Neuroprotective Effect Of H₂S On Neuronal Damage Induced By Ischemia/Reperfusion

Objective: In order to reveal whether Hydrogen Sulfide（H₂S） had a protective effect on the neuronal damage induced by ischemia/reperfusion, the changes in the behavioral ability, the expressions of nuclear factor kappa B（NF-κBp65）, cyclooxygenase-2（COX-2） and Caspase-3 were investigated in the hippocampus of rats with vascular dementia（VaD） due to ischemia and cellular model of ischemia-reperfusion injury by using SH-SY5 Y cells treated with OGD/R method Methods: The rat model with VaD was established by the modified method with four vessel occlusion. The experimental rats were divided randomly into groups with three periods by the drug（NaHS） treatments, i.e., 1, 7 and 30 days. In each period, the animals were divided into four sub-groups, i.e., Sham-operated, VaD, Low-dose（H₂S）and High-dose（H₂S） groups. In the Low-dose group the rats were intraperitoneally injected with 30 μmol NaHS /L per day, in the High-dose group with 100 μmol NaHS/L per day, and in the Sham-operated and the VaD groups with saline once a day. The learning and memory ability of the rats was measured by Morris Water Maze test. The SH-SY5 Y cells viabilities influenced by OGD/R were analyzed by CCK-8. The expressions of NF-κBp65, COX-2 and Caspase-3 were detected by Western blotting.All results obtained were analyzed by relating statistical methods. Results: 1. The escape latent period of the rats with 30 d in VaD group was significantly longer than that in the Sham-operated group. As compared with the VaD group, the escape latency was significantly decreased in rats of the Low- and High-dose groups. 2. In the control and OGD/R model groups, the SH-SY5 Y cell activity was significantly increased with the treatment of NaHS in a range of low concentration（0 <C <0.5mmol/L）. However, when the concentrations were more than the range, the cellactivity was obviously reduced. 3. The percentage of early apoptotic cells in model group were significantly higher than that in the control（P <0.05）. Compared with model group, the level of early apoptotic cells with 0.4mmol/LNaHS added was significantly reduced（P <0.05） while early apoptotic level of 4mmol/LNaHS group cells was significantly increased. 4. In each time period, the protein expressions of NF-κBp65, COX-2 and Caspase-3 in the brains of rats with VaD were significantly higher than those in the Sham group; while the expressions of NF-κBp65, COX-2 and Caspase-3 proteins in the Low-dose groups were significantly reduced than the VaD group. However, there were no significant differences in the expressions of NF-κBp65、COX-2 and Caspase-3 proteins between the High- and Low-dose groups.The level of NF-κBp65 expressed in the model group with OGD are higher than those in control group. the protein of NF-κBp65 expressed in the groups of dosing NaHS with the respectively concentrations of 0.2mmol/L, 0.4mmol/L and4mmol/L.Conclusion: VaD resulted from ischemia can increase the level of NF-κBp65, COX-2 and Caspase-3 in rat brains. NaHS at low concentration can decrease the expressions of NF-κBp65, COX-2 and Caspase-3, and therefore improve the ability of learning and memory of the rats, whichmay relieve the neuronal injury of rats with VaD. In addition, low concentrations of NaHS can decrease cellular hypoxic ischemic injury by promoting cell proliferation and reducing NF-κBp65expression and he level of early apoptotic in the cell model induced by ischemia-reperfusion, which may play a neuroprotective role.