Characterization of a serotonin receptor endogenous to frog melanophores

The response of a cell line of Xenopus laevis melanophores to serotonin was examined. Serotonin increased intracellular levels of cAMP and induced pigment dispersion in the cells. The responses depended on both the concentration of serotonin applied and on the time for which the cells were exposed to serotonin. Using a recently described, microtiter-plate-based bioassay, a series of serotonin receptor ligands were evaluated as agonists or antagonists at the melanophore serotonin receptor. The pharmacological profile suggests the presence of a receptor which shares some properties with but appears different from other previously described serotonin receptors.