The Relationship Between the Expression of Serum S100A8/A9 and the Degree of Brain Injury in Rats After Cardiopulmonary Resuscitation

Abstract

This study is to investigate the expression of serum S100A8/A9 in rats after cardiopulmonary resuscitation (CPR) and its correlation with brain injury after CPR. Thirty-six male SD rats were randomly divided into control group (n = 6), cardiopulmonary resuscitation group (n = 24) and sham operation group (n = 6). The cardiopulmonary resuscitation group was further divided into four subgroups according to the time after recovery of autonomous circulation: 6-hour group, 12-hour group, 24-hour group and 48-hour group, with 6 rats in each group. The rats in the cardiopulmonary resuscitation group was conducted by asphyxia then given cardiopulmonary resuscitation (CPR), while the rats in the sham operation group were given tracheal intubation without asphyxia. The rats in each group were assessed by modified Neurological Severity Score (mNSS). The vein blood from tail was collected to detect the expression of serum S100A8/A9. Then the brain tissue was taken to measure the water content. Our results showed that the neurological function of the sham-operated group and the control group was normal, the mNSS scores of which were 0. However, the neurological function score in the CPR group decreased gradually with time, but it was still significantly higher than that in the normal value until 48 hours (P < 0.05). There was no significant difference in brain water content between the sham-operated group and the control group (P > 0.05). The water content of brain tissue in sham-operated group was higher than that in control group at 6 h, and the amount was increasing as the time extended. The level reached the highest at 24 h and started to decrease at 48 h, but the it was still higher than that in sham-operated group (P < 0.05). The expression level of serum S100 A8/A9 in sham-operated group was slightly higher than that in control group, but there was no statistical difference (P > 0.05); The expression level of S100 A8/A9 in cardiopulmonary resuscitation group was significantly higher than that in control group at 6 h, and still increased at 24 h. Although the level decreased at 48 h, but was still higher than that in sham operation group (P < 0.05). The mNSS score and brain water content were significantly positively correlated with serum S100 A8/A9 (r = 0.48, P < 0.001; r = 0.63, P < 0.001). In conclusion, the level of serum S100A8/A9 in rats after cardiopulmonary resuscitation is significantly increased, which is positively correlated with the degree of brain injury in rats.