In addition to intrinsic antioxidant activities, melatonin evokes its effects through the G protein-coupled receptors MT1A (MT1) and MT1B (MT2). Luzindole is a melatonin receptor antagonist that preferentially targets MT1B over MT1A (Ki values are = 10-27 and 158-513 nM, respectively). Luzindole is used both in vitro and in vivo to evaluate the roles of melatonin receptor signaling in diverse pathways, including circadian rhythms, animal behavior, and melanophore response.
