Role Of Mitochondrial Permeability Transition Pore In Improving Spatial Learning And Memory Ability By Sevoflurane Postconditioning In A Rat Model Of Hemorrhagic Shock And

Objective To evaluate the role of mitochondrial permeability transition pore?mPTP?in improving spatial learning and memory ability by sevoflurane postconditioning in a rat model of hemorrhagic shock and resuscitation.Methods A total of 162 healthy adult male SD rats weighing 300-320 g were randomly divided into 9 groups?n=18?.They were the control group?Sham group?,the mPTP opener atractyloside group?Sham+Atr group?,the mPTP inhibitor cyclosporine A group?Sham+CsA group?,the hemorrhagic shock and resuscitation group?Shock group?,the sevoflurane postconditioning group?Shock+Sev group?,sevoflurane postconditioning+atractylosidegroup?Shock+Sev+Atrgroup?,sevoflurane postconditioning+cyclosporine A group?Shock+Sev+CsA group?,the hemorrhagic shock and resuscitation+atractyloside?Shock+Atr group?,the hemorrhagic shock and resuscitation+cyclosporin A group?Shock+CsA group?.The hemorrhagic shock and resuscitation model was established by extracting 40%of the total blood volume of the rat through the right common carotid artery within 30 min.After 1 h,all autologous blood was returned through the left external jugular vein at a constant rate within 30min.Shock+Sev group,Shock+Sev+Atr group and Shock+Sev+CsA group inhaled2.4%sevoflurane for 30 min while returning autologous blood.Sham+Atr group,Shock+Sev+Atr group and Shock+Atr group were intravenously injected with 5 ml/Kg Atr 10 min before the autologous blood was returned.Sham+CsA group,Shock+Sev+CsA group and Shock+CsA group received intravenous injection of 10mg/Kg CsA 30 min before hemorrhagic shock.During the experiment,the mean arterial pressure?MAP?of the rats was measured every 10 min through a manometer connected to the common carotid artery.The arterial blood gas were measured at the beginning of bleeding?baseline,T₀?,30 min after bleeding?30 min after the catheterization in Sham,T₁?,60 min after bleeding?90 min after the catheterization in Sham,T₂?,30 min after the reperfusion?120 min after the catheterization in Sham,T₃?,and PH,buffuer excess?BE?and the lactic acid?Lac?were recorded at each time point.Brains were harvested 24 h after operation to detect the expression of Bcl-2,Bax and cytochrome C by western blot,the opening of mitochondrial permeability transition pore by mitochondrial membrane channel pore assay kit,and the mitochondrial membrane potential by mitochondrial membrane potential assay kit.The Morris water maze test was used to detect the spatial learning and memory ability of rats after 72 h of resuscitation.The morphology of the cells was observed by hematoxylin-eosin staining,and the expression level of caspase-3 in hippocampus was detected by immunohistochemistry.Results Compared with the Sham group,the latency were prolonger?P<0.05?,the number of platform crossings,the swimming path and the proportion of time spent in the platform quadrant were significantly shorter?P<0.05?,the expression of Bcl-2 were lower and the expression of Bax,Cyt C and caspase-3 were higher?P<0.05?,the opening of mPTP were higher and the MMP were lower in the shock group?P<0.05?.Compared with the Shock group,sevoflurane postconditioning?Shock+Sev group?significantly decreased the latency,increased the the number of platform crossings,the swimming path and the proportion of time spent in the platform quadrant,up-regulated the expression of Bcl-2?P<0.05?,down-regulated the expression of Bax,Cyt C and caspase-3?P<0.05?,decreased the opening of mPTP and increased the MMP?P<0.05?.Compared with the Shock+Sev group,the Shock+Sev+Atr group had a longer latency,the number of platform crossings,the swimming path and the proportion of time spent in the platform quadrant were decreased,and the Bcl-2 expression in the hippocampus was down-regulated,the Bax,Cyt C and caspase-3 were up-regulated,the degree of mPTP opening was increased,and MMP was decreased?P<0.05?.It should be noted that these indexes in Shock+Sev group and Shock+CsA group were similar to each other.Conclusion Sevoflurane postconditioning improves the spatial learning and memory impairments induced by hemorrhagic shock and resuscitation through inhibiting the opening of mPTP.