Wang Y Y, Aghajanian G K
Department of Pharmacology, Yale University, School of Medicine, New Haven, CT 06508.
Brain Res. 1987 Dec 15;436(2):396-401. doi: 10.1016/0006-8993(87)91687-8.
The hyperpolarizing effect of morphine on locus coeruleus (LC) neurons, recorded with standard intracellular electrodes, was blocked in brain slices from rats pretreated with pertussis toxin, an inactivator of certain G proteins. In the same slices, when electrodes contained the hydrolysis-resistant GTP analog GTP gamma S, the ability of morphine to rapidly hyperpolarize LC neurons was restored and responses were similar in magnitude to those in control slices. We conclude that there is sufficient residual coupling between opiate receptors and G proteins after pertussis toxin treatment to allow the agonist to be effective when the hydrolysis-resistant GTP analog GTP gamma S is present.
用标准细胞内电极记录时，吗啡对大鼠蓝斑（LC）神经元的超极化作用，在用百日咳毒素（一种某些G蛋白的失活剂）预处理的大鼠脑片中被阻断。在同一切片中，当电极含有抗水解的GTP类似物GTPγS时，吗啡使LC神经元快速超极化的能力得以恢复，且反应幅度与对照切片中的相似。我们得出结论，在百日咳毒素处理后，阿片受体与G蛋白之间存在足够的残余偶联，使得当存在抗水解的GTP类似物GTPγS时激动剂能够发挥作用。
