The effect of insulin on the expressions of Bcl-2, Bax mRNA and hippocampus neuronal apoptosis in rats after cardiopulmonary resuscitation

Objective To explore the effects of intraventricular administration of insulin on the expressions of Bcl-2,Bax mRNA and neuronal hippocampus apoptosis in rats after cardiopulmonary resuscitation (CPR).Methods This experiment was implemented in the animal Laboratory center of Xuanwu Hospital of Capital Medical University.Thirty male SD rats were randomly (random number)divided into three groups:control group (n=6),CPR group (n=12),insulin treated group ( n =12).CPR was performed at 6 minutes after ventricular fibrillation induced by transesophageal overdrive pacing.Resuscitation procedures lasted until restoration of spontaneous circulation (ROSC).ROSC was defined as the recovery of the supraventricular heart rates and the increase of mean arterial pressure (MAP) ＞ 60mmHg for more than 10 minutes.Ten minutes after ROSC in rats,12.5 μL ( 1 U) regular insulin was injected into the left ventricle in the insulin group,and 12.5 μL isotonic saline was injected the control and CPR groups at least 10 minutes.Real-time PCR was used to observe the expressions of Bcl-2,Bax mRNA in hippocampus CAI after reperfusion 24 h and 72 h.TUNEL staining was used to observe the neuronal apoptosis in all groups after reperfusion 7 days.Blood glucose was monitored in rats before and after CPR.Results ① The Bcl-2mRNA in insulin groups were significantly higher than those in the CPR group after 24 h and 72 h (P ＜0.01 ).The expression of Bcl-2 mRNA in 24 h insulin group were significantly higher than those in 72 h insulin group ( P ＜ 0.01 ) ; There were no significantly different in the Bax mRNA between insulin groups and the CPR and the control group after 24 h and 72 h ( P ＞ 0.05 ) ; ②After CPR 7 d,the apoptotic neurons of hippocampal CA1 area in the CPR group ( 124.75 ± 17.35 ) were significantly higher than those in the control group (5.12 ± 3.26) ( P ＜ 0.01 ) and the insulin group (92.79 ± 7.35 )(P ＜0.01 ); the apoptotic neurons in the insulin group were higher than those in the control group (P ＜0.0l ),and the differences were statistically significant.③There were no significant difference in venous blood glucose in the CPR and insulin groups (P ＞ 0.05).Conclusions Insulin may regulate Bcl-2mRNA expression in hippocampus,inhibit neuronal apoptosis and protect neurons after CPR in rats. Key words: Cardiopulmonary resuscitation (CPR);  Insulin;  Bcl-2 mRNA;  Bax mRNA; Apoptosis;  Rat;  Hippocampus;  Neurological protection