PeaTAR1B: Characterization of a Second Type 1 Tyramine Receptor of the American Cockroach, Periplaneta americana.

Wolfgang Blenau,Arnd Baumann,Sabine Balfanz

doi:10.3390/ijms18112279

Abstract

The catecholamines norepinephrine and epinephrine regulate important physiological functions in vertebrates. In insects; these neuroactive substances are functionally replaced by the phenolamines octopamine and tyramine. Phenolamines activate specific guanine nucleotide-binding (G) protein-coupled receptors (GPCRs). Type 1 tyramine receptors are better activated by tyramine than by octopamine. In contrast; type 2 tyramine receptors are almost exclusively activated by tyramine. Functionally; activation of type 1 tyramine receptors leads to a decrease in the intracellular concentration of cAMP ([cAMP]i) whereas type 2 tyramine receptors can mediate Ca2+ signals or both Ca2+ signals and effects on [cAMP]i. Here; we report that the American cockroach (Periplaneta americana) expresses a second type 1 tyramine receptor (PeaTAR1B) in addition to PeaTAR1A (previously called PeaTYR1). When heterologously expressed in flpTM cells; activation of PeaTAR1B by tyramine leads to a concentration-dependent decrease in [cAMP]i. Its activity can be blocked by a series of established antagonists. The functional characterization of two type 1 tyramine receptors from P. americana; PeaTAR1A and PeaTAR1B; which respond to tyramine by changing cAMP levels; is a major step towards understanding the actions of tyramine in cockroach physiology and behavior; particularly in comparison to the effects of octopamine.

Highlights

The American cockroach, Periplaneta americana, is an established model organism in neurobiological, physiological, and toxicological studies [1,2,3]
Because of its generous size and simple animal maintenance, P. americana is well suited for studying the morphology, physiology, and pharmacology of the insect nervous system
Using degenerate oligonucleotide primers for highly conserved GPCR transmembrane (TM) regions 6 and 7, we amplified a cDNA fragment of 113 bp from P. americana brain cDNA coding for a putative tyramine receptor

Summary

Introduction

The American cockroach, Periplaneta americana, is an established model organism in neurobiological, physiological, and toxicological studies [1,2,3]. P. americana can infest any type of buildings and is frequently found in basements and sewers. They feed on human and pet food and can leave an offensive odor. They can passively transport pathogenic bacteria, such as Salmonella, on their body surfaces, in environments such as hospitals [21,22]. P. americana must be considered as an insect pest of significant public health importance and cockroach populations may be controlled using insecticides

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