Effects of different doses of PcTx1 on global cerebral ischemia-reperfusion injury in rats

Abstract

Objective To explore the effects of different doses of PcTx1,a specific blocker of acid-sensing ion channel 1a,on global cerebral ischemia/repedfusion (I/R) injury in rats,Methods Sixty adult male Sprague Dawley rats (weighing 250-300 g) were randomly divided into 6 grups ( n =10 each):sham operation group (group S),I/R group,different doses of PcTx1 ( 10 ng/ml,group P1 ; 25 ng/ml,group P2 ; 50 ng/ml,group P3 ;and 500 ng/ml,group P4 ) groups.Global cerebral ischemia was induced by the modified procedure of Pulsinelli 4-vessel occlusion.In groups P1,P2,P3 and P4,different doses of PcTx1 ( 10,25,50 and 500 ng/ml),6 μl each,were respectively injected into the lateral cerebral ventricle at the initiation of reperfusion,while equal volume of double distilled water was injected instead in group I/R.Six rats in each group were sacrificed at 24 h of reperfusion,and the brains were immediately removed,Thereafter,the contents of malondialdehyde (MDA),reduced glutathione (GSH) and ritric oxide (NO),the activities of constitutive NO synthase (eNOS) snd inducible NO synthase (iNOS) were detected in hippocampus.Four rats in each group were sacrificed at 72 h of reperfusion,and hematoxylin and eosin staining was used to observe the pathomorphological changes of the hippocampal neurons.Results Compared with group S,the other groups showed decreases in the contents of GSH,while increases in the contents of MDA and NO and the activities of cNOS and iNOS ( P ＜ 0.05 or 0.01 ).The contents of GSH increased,while the contents of MDA and NO and the activities of cNOS and iNOS decreased in groups P2,P3 and P4 compared with group I/R ( P ＜ 0.05 or 0.01).Compared with group P1,the contents of GSH increased,the contents of MDA and the activities of cNOS decreased in groups P2,P3 and P4,and the contents of NO and the activities of iNOS decreased in groups P3 and P4 ( P ＜ 0.05 or 0.01 ).Compared with group P2,the activities of iNOS decreased in groups P3 and P4(P ＜ 0.05 or 0.01).The damage to neurons in hippocampal CAI was severe in groups I/R and P1,but it was attenuated in groups P3 and P4.Conclusion PcTx1 25,50 and 500 ng/ml (6 μl)injected into lateral cerebral ventricle can attenuate global cerebral I/R injury in rats,and the dose 50 ng/ml (6 μl) is more suitable. Key words: Ion channels; Protons; Brain; Reperfusion injury