Archives of Insect Biochemistry and Physiology 2010-02-01

Pharmacological characterization of a Bombyx mori alpha-adrenergic-like octopamine receptor stably expressed in a mammalian cell line.

Jia Huang, Tomohiro Hamasaki, Yoshihisa Ozoe

Index: Arch. Insect Biochem. Physiol. 73(2) , 74-86, (2010)

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Abstract

Series of agonists and antagonists were examined for their actions on a Bombyx morialpha-adrenergic-like octopamine receptor (OAR) stably expressed in HEK-293 cells. The rank order of potency of the agonists was clonidine>naphazoline>tolazoline in Ca(2+) mobilization assays, and that of the antagonists was chlorpromazine>yohimbine. These findings suggest that the B. mori OAR is more closely related to the class-1 OAR in the intact tissue than to the other classes. N'-(4-Chloro-o-tolyl)-N-methylformamidine (DMCDM) and 2-(2,6-diethylphenylimino)imidazolidine (NC-5) elevated the intracellular calcium concentration ([Ca(2+)](i)) with EC(50)s of 92.8 microM and 15.2 nM, respectively. DMCDM and NC-5 led to increases in intracellular cAMP concentration ([cAMP](i)) with EC(50)s of 234 nM and 125 nM, respectively. The difference in DMCDM potencies between the cAMP and Ca(2+) assays might be due to "functional selectivity." The Ca(2+) and cAMP assay results for DMCDM suggest that the elevation of [cAMP](i), but not that of [Ca(2+)](i), might account for the insecticidal effect of formamidine insecticides.2009 Wiley Periodicals, Inc.