The effects of exogenous hydrogen sulfide on injury of rat hippocampus neurons induced by oxygen-glucose deprivation and restoration

Objective To investigate the effects of exogenous hydrogen sulfide (H2S) on injury of rat hippocampus neurons induced by oxygen-glucose deprivation and restoration (OGD/R) and explore its mechanism.Methods Hippocampus neurons were isolated from embryonic day 16-18 (E16-18) rat embryos.Hippocampus was immediately removed and digested with 0.25％ trypsin.The neurons were isolated and cultured at 37 ℃ for 7 days and neuron-specific enolase (NSE) was detected by immunohistochemical staining method to identify neurons.At 8th day,the neurons were placed in deoxygenated glucose-free medium and exposed to 95％ N2-5％ CO2 in an air tight chamber for 1 hour,and then replaced the glucose-free medium with original medium,and returned the cultures to a standard incubator in 5％ CO2 at 37 ℃ and incubated for another 24 h.The neurons were divided into 3 groups:group Ⅰ control; group Ⅱ OGD/R,and group ⅢOGD + NaHS,the latter was further divided into 5 subgroups:groups Ⅲ1-5 with 25,50,100,200,400 μmol/L NaHS added,respectively.Then cell viability was quantified by MTT method,the level of lactate dehydrogenase (LDH) were detected,apoptosis was measured by Annexin V FITC/PI Apoptosis Kits,and RT-PCR was used to assay HIF-1 α mRNA in neurons in all groups.Results Compared with control group,the LDH level,apoptosis and expression of HIF-1α mRNA in group Ⅱ were significantly increased,the cell viability was significantly decreased (P ＜ 0.01).There were no significant differences in the LDH level,apoptosis and expression of HIF-1 α mRNA and the cell viability between group Ⅱ and group Ⅲ1 (P ＞ 0.05).Compared with group Ⅱ,the LDH level,apoptosis and expression of HIF-1α mRNA in group Ⅲ2-4 were significantly increased,the cell viability was significantly increased (P ＜ 0.01).Compared with group Ⅱ,the LDH level,apoptosis and expression of HIF-1 α mRNA in the group Ⅲ 5 were significantly decreased,the cell viability was significantly decreased (P ＜ 0.01).Conclusions H2S of low concentration has no significant effects on injury of rat hippocampus neurons induced by OGD/R.H2S of moderate doses can protect rat hippocampus neurons from OGD/R injury and H2S of high concentration can aggravate injury.The expression of HIF-1α mRNA in rat hippocampus neurons was increased after OGD/R,and the protective role of H2S is associated with increase in the expression of HIF-1α mRNA. Key words: Hydrogen sulfide;  Oxygen-glucose deprivation and recovery ;  Hippocampal neurons ; Apoptosis;  Hypoxia-induced factor-1α