地塞米松对内毒素血症幼年大鼠心肌肌动蛋白及其mRNA表达的影响

Effect of dexamethasone on expressions of alpha-sarcomeric actin and its mRNA in myocardium of rats with endotoxemia

目的：通过观察地塞米松（Dex）对内毒素血症幼年大鼠心肌肌动蛋白（α-SA）及其mRNA表达的影响,探讨Dex对内毒素血症大鼠心肌收缩功能的保护途径.方法：选健康18 d Wistar大鼠121只,按腹腔注射药物不同分成：生理盐水对照组,内毒素（LPS）组、Dex组,各组于加LPS后2,4,6,24及72 h分别将大鼠断头分离心脏,RT-PCR方法测定α-SA mRNA表达水平,用免疫组化方法测定α-SA.结果：LPS和Dex组各时点α-SA及其mRNA表达均较对照组明显减弱（P＜0.01）;Dex组最低点与LPS组一致在6～24 h,但明显高于LPS组（P＜0.01）.结论：α-SA及其mRNA表达在内毒素血症时明显受到抑制,心肌收缩功能受损;Dex可减轻LPS对d-SA及其mRNA表达的抑制作用.

Objective： To study the effect of dexamethasone （Dex） on the expressions of alpha-sarcomeric actin （α-SA） and α-SA mRNA in myocardium of rats with endotoxemla, and to explore the protective effect of Dex on the systolic function of rat myocardium. Methods： We randomly divided 121 Wistar rats aged 18 days into 3 groups ： saline control group （ intraperitoneal injection of saline of 1 ml/kg; n = 11 ）, lipopolysaccharide （LPS） group （ intraperitoneal injection of LPS of 4 mg/kg; n = 55 ）, and Dex group （ intraperitoneal injection of LPS of 4 mg/kg and Dex of 5 mg/kg; n =55）. The rats in each group were killed 2, 4, 6, 24, and 72 hours after receiving LPS, respectively. The expressions of α-SA and α-SA mRNA in the myocardium were detected by using reverse transcription polymerase chain reaction and immunohistochemistry assay, respectively. Results： The expressions of α-SA and α-SA mRNA in LPS and Dex groups were significantly lower than those in control group at each time point （ P 〈 0.01 ）, and in Dex group they were significantly higher than those in LPS group at hour 6 and hour 24 （ P 〈0.01）. Conclusion： The expressions of α-SA and α-SA mRNA were inhibited and the systolic function of myocardium was damaged in rats with LPS-induced endotoxemia. Dex could relieve the inhibitory effect of LPS on the expressions of α-SA and α-SA mRNA.