Aminergic receptors in Drosophila melanogaster: properties of [3H]dihydroergocryptine binding sites.

[3H]Dihydroergocryptine ([3H]DHE) binds to a particulate preparation from Drosophila melanogaster heads at a level of 2.4 +/- 0.4 pmol/mg protein, with an apparent dissociation constant of 2.0 +/- 0.5 nM. The binding sites are inactivated by heat, pronase treatment, and sulfhydryl and disulfide reagents. [3H]DHE binding is inhibited by low concentrations of serotonergic and alpha-adrenergic ligands. The specificity of the binding sites, as revealed by displacement studies, differs from that of [3H]DHE binding sites in various vertebrate tissues. The [3H]DHE binding sites may correspond to serotonergic receptors, and possibly, to additional classes of receptors for putative neurotransmitters in Drosophila.