Mapping the melatonin receptor. 7. Subtype selective ligands based on beta-substituted N-acyl-5-methoxytryptamines and beta-substituted N-acyl-5-methoxy-1-methyltryptamines

摘要

A series of beta-substituted and beta,beta-disubstituted N-acyl 5-methoxy-1-methyltryptamines and 5-methoxy-tryptamines have been prepared as melatonin analogues to investigate the nature of the binding site of the melatonin receptor. The affinity of analogues was determined in a radioligand binding assay using cloned human MT1 and MT2 receptor subtypes expressed in NIH 3T3 cells. Agonist and antagonist potency of all analogues was measured using the pigment aggregation response of a clonal line of Xenopus laevis melanophores. beta-Methylmelatonin ( 17a) and beta,beta-dimethylmelatonin ( 17b), though showing a slight decrease in binding at human receptors, show an increase in potency on Xenopus. N-Butanoyl 5-methoxy-1-methyl-beta,beta-trimethylenetryptamine ( 12c) is an antagonist at human MT1 receptors but an agonist at MT2, while N-butanoyl 5-methoxy-1-methyl-beta,beta-tetramethylenetryptamine ( 13c) is an antagonist at MT1 but had no action at MT2 and is one of the first examples of an MT1 selective antagonist.