Characterization of substituted phenylpropylamides as highly selective agonists at the melatonin MT2 receptor.
Melatonin is a widely distributed hormone that regulates several major physiological processes, including the circadian rhythm and seasonal adaptation. The two subtypes of mammalian G protein-coupled melatonin receptors are primarily responsible for mediating the actions of melatonin. Because synthetic melatonin agonists have considerable therapeutic potentials in modulating insomnia and circadian- related sleep disorders, it is highly desirable to develop subtype-selective melatoninergic compounds. The pharmacological potencies of a series of substituted N-[3-(3-methoxyphenyl)propyl] amides towards human melatonin MT(1) and MT(2) receptors were evaluated by the FLIPR high-throughput screening assay, whilst their subtype-selectivity was subsequently verified with ERK phosphorylation and cAMP assays. Structure-activity relationship analysis of highly potent subtype-selective ligands (MT(2) EC(50) 10-90 pM) revealed that a benzyloxyl substituent incorporated at C6 position of the 3-methoxyphenyl ring dramatically enhanced the MT(2) potency and at the same time decreased MT(1) potency. Incorporation of structural moieties conferring the subtype selectivity produced several extremely potent MT(2)-selective ligands. The most potent subtype-selective ligand, 2q had a substantially higher potency for MT(2) receptor than melatonin for elevation of [Ca(2+)]i and inhibition of forskolin-elevated cAMP. Representative MT(2)-selective ligands also induced ERK phosphorylation in both recombinant and native cell lines, and no cross-reactivity to 17 other GPCRs could be detected. These ligands represent invaluable tools for delineating the functional roles of distinct melatonin receptor subtypes and are viable candidates for drug development.
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CHEMICAL CHEMICAL CHEMICAL CHEMICAL GENE-Y GENE-Y GENE-Y GENE-Y GENE-Y GENE-N CHEMICAL GENE-N GENE-N GENE-N GENE-N GENE-Y GENE-Y GENE-N GENE-Y GENE-Y CHEMICAL CHEMICAL CHEMICAL CHEMICAL CHEMICAL CHEMICAL CHEMICAL CHEMICAL
benzyloxyl 3-methoxyphenyl phenylpropylamides melatonin MT(2) MT(1) MT(2) MT(2) receptor MT(2) ERK Melatonin GPCRs melatonin receptor mammalian G protein-coupled melatonin receptors melatonin human melatonin MT(1) MT(2) receptors ERK MT(2) melatonin MT2 receptor melatonin Ca(2+) melatonin melatonin melatonin N-[3-(3-methoxyphenyl)propyl] amides melatonin cAMP