Effect Of Hydrogen-rich Saline On Hippccampus Endoplasmic Reticulum Stress After Cardiopulmonary Resuscitation In Rats

Objective:As a new type of antioxidant,hydrogen-rich saline can selectively scavenge reactive oxygen species(ROS)and protect cerebral against ischemia reperfusion(I/R)injury.Endoplasmic reticulum stress(ERS)has been implicated in the pathological process of cerebral ischemia.In addition to the Death receptors pathway and mitochondrial pathway,ERS has been considered to be a new kind of apoptosis mechanism However,very little is known about the role of hydrogen-rich saline in mediating pathophysiological reactions to ERS after I/R injury caused by cardiac arrest and resuscitation.Therefore,we investigate whether hydrogen-rich saline can attenuate cerebral injury through suppressing ERS.Methods:The experiment will be divided into two parts.In Part Ⅰwe explored the effects of hydrogen-rich saline on survival rate and neurological function after cardiac arrest and resuscitation in rats.65 SD rats were included in the experiment and 15 rats were excluded.Finally 50 rats were distributed into three groups:sham(group S,n=10),ischemia reperfusion(group I/R,n=20)and hydrogen-rich saline(group H,n=20).The rats in group S and group H were subjected to 4 minutes of cardiac arrest induced by transoesophageal cardiac pacing.Then they were randomized to receive 5ml/kg of either hydrogen-rich saline or normal saline at the beginning and 6 h of return of spontaneous circulation(ROSC).The survival rate in 7 days after ROSC were recorded and the neurological deficit scores were evaluated at 24 h,72h and 7 days after ROSC.In Part Ⅱ,we explored the effects of hydrogen-rich saline on ERS after cardiac arrest in rats.Additional 63 rats were used in experiment 2,and finally 45 rats were included.The morphological changes and apoptosis of pyramid cells in hippocampal CA1 region were examined by hematoxylin and eosin staining(HE)and terminal deoxynucleotidyl transferase-mediated dUTP nick end labeling(TUNEL)at 24 h after ROSC.The expressions of ERS marker proteins,such as glucose-regulated protein 78(GRP78),cysteinyl aspartate specific proteinase-12(caspase-12)and C/EBP homologous protein(CHOP)were detected by Western Blot at 6 h,12 h and 24 h after ROSC.Apoptosis proteins caspase-3,Bcl-2 assaciated x protein(Bax)and antiapoptotic proteins B-cell lymphoma-2(Bcl-2)were also examined by Western Blot.The expressions of ROS in hippocampus were detected by spectrophotometer at 24 h after ROSC.Results:Compared with group I/R,hydrogen-rich saline could significantly improve the survival rate at 7 days after ROSC(p<0.05),and neurological function at 24 h,72 h and 7 days after ROSC.Compared with group I/R,hydrogen-rich saline could significantly increase the number of survival neurons in hippocampus CA1 region(p<0.05).Besides,hydrogen-rich saline markedly up-regulated the expression Bc1-2,down-regulated Bax and caspase-3 at 24 h after ROSC(p<0.05).Furthermore,the protective effects of hydrogen-rich saline were accompanied by the increased activity of GRP78,the decreased activity of caspase-12 and CHOP(p<0.05).Meanwhile,the production of ROS in group H was less than group I/R 24 h after ROSC(p<0.05).Conclusions:Hydrogen-rich saline treatment may attenuate cerebral I/R injury through inhibiting hippocampus ROS-dependent ERS after cardiopulmonary resuscitation in rats.