The Screen-Well® histaminergic and melatonin ligands plate contains 41 ligands including endogenous neurotransmitters, agonists, antagonists, and marketed drugs. The library is ideal for screening or identifying recombinant orphan G protein coupled receptors, target validation, secondary screening, assay development, and other pharmacological applications. The Histaminergic and Melatonin Ligands plate is 1 plate of the larger neurotransmitter library which contains over 680 ligands.