Dynamic Change Regularity Of Spermidine/Spermine-N1-Acetyltransferase 2(SSAT2) And Hypoxia Inducible-1A In The Cerebral Cortex Of Rat After Cardiopulmonary Resuscitation

Part 1 Establishment of a rat model with cardiopulmonary resuscitationObjective: To establish a stable model of rat with cardiopulmonary resuscitationMethods: 66 adult SD rats were randomly divided into control groups (n=8), sham surgery groups (n=8) and cardiopulmonary resuscitation (CPR) groups (n=50).The model of rats with cardiopulmonary resuscitation was made by injection of the ice-cold potassium chloride solutions into right atrium through external jugular vein, and the resuscitation efforts were started immediately at the point of 5 minutes since the cardiac arrest happened, the method of oral trachea cannula instead of tracheotomy was carried out in sham surgery groups. Basic vital signs were monitored and the time of inducing cardiac arrest and return of spontaneous circulation (ROSC) were recorded. Neural deficit scores (NDS) were evaluated at the points of 24h, 72h after ROSC and the morphologic changes of cerebral cortexes were observed with optical microscope at the points of 1h, 24h, and 72h after ROSC.Results: The cardiac arrest was induced rapidly by the injection of KCl in CPR groups. The time of ROSC were (343.6±120.2) s, while ROSC rate was 80%(40/50). The survive rate were 76% at 24h, and 74% at 72h after ROSC respectively. NDS were (64.73±1.66) at 24h and (73.19±1.33) at 72h after ROSC respectively. The cerebral cortexes presented very severe ischemic and anoxic damage at 1h, and then moderately severe damage at 24h, and mild severe damage at 72h after ROSC.Conclusions: The model of rat with cardiopulmonary resuscitation has the advantage of simple establishment and easy resuscitation, ant it is stable and reliable. The improved model with using trachea cannula instead of tracheotomy minimizes tissue damage and reduces the impact on the body. So we think this model is more suitable for researching cerebral resuscitation after CPR. Part 2 Dynamic change regularity of spermidine/spermine-N1-acetyltransferase 2(SSAT2) and hypoxia inducible -1αin the cerebral cortex of rat after cardiopulmonary resuscitationObjective: To study the relationship of spermidine/spermine-N1- acetyltransferase 2 (SSAT2) and hypoxia inducible -1α(HIF-1α) in the cerebral cortex of rat after cardiopulmonary resuscitation (CPR).Methods: 88 adult SD rats were randomly assigned to the following three groups: Control (n=8), Sham surgery (n=40), CPR (n=40). Sham surgery and CPR groups were further divided into 1, 8, 24, 48 and 72 h subgroups (n=8). Cardiac arrest (CA) was induced by the rapid sequential intra-atrial injection of ice-cold potassium chloride solution and resuscitation efforts began after 5 min of arrest. HIF-1α, SSAT2 and HIF-1αmRNA in the cerebral cortex were measured by western blot and RT-PCR respectively.Results: SSAT2 protein level reduced markedly at 1h point (0.314±0.027, P<0.01), and then the descendent tendency weaken gradually (P<0.01), and the level of SSAT2 protein restored to normal level (0.736±0.02) at 72 h point (0.731±0.024, P>0.05) in CPR groups. The expressions of SSAT2 in control and sham surgery groups were not significantly different (P>0.05). HIF-1αmRNA level fell distinctly at 1 h point (0.245±0.021, P<0.05) and reached the peak at 8h point (0.430±0.019, P<0.05), and then increased weakly at 24 h point (0.387±0.018, P<0.05) and 48 h point (0.385±0.019, P<0.05), and recovered to normal level (0.343±0.022) at 72h point in CPR groups. The expressions of HIF-1αprotein were strongly positive at 1 hr point (0.755±0.012, P<0.01), and then the increased tendency attenuated gradually (P<0.01), and the expressions of HIF-1αprotein were weakly positive at 72h (0.033±0.002, P<0.01) point in CPR groups. HIF-1αwas undetectable in control and sham surgery groups. The level of SSAT2 protein was negatively correlated with the HIF-1αprotein expression level within 72h (r=-0.945,P<0.001), and with the HIF-1αmRNA expression level between 8 h and 48 h (r=-0.614, P=0.001) in CPR groups.Conclusion: The expressions of HIF-1αprotein and mRNA and SSAT2 changed with the resuscitation time varied in the cerebral cortex of rat after CPR. SSAT2 expressions decreased during 72h, while HIF-1αprotein increased within 72h and HIF-1αmRNA also was up-regulation between 8 h and 48 h, which may indicate that SSAT2 may negatively regulate the expression of HIF-1αprotein and mRNA in the cerebral cortex of rat after CPR.