Characterization of a Dopamine D1 Receptor from Apis mellifera: Cloning, Functional Expression, Pharmacology, and mRNA Localization in the Brain

The neurotransmitter dopamine is an important regulator of physiological and behavioral functions in both vertebrates and invertebrates. We have isolated a homologue of the vertebrate dopamine D1 receptor subfamily from the honeybee Apis mellifera. [3H]Lysergic acid diethylamide specifically binds to the heterologously expressed receptor with K(D) approximately 5 nM. Dopaminergic receptor ligands compete for this high-affinity binding, with the following order of potency: R(+)-lisuride > chlorpromazine = cis(Z)-flupentixol > dopamine > S(+)-butaclamol > R(+)-SCH 23390 > haloperidol. Activation of the heterologously expressed receptor of Apis mellifera leads to cyclic AMP production. Receptor mRNA is expressed in perikarya of different brain neuropils, including those of mushroom body intrinsic neurons. These results suggest that this dopamine receptor is involved in signal processing of visual and olfactory information in the honeybee.