Experimental Study On Mechanism Of Neuronal Cell Damage After Cardiopulmonary Resuscitation In Rats

Objective: To investigate the mechanism of neuronal cell damage after global ischemia-reperfusion.Methods: Cardiac arrest was induced by asphyxiation and ice-cold 0.5M Kcl.in rats and resuscitation efforts were begun five minutes after arrest.28 Sprague Dawley rats, half female and half male, were randomly divided into 5 groups: sham control group (n=4); after cardiopulmonary resuscitation rats were allowed to reperfuse spontaneously for 3 hours,6hours,12hours and 24hours(n=6,per group).Brain-specific isozyme of creatine phosphokinase(CK-BB), levels of tumor necrosis factor α( TNF-α) and interleukin-1β(IL-1β) in blood were measured after cardiopulmonary resuscitation,The neurological status was evaluated in 6hours,12hours and 24hours groups. The temporospatial cellular reactions were assessed by terminal deoxynucleotidyltransferase-mediated dutp-FITC nick endlabeling(TUNEL) and transmission electron microscope(TEM). bcl-2,bax,bak and NF-κB protein expression were studied using immunocytochemistry at 3 hour,6hour,12hour and 24hour after resuscitation.Result: CK-BB levels in 3 hour group began to rise and were markedly higher at 6 hour compared to other groups. We cannot find any elevations about the levels of TNF-αand IL-1βduring the study period. Brain of sham-operated rats contained no apoptosis . TEM revealed and early onset apoptosis in cortex at 3 hour after resuscitation. At 12 hour post-resuscitation, TUNEL-positive cells could be observed in the hippocampal. there were 6.0% TUNEL-positive cells at 24 hour. Bcl-2 immunoreactivity was continuous to increase, but bax protein expression was higher than Bcl-2, bcl-2/bax ratio imbalance. Nuclear NF-κB protein expression was early observed at 6 hour, there were 11.2% NF-κB-positive cells in the hippocampal at 24 hour.Conclusion: Apoptosis is one mechanism of neuronal cell gamage after global ischemia-reperfusion,the results of this study demonstrate that bcl-2/bax ratio imbalance and NF-κB expression have an important role in progammed cell death...