Octopamine, Dopamine, and 5-Hydroxytryptamine in the Cockroach Nervous System

The spectrum of putative neurotransmitters, neurohormones, and neuromodulators that have been identified in the central nervous system (CNS) of cockroaches includes phenolamines, catecholamines, and indolalkylamines. Much research attention has focused on octopamine because of its proposed role as a sympathomimetic effector in insects and the consequent potential of octopaminergic systems as targets for insecticide development. However, octopamine also occurs as a “trace amine” in the CNS of vertebrates and has been implicated in certain neurological, psychiatric, and physiological disorders. ¹ The relatively high concentrations of octopamine that occur in the insect nervous system suggest that these organisms offer a useful model with which to study the biochemistry, pharmacology, and physiology of octopamine. Dopamine and 5-hydroxytryptamine (serotonin), which are involved in several important neural functions in vertebrates, are also present in the insect nervous system. Thus, the cockroach also may have utility as a model for study of some aspects of dopaminergic and serotonergic function. A particular advantage of the insect nervous system as a model for neurobiological research is that the neurons are large, readily identifiable, and accessible.