【摘要】 目的 探讨 RGS4在整体细胞中对阿片受体信号转导途径中腺苷酸环化酶 (AC)活性的影响。方法 采用共转染法将μ-受体、δ-受体和 RGS4基因导入 HEK- 293细胞，受体结合法确定转染效率。用不同浓度的吗啡、 DAMGO和 DPDPE分别激活μ-受体和δ-受体，放射性蛋白竞争结合（非标记底物）法测定 cAMP浓度 。结果 受体被其特异的激动剂激活后，单独转染 μ-受体或δ-受体基因的细胞其 AC活性被抑制，且对激动剂表现出高度的剂量依赖性；空质粒（ pcDNA3）转染的细胞之 AC活性不受各种激动剂影响 ;同时转染 RGS4和 μ-受体基因的细胞其 AC活性虽然也呈现剂量依赖性抑制，但抑制的强度比单独转染μ-受体基因的细胞明显减弱 ; RGS4和 δ-受体基因共转染并不影响δ-受体对 AC活性的抑制。受体结合实验显示 RGS4不影响μ-受体和δ-受体的表达。结论 RGS4能逆转μ-受体对 AC的抑制效应，但对δ-受体却没有相同的作用。这可能反映了不同阿片受体分子机制的差异。更多还原

【Abstract】 Objective To investigate effects of RGS4 on adenylate cyclase(AC) associated withμ- andδ- opioid receptors. Methods The genes ofμ- opioid receptor，δ- opioid receptor， RGS4， and pcDNA3 were introduced into HEK- 293 cells through transfection or co- transfection by DNA- calcium phosphate, and the level of expression of opioid receptors was determined with 3H- diprenorphine binding assay.The activity of AC regulated by opioid receptors was measured with radioactive competitive protein binding assay. ResultsThe AC activity in the cells transfected with onlyμ- orδ- opioid receptor gene was dose- dependently in hibited by both morphine and their specific agonist DAMGO and DPDPE respectively, whereas it was not affected in the cells transfected with pcDNA3 . The DAMGO- and morphine- induced inhibition of AC in the cells transfected with bothμ- opioid receptor and RGS4 genes was significantly weaker than those transfected withμ- opioid receptor gene only. However, the DPDPE and morphine induced similar inhibition of AC in the cells transfected with δ - opioid receptor gene only and those with bothδ- opioid receptor and RGS4 genes. RGS4 did not affect the expression ofμ- andδ- opioid receptors,which was determined by 3H- diprenorphine binding assay. ConclusionsRGS4 reverses theμ- opioid receptor- induced AC inhibition, but has no effect on that induced by δ- opioid receptor.更多还原