Effect of hypothermia on expression of cold-inducible RNA-binding protein after cardiopulmonary resuscitation in a rat model of cardiac arrest

Abstract

Objective To evaluate the effect of hypothermia on the expression of cold-inducible RNA-binding protein (CIRP) after cardiopulmonary resuscitation (CPR) in a rat model of cardiac arrest. Methods Ninety pathogen-free male Sprague-Dawley rats, weighing 280-320 g, were randomly divided into 3 groups (n=30 each) using a random number table: sham operation group (group Sham), cardiac arrest-CPR group (group CPR), and hypothermia group (group H). Group Sham underwent only cannulation of the artery and vein and tracheal intubation.In group CPR, cardiac arrest was induced by electric stimulation via the esophagus, and then CPR was performed.In group H, the rectal temperature was cooled down to 32-34 ℃ within 15 min by putting rats on the ice bags immediately after recovery of spontaneous circulation (ROSC), and maintained at this level for 6 h, while the rectal temperature was maintained at 36-37 ℃ in the other groups.Neurological deficit score (NDS) was evaluated at 24 and 72 h after ROSC, and the rats were then sacrificed.The hippocampus was removed for examination of the pathological changes of pyramidal cells in the hippocampal CA1 region (using hematoxylin and eosin staining), and for determination of the expression of CIRP mRNA and protein (using fluorescent quantitative real-time reverse transcriptase-polymerase chain reaction or Western blot). Results Compared with group Sham, NDS score was significantly decreased, and the expression of CIRP mRNA and protein was up-regulated at 24 and 72 h after ROSC in CPR and H groups (P<0.05). Compared with group CPR, NDS score was significantly increased at 72 h after ROSC, and the expression of CIRP mRNA and protein was up-regulated at 24 and 72 h after ROSC in group H (P<0.05). Conclusion Hypothermia can effectively reduce cerebral ischemia-reperfusion injury and improve neurological function after CPR, and the mechanism is probably related to up-regulation of CIRP expression in a rat model of cardiac arrest. Key words: Hypothermia, induced; Heart arrest, induced; Cardiopulmonary resuscitation; Carrier proteins; Hippocampus