心肺复苏后大鼠脑组织精脒/精胺-N1-乙酰基转移酶2与HIF-1α表达的动态变化规律

Expression correlation between spermidine/spermine-N1-acetyltransferase 2 and hypoxia inducible factor-1α in cerebral cortex of rat after cardiopulmonary resuscitation

目的研究心肺复苏后大鼠脑组织中精脒/精胺-N1-乙酰基转移酶2(spermidine/spermine-N1-acetyltrans-ferase2,SSAT2)与缺氧诱导因子-1α(hypoxia inducible factor 1 alpha,HIF-1α)表达的动态变化规律,分析二者相关性。方法 88只成年SD大鼠随机数字表法分为正常对照组(n=8)、假手术组(n=40)和心肺复苏组(n=40)。其中假手术组和心肺复苏组再分为1、8、24、48、72 h 5个亚组,每亚组8只。采用RT-PCR、Western blot法分别检测脑组织中HIF-1αmRNA和HIF-1α、SSAT2蛋白的表达。结果 SSAT2的表达在复苏后明显降低,1 h[(0.314±0.027),P<0.01]表达最低,随后逐渐升高(P<0.01),至72 h[(0.731±0.024),P>0.05]时回升到正常对照组水平(0.736±0.02),而假手术组SSAT2的表达与正常对照组相比无显著变化(P>0.05)。HIF-1αmRNA的表达在复苏后1 h[(0.245±0.021),P<0.05]时降低,但8 h[(0.430±0.019),P<0.05]时明显增强,后24 h[(0.387±0.018),P<0.05]、48 h[(0.385±0.019),P<0.05]下降,至72 h时回落到正常对照组水平(0.343±0.022);但HIF-1α蛋白在复苏后1 h[(0.755±0.012),P<0.01]显著增高,随后逐渐下降(P<0.01),至72 h[(0.033±0.002),P<0.01]时仅轻度增高,而在正常对照组和假手术组未能检测出HIF-1α表达。SSAT2表达与HIF-1α表达在复苏后72 h内呈负性相关(r=-0.945,P<0.01),SSAT2表达与HIF-1αmRNA表达在复苏后8～48 h呈负相关(r=-0.614,P=0.01)。结论在心肺复苏后一定时间内,大鼠脑组织SSAT2表达减弱,HIF-1αmRNA及蛋白表达增加,两者呈负相关表达,提示SSAT2对HIF-1α蛋白、HIF-1αmRNA可能起负性调节作用。

Objective To study the expression correlation between spermidine/spermine-N1-acetyltransferase 2（SSAT2） and hypoxia inducible factor-1α（HIF-1α） in the cerebral cortex of rat after cardiopulmonary resuscitation（CPR）.Methods Eighty-eight adult SD rats were randomized into a control group（n=8）,a sham operation group（n=40）,and a CPR group（n=40）.The sham operation group and CPR group each were further divided into 1,8,24,48,and 72 h subgroups（n=8）.In the CPR group,cardiac arrest（CA） was induced by bolus injection of 4℃ 10% potassium chloride solution through the external jugular vein,and cardiopulmonary resuscitation began 5 min after CA.The mRNA expression of HIF-1α and the protein expression of SSAT2 and HIF-1α in cerebral cortex were measured by RT-PCR and western blotting in 1,8,24,48,and 72 h after return of spontaneous circulation（ROSC）.Results The protein expression of SSAT2 in the CPR group decreased markedly in 1 h after ROSC（0.314±0.027,P0.01）,then increased gradually,and returned to the normal level in 72 h after ROSC（0.731±0.024,P0.05）,and that in the sham operation group showed no significant difference from that in the control group（0.736±0.02）（P0.05）.The mRNA expression of HIF-1α in the CPR group decreased in 1 h after ROSC（0.245±0.021,P0.05）,reached the peak level in 8 h after ROSC（0.430±0.019,P0.05）,decreased in 24 and 48 h after ROSC（0.387±0.018,P0.05;0.385±0.019,P0.05）,and returned to the normal level in 72 h after ROSC（0.343±0.022,P0.05）.The protein expression of HIF-1α in the CPR group increased significantly in 1 h after ROSC（0.755±0.012,P0.01）,then decreased gradually,and was weakly positive in 72 h after ROSC（0.033±0.002,P0.01）.The protein expression of HIF-1α was not detected in the control group and sham operation group.The protein expression of SSAT2 was negatively correlated with the protein expression of HIF-1α within 72 h after ROSC（r=-0.945,P0.01） and the mRNA expression of HIF-1α between in 8 h and 48 h after ROSC（r=-0.614,P=0.01）.Conclusion The protein expression of SSAT2 decreases after ROSC,while the mRNA and protein expression of HIF-1α increases,indicating that SSAT2 may regulate the mRNA and protein expression of HIF-1α negatively.