than in group S2+OGD(P<0.01).Conclusion HO-1 is involved in the inhibition of OGD-indueed apoptosis in rat hippocampal neurons by sevoflurane preconditioning.