CHARACTERIZATION OF INSECT NEURONAL OCTOPAMINE RECEPTORS (OA3 RECEPTORS)

Octopamine receptors in the nervous tissue of insects were investigate d using a ligand-receptor assay with [H-3]NC-5Z or [H-3]octopamine as the radioligands. Both ligands recognized a homogenous class of bindin g sites with the properties of an octopamine receptor. This receptor h as been characterized pharmacologically. Both high-affinity agonists ( e.g. NC 7, K1 = 0.3 nM) and antagonists (e.g. maroxepine, K1 = 1.02 nM ) were investigated. The neuronal octopamine receptor belongs to a rec eptor class that can easily be distinguished from peripheral octopamin e receptors. Initial investigations of the localization of octopamine receptors within the insect nervous tissue show the greatest receptor density in the optic lobes.