RESUMEN
The correct interpretation of data is fundamental to the study of G-protein-coupled receptor pharmacology. Often, new assay technologies are assimilated into the drug discovery environment without full consideration of the data generated. In this study, the authors look at µ-opioid receptor agonists in three different assays: (1) [(35)S]GTPγS binding, (2) inhibition of forskolin-stimulated cAMP production, and (3) ß-arrestin recruitment. Agonist-concentration effect curves were performed before and after treatment with the irreversible antagonist ß-funaltrexamine, and where appropriate, these data were fitted to the operational model of agonism. The Z' value was highest in the ß-arrestin assay, followed by the [(35)S]GTPγS and cAMP assays. The cAMP data fitted well to the operational model, as did the [(35)S]GTPγS data, but the [(35)S]GTPγS assay led to an apparent overestimation of K(A) values. However, in the ß-arrestin assay, data did not fit the operational model, as treatment with ß-funaltrexamine reduced the Emax proportionally to receptor number, with no change in EC(50). In addition, the EC(50) values generated correlated well with affinity values. In conclusion, the ß-arrestin recruitment assay does not fit with traditional pharmacological theory but is of great utility as the EC(50) value generated is a good approximation of affinity.
Asunto(s)
Receptores Opioides mu/agonistas , Arrestina/metabolismo , Línea Celular , AMP Cíclico/metabolismo , Descubrimiento de Drogas/métodos , Guanosina 5'-O-(3-Tiotrifosfato)/metabolismo , Humanos , Cinética , Naltrexona/análogos & derivados , Naltrexona/farmacología , Antagonistas de Narcóticos/farmacología , Unión Proteica/fisiología , Receptores Opioides mu/antagonistas & inhibidores , Receptores Opioides mu/metabolismoRESUMEN
A number of libraries were produced to explore the potential of 2,4-diaminopyridine lead 1. The resulting diaminopyridines proved to be potent and selective delta-opioid receptor agonists. Several rounds of lead optimisation using library chemistry identified compound 17 which went on to show efficacy in an electromyography model of neuropathic pain. The structure-activity relationship of the series against the hERG ion channel proved to be a key selectivity hurdle for the series.