Palazzi E, Ceppi E, Guglielmetti F, Catozzi L, Amoroso D, Groppetti A
Department of Medical Pharmacology "Emilio Trabucchi," University of Milano, Milano, Italy.
J Neurochem. 1996 Jul;67(1):138-44. doi: 10.1046/j.1471-4159.1996.67010138.x.
Radioligand binding assays and functional experiments revealed that the SK-N-BE neuroblastoma cell line expresses a similar ratio of mu- and delta-opioid receptors, both negatively coupled to adenylyl cyclase through pertussis toxin-sensitive G proteins. Our findings also indicate that some functional interaction occurred between the two opioid subtypes; in fact, long-term exposure to [D-Ala2-N-methyl-Phe4-Gly-ol5]enkephalin (DAMGO), a mu-selective agonist, sensitized the functional response of the delta-selective agonist but not vice versa. It is interesting that in acute interaction experiments, we observed a shift to the right of the concentration-effect curve of either DAMGO or [D-Pen2,5]enkephalin (DPDPE), a delta-selective agonist, as a result of DPDPE or DAMGO administration, respectively. In addition, low doses of naloxone, an antagonist selective for mu receptors, increased the inhibitory effect [D-Ala2-D-Met5]enkephalinamide (DAME), a mixed mu/delta agonist, on adenylyl cyclase activity. Taken overall, these data support the hypothesis of the existence of a cross talk between mu and delta receptors in the SK-N-BE cell line.
放射性配体结合试验和功能实验表明，SK-N-BE神经母细胞瘤细胞系表达的μ型和δ型阿片受体比例相似，二者均通过百日咳毒素敏感的G蛋白与腺苷酸环化酶负偶联。我们的研究结果还表明，两种阿片类受体亚型之间存在一些功能相互作用；事实上，长期暴露于μ型选择性激动剂[D-Ala2-N-甲基-Phe4-Gly-ol5]脑啡肽（DAMGO）会使δ型选择性激动剂的功能反应敏感化，但反之则不然。有趣的是，在急性相互作用实验中，我们分别观察到，由于给予DPDPE或DAMGO，DAMGO或δ型选择性激动剂[D-Pen2,5]脑啡肽（DPDPE）的浓度效应曲线向右移动。此外，低剂量的μ型受体选择性拮抗剂纳洛酮增强了μ/δ混合型激动剂[D-Ala2-D-Met5]脑啡肽酰胺（DAME）对腺苷酸环化酶活性的抑制作用。总体而言，这些数据支持了SK-N-BE细胞系中μ型和δ型受体之间存在相互作用的假说。
