急性肺损伤大鼠肺组织β和β_2受体及β_2受体mRNA表达的变化

Changes of beta, beta-2-adrenergic receptor and beta-2-adrenergic receptor mRNA expression in lung tissue during endotoxin-induced acute lung injury in rats

目的：观察急性肺损伤（ＡＬＩ）大鼠肺组织β、β２受体和β２受体ｍＲＮＡ含量的变化，探讨上述变化与ＡＬＩ的关系及β２受体变化可能的分子机制。方法：静注内毒素复制大鼠ＡＬＩ模型，肺组织β、β２受体及β２受体ｍＲＮＡ含量，分别用放射性配基结合分析法和斑点杂交技术测定。结果：静注内毒素后１、４、６ｈ，大鼠肺组织β和β２受体的最大结合容量（Ｂｍａｘ）均明显低于正常对照组（Ｐ＜０．０１），尤以β２受体为甚；静注内毒素后４及６小时，大鼠肺组织β２受体ｍＲＮＡ含量分别下降至正常对照组的７６４％±１９６％（Ｐ＜０．０１）和５２８％±２０４％（Ｐ＜０．０１）。结论：肺组织β受体数目的减少在ＡＬＩ发生发展中可能起一定的作用，β２受体数目的减少可能与ＡＬＩ关系更密切；β２受体ｍＲＮＡ含量的减少可能是ＡＬＩ后一定阶段肺组织β２受体数目减少的原因之一。

AIM:To observe the changes of beta, beta-2-adrenergic receptors(β-AR,β 2-AR) and beta-2-adrenergic receptor mRNA expression in lung tissue of rat with acute lung injurg (ALI), in order to explore the molecular mechanism of changes of beta-2-adrenergic receptor and the relation between above changes and ALI.METHODS:The model of ALI in rat was established by intravonous injection of E. coli endotoxin (ET). β-AR and β 2-AR were measured by radioligand binding assay with -dihydroalprenolol. The expression of β 2-AR mRNA of lung tissue in rat was anlysed by dot blot hybridization. RESULTS:(1) The maximal capacity of the receptor (Bmax) of both β-AR and β 2-AR in the lung tissue decreased significantly at the 1st, 4th and 6th hours after injection of ET. The density of β 2-AR was much lower than that of β-AR.(2) The expression of β 2-AR mRNA in lung tissue decreased to 76.4% and 52.8% of the level in control group at the 4th and 6th hours respectively after injection.CONCLUSIONS:(1)The decrease of density of β-AR in lung tissue may play some role in the development of ALI. The reduction of β 2-AR may be more important than that of β-AR in develepment of ALI. (2) The decrease of β 2-AR mRNA expression may be one of the reasons of reduction of lung tissue β 2-AR in ALI.