抗氧化剂对内毒素性休克大鼠α_1-肾上腺素能受体mRNA表达的影响

Effects of antioxidant on the gene expression of α_1-adrenergic receptors during endotoxic shock in rats

目的评价抗氧化剂对内毒素性休克大鼠α1-肾上腺素能受体(α1-AR)mRNA表达的影响。方法雄性SD大鼠40只,随机分成5组(n=8):空白对照组(C组);内毒素休克组(LPS组,静脉注射LPS 15 mg·kg-1);异丙酚组(P组,注射LPS后1 h,静脉注射异丙酚10 mg·kg-1,继以10 mg·kg-1· h-1静脉持续泵注4 h);尿酸组(UA组,注射LPS后1 h,腹腔注射UA 200 mg·kg-1);N-乙酰5-甲氧基色胺组(MLT组,注射LPS后1 h,腹腔注射MLT 10 mg·kg-1)。各组大鼠于注射LPS后6h处死,迅速取胸主动脉、下腔静脉、心脏、肝脏、肺脏、肾脏组织。提取各组织的总RNA,逆转录聚合酶链反应(RT- PCR)法检测各组织α1A-AR、α1B-AR和α1D-AR mRNA的表达。结果与C组比较,LPS组α1-AR三种亚型mRNA在胸主动脉、肝脏、肺脏、肾脏组织表达均下降(P<0．05),α1A-AR、α1B-AR mRNA在下腔静脉、心脏组织表达均下降(P<0．05)。与LPS组比较,P组α1A-AR mRNA在肺脏和肾脏组织表达增加(P <0．05),α1B-AR、α1D-AR mRNA在胸主动脉、肝脏、肺脏、肾脏组织表达增加(P<0．05),α1B-AR mRNA 在下腔静脉和心脏组织表达增加(P<0．05);UA组α1A-AR mRNA在肾脏组织表达增加(P<0．05), α1B-AR mRNA在肺脏以外各组织表达均增加(P<0．05),α1D-AR mRNA在胸主动脉、肝脏、肺脏、肾脏组织表达增加(P<0．05);但MLT组α1-AR三种亚型mRNA表达水平变化无统计学意义(P>0．05)。结论内毒素性休克大鼠α1-AR的基因表达普遍下调,抗氧化剂的抗休克作用机制与α1-AR基因表达上调有关。

Objective To investigate the effects of antioxidant on the gene expression of α1-adrenergic receptors （AR） during endotoxic shock.Methods Forty male SD rats weighing 200-250 g were anesthetized with intraperitoneal （i.p.） pentobarbital. The animals kept spontaneous breathing. Femoral artery and vein were cannulated for BP monitoring and drug administration. The animals were randomly divided into 5 groups （ n = 8 each） ： （1） control group; （2） LPS group received LPS 15 mg·kg^-1 i.v. ; （3） LPS＋ propofol group received at lh after LPS a bolus of propofol 10 mg·kg^-1 i.v. followed by continuous infusion of propofol at 10 mg·kg^-1· h^-1 ; （4） LPS ＋ uric acid （UA） group received uric acid 200 mg i.p. 1 h after LPS and （5） LPS ＋ melatonin （MLT） group received MLT 10 mg·kg^- 1 i.p. 1 h after LPS. The animals were killed at 6 h after LPS. Total RNA was extracted from the heart, aorta, vein, lung, liver and kidney, α1A-, α1B-,α1D- AR mRNA and β-actin mRNA were measured using reverse transcription polymerase chain reaction （ RT-PCR）. Results The expression of α1A-AR and α1B-AR mRNA in all the organs and the α1-AR mRNA expression in aorta, liver, lung and kidney were strongly down-regulated in LPS group. In group 3 （LPS ＋ propofol） the expression of α1A-AR mRNA in the lung and kidney, the α1B-AR mRNA expression in all of the organs and α1D-AR mRNA expression in aorta, liver, lung and kidney were significantly increased as compared with LPS group. There was no significant difference in α1-ARmRNA expression between LPS group and LPS ＋ MLT group, The expression of α1A-AR mRNA in kidney, theα1B- AR mRNA expression in all of the organs except the lung and the α1D-AR mRNA expression in aorta, liver, lung and kidney were significantly higher in LPS ＋ UA group than in LPS group. Conclusion Circulatory failure induced by endotoxic shock is related to the down-regulation of α1-AR gene expression. The therapeutic effects of antioxidant on the endotoxic shock is partly due to up-regulation of α1-AR gene expression.