Octopaminergic antagonists

We have attempted to characterize this response further and to define its pharmacology and its utility as a rapid vivo assay for octopaminergic agents, particularly for actions on the CNS (31). The response to OA is specific in that none of the other putative neuroeffectors tested induced a comparable effect with the exceptions of NE and dopamine, both of which are known to have octopaminergic actions of their own. The response to OA was blocked by typical octopaminergic antagonists such as phentolamine, metoclopramide and mianserin (Table II). 

Table II. Potency of Octopamine and DCDM in the Crayfish Behavioral Assay and the Effect of Selected Octopaminergic Antagonists on their Action.

Hirashima, A., Kuwano, E. and Eto, M. (2003) Comparative receptor surface analysis of octopaminergic antagonists for the locust neuronal octopamine receptor. Comp. Biol. Chem., 27, 531-540. 

The only aspect of octopaminergic transmission for which a relatively large amount of structure-activity data is available relates to the properties of OA-receptors themselves. Agonists that stimulate these systems and antagonists that block them, are known and such compounds exist in several structural groups. The three major groups of agonists currently identified are phenylethylamines amidines and imidazolines. 

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