Molecular and pharmacological analysis of an octopamine receptor from american cockroach and fruit fly in response to plant essential oils

Abstract

Octopamine receptors from American cockroach, Periplaneta americana (Pa oa1), and fruit fly, Drosophila melanogaster (OAMB), were cloned and permanently expressed in HEK-293 cells, and found to activate adenylate cyclase activity and increase [Ca2+]i levels through G-protein coupled receptor signaling pathways. Sequencing information (GenBank accession number AY333178) and functional data of Pa oa1 were recently published. Saturation binding analysis with 3H-yohimbine was performed with Pa oa(1) and OAMB expressed in COS-7 cells. The K(d) values were determined to be 28.4 and 43.0 nM, respectively. B(max) was determined to be 11.8 and 8.04 pmol receptor/mg protein, respectively. Competitive binding data using cell membranes expressing either OAMB or Pa oa1 demonstrated significantly decreased binding activity in binding assays performed in the presence of plant essential oils, eugenol, cinnamic alcohol, and trans-anethole. Eugenol decreased cAMP level in HEK-293 cells expressing Pa oa1, but trans-anethole increased cAMP in HEK-293 cells expressing OAMB. All three chemicals increased [Ca2+]i level in both cell models. Toxicity data against fruit flies and American cockroaches demonstrated species differences in response to treatment with tested plant essential oils. The toxicity of tested chemicals against wild type and octopamine mutant (iav) fly strains suggested that an octopamine receptor mediates the toxicity of cinnamic alcohol, eugenol, trans-antehole, and 2-phenethyl propionate against fruit flies. Collectively, the data suggest a correlation between cellular changes induced by tested plant essential oils and their toxicity against fruit fly and American cockroach.

Quantitative Structure-Activity Relationships (QSARs) of Monoterpenoids at an Expressed American Cockroach Octopamine Receptor

“…It has previously been suggested that octopamine receptor activity is enhanced with the presence of an oxygen atom (13). However, p-cymene, which lacks an oxygen substituent, showed a significant result in our assay, but was not as effective as other monoterpenoids that contained an oxygen substituent.…”

“…Various studies have indicated that monoterpenoids may have several mechanisms of action. Mechanisms that have been reported include: inhibition of acetylcholinesterase (5,6), binding at the GABA receptor (7)(8)(9)(10)(11), binding at the nicotinic acetylcholine receptor (12), the octopamine receptor (13,14), and the tyramine receptor (15). Previous studies have also described quantitative structure-activity relationships (QSARs) to describe the toxicity of monoterpenoids and their interaction at the GABA receptor (11).…”

Essential oils and their components as an alternative in the control of mosquito vectors of disease

“…Está presente en el sistema nervioso de todos los insectos y actúa como neurotransmisor, neurohormona y neuromodulador (147). Otra función que se le atribuye está relacionada con el comportamiento activo o de "atención", por lo que se ha sugerido que forma parte de un sistema general que prepara al insecto para su actividad vigorosa.…”

“…Algunos autores han planteado que los componentes de los aceites esenciales actúan bloqueando los receptores de la octopamina (131) y produciendo alteraciones neurológicas graves con efectos nocivos para los insectos. El eugenol y el timol, por ejemplo, pueden funcionar mediante el bloqueo de estos receptores (147,148). Con el acoplamiento molecular se ha demostrado que el carvacrol, el eugenol y el eucaliptol son capaces de interactuar en el sitio de unión del receptor oamb de la octopamina de Ae.…”

Preface: Cellular actions of biogenic amines

“…Thus, grc3 most probably encodes a second tyramine receptor expressed in the locust (Molaei et al, 2005, this issue). 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).…”