Tyramine and octopamine: Antagonistic modulators of behavior and metabolism

Abstract

The phenolamines tyramine and octopamine are decarboxylation products of the amino acid tyrosine. Although tyramine is the biological precursor of octopamine, both compounds are independent neurotransmitters, acting through various G-protein coupled receptors. Especially, octopamine modulates a plethora of behaviors, peripheral and sense organs. Both compounds are believed to be homologues of their vertebrate counterparts adrenaline and noradrenaline. They modulate behaviors and organs in a coordinated way, which allows the insects to respond to external stimuli with a fine tuned adequate response. As these two phenolamines are the only biogenic amines whose physiological significance is restricted to invertebrates, the attention of pharmacologists was focused on the corresponding receptors, which are still believed to represent promising targets for new insecticides. Recent progress made on all levels of octopamine/tyramine research enabled us to better understand the molecular events underlying the control of complex behaviors.

Reciprocal inhibition between sensory ASH and ASI neurons modulates nociception and avoidance in Caenorhabditis elegans

“…However, our current data are not conclusive enough to exclude the possibility that TA functions in the regulation of the Cu 2 þ -elicited aversive behaviours. Another possible explanation is that TA and OA act antagonistically in response to a Cu 2 þ stimulus as previously suggested 60 . A third hypothesis is that OA biosynthesis in the tdc-1(n3419) II mutant may be not fully blocked.…”

Microcolumn Separation of Amine Metabolites in the Fruit Fly

“…The borate-MEKC-EC method has also been used to examine the Drosophila iav 1 mutant, where quantitative comparison of metabolite and biogenic amine levels between the wild-type fly and the mutated fly have been made in these genetically distinct animals. A single optimized separation of 100 μM standards (10 μM CAT, internal standard) shown with the following peak identification: DA (1), E (2), naOA (3), NE (4), OA (5), na5HT (6), naDA (7), 5-HIAA (8), L-DOPA (9), HVA (10), CAT (11), TA (12), 3-MT (13), 5-HT (14), DOPAC (15). Separations were performed in a 13-μm i.d.…”

Preface: Cellular actions of biogenic amines

“…The following two reports provide detailed information on the responses of a tyramine receptor from Bombyx mori to 2-phenylethylamines and 5-phenyloxazoles (Ozoe et al, 2005, this issue) and of an octopamine receptor from Periplaneta americana to plant essential oils (Enan, 2005, this issue). These findings are important with respect to the limited knowledge of the pharmacological properties of tyramine and octopamine receptors, which have both been discussed as potential insecticide targets (Roeder et al, 2003).…”

“…Compared with mammals, enzymes metabolizing biogenic amines, i.e., monoamine oxidase (MAO) and catechol-O-methyl-transferase (COMT), play a minor role, if any, in the insect nervous system (for a recent review, see Sloley, 2004). Here, the inactivation of biogenic amines is achieved by N-acetylation, N-methylation, and/or O-sulphation (for reviews, see Wright, 1987;Downer, 1990;Roeder et al, 2003). In addition, the β-alanyl conjugation of biogenic amines by Ebony proteins has been suggested to be involved in the inactivation of biogenic amines in Drosophila (Hovemann et al, 1998;Richardt et al, 2003).…”

“…In insects, these small organic compounds act as neurotransmitters, neuromodulators, and neurohormones (for reviews, see : Evans, 1980;Downer, 1990;Roeder, 1994;Baumann, 2001, 2003;Baumann et al, 2003;Roeder et al, 2003). Biogenic amines control endocrine and exocrine secretion (Just and Walz, 1996;Marg et al, 2004), the contraction properties of muscles, the activity of neurons (for a review, see Bicker and Menzel, 1989), and the generation of motor patterns (Claassen and Kammer, 1986).…”