Characterization of a β-adrenergic-like octopamine receptor from the rice stem borer (Chilo suppressalis).
Octopamine, the invertebrate counterpart of adrenaline and noradrenaline, plays a key role in regulation of many physiological and behavioral processes in insects. It modulates these functions through binding to specific octopamine receptors, which are typical rhodopsin-like G-protein coupled receptors. A cDNA encoding a seven-transmembrane receptor was cloned from the nerve cord of the rice stem borer, Chilo suppressalis, viz. CsOA2B2, which shares high sequence similarity to CG6989, a Drosophila β-adrenergic-like octopamine receptor (DmOctβ2R). We generated an HEK-293 cell line that stably expresses CsOA2B2 in order to examine the functional and pharmacological properties of this receptor. Activation of CsOA2B2 by octopamine increased the production of cAMP in a dose-dependent manner (EC(50)=2.33 nmol l(-1)), with a maximum response at 100 nmol l(-1). Tyramine also activated the receptor but with much less potency than octopamine. Dopamine and serotonin had marginal effects on cAMP production. Using a series of known agonists and antagonists for octopamine receptors, we observed a rather unique pharmacological profile for CsOA2B2 through measurements of cAMP. The rank order of potency of the agonists was naphazoline > clonidine. The activated effect of octopamine is abolished by co-incubation with phentolamine, mianserin or chlorpromazine. Using in vivo pharmacology, CsOA2B2 antagonists mianserin and phentolamine impaired the motor ability of individual rice stem borers. The results of the present study are important for a better functional understanding of this receptor as well as for practical applications in the development of environmentally sustainable pesticides.
State Key Laboratory of Rice Biology and Key Laboratory of Agricultural Entomology of Ministry of Agriculture, Institute of Insect Sciences, Zhejiang University, Hangzhou 310058,  China.
Shun-Fan
SF
Wu
Yao
Y
Yao
Jia
J
Huang
Gong-Yin
GY
Ye
D000595:Amino Acid Sequence; D000818:Animals; D001522:Behavior, Animal / Q000502:physiology; D001681:Biological Assay; D003001:Cloning, Molecular; D000242:Cyclic AMP / Q000378:metabolism; D020869:Gene Expression Profiling; D005786:Gene Expression Regulation; D057809:HEK293 Cells; D006801:Humans; D008024:Ligands; D008124:Locomotion / Q000502:physiology; D008969:Molecular Sequence Data; D009036:Moths / Q000235:genetics / Q000378:metabolism*; D012275:Oryza / Q000469:parasitology*; D010802:Phylogeny; D018547:Plant Stems / Q000469:parasitology*; D011943:Receptors, Adrenergic, beta / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D017982:Receptors, Biogenic Amine / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D020133:Reverse Transcriptase Polymerase Chain Reaction; D016415:Sequence Alignment; D017386:Sequence Homology, Amino Acid
D008024:Ligands; D011943:Receptors, Adrenergic, beta; D017982:Receptors, Biogenic Amine; C027604:norsynephrine receptor; D000242:Cyclic AMP