title: Larvae of the small white butterfly, Pieris rapae, express a novel serotonin receptor.
abstract: The biogenic amine serotonin (5-hydroxytryptamine, 5-HT) is a neurotransmitter in vertebrates and invertebrates. It acts in regulation and modulation of many physiological and behavioral processes through G-protein-coupled receptors. Five 5-HT receptor subtypes have been reported in Drosophila that share high similarity with mammalian 5-HT1A, 5-HT1B, 5-HT2A, 5-HT2B, and 5-HT7 receptors. We isolated a cDNA (Pr5-HT8 ) from larval Pieris rapae, which shares relatively low similarity to the known 5-HT receptor classes. After heterologous expression in HEK293 cells, Pr5-HT8 mediated increased [Ca(2+)]i in response to low concentrations (< 10 nM) of 5-HT. The receptor did not affect [cAMP]i even at high concentrations (> 10 μM) of 5-HT. Dopamine, octopamine, and tyramine did not influence receptor signaling. Pr5-HT8 was also activated by various 5-HT receptor agonists including 5-methoxytryptamine, (±)-8-Hydroxy-2-(dipropylamino) tetralin, and 5-carboxamidotryptamine. Methiothepin, a non-selective 5-HT receptor antagonist, activated Pr5-HT8 . WAY 10635, a 5-HT1A antagonist, but not SB-269970, SB-216641, or RS-127445, inhibited 5-HT-induced [Ca(2+)]i increases. We infer that Pr5-HT8 represents the first recognized member of a novel 5-HT receptor class with a unique pharmacological profile. We found orthologs of Pr5-HT8 in some insect pests and vectors such as beetles and mosquitoes, but not in the genomes of honeybee or parasitoid wasps. This is likely to be an invertebrate-specific receptor because there were no similar receptors in mammals. We isolated a cDNA (Pr5-HT8) from larval Pieris rapae, which shares relatively low similarity to the known GPCRs. After heterologous expression in HEK293 cells, Pr5-HT8 mediated increased [Ca(2+)]i in response to low concentrations (< 10 nM) of 5-HT and various 5-HT receptor agonists. We found orthologs of Pr5-HT8 in some insect pests and vectors such as beetles and mosquitoes, but not in the genomes of honeybee, parasitoid wasps, or mammals.
authors.affiliation: State Key Laboratory of Rice Biology & Key Laboratory of Agricultural Entomology of Ministry of Agriculture, Institute of Insect Sciences, Zhejiang University, Hangzhou, China.
authors.forename: Yi-Xiang
authors.initials: YX
authors.lastname: Qi
authors.forename: Ren-Ying
authors.initials: RY
authors.lastname: Xia
authors.forename: Ya-Su
authors.initials: YS
authors.lastname: Wu
authors.forename: David
authors.initials: D
authors.lastname: Stanley
authors.forename: Jia
authors.initials: J
authors.lastname: Huang
authors.forename: Gong-Yin
authors.initials: GY
authors.lastname: Ye
mesh_terms: D000818:Animals; D001516:Bees; D001549:Benzamides / Q000494:pharmacology*; D002080:Butterflies; D002478:Cells, Cultured; D007814:Larva / Q000187:drug effects / Q000378:metabolism; D008719:Methiothepin / Q000494:pharmacology; D011985:Receptors, Serotonin / Q000187:drug effects*; D012701:Serotonin / Q000378:metabolism*; D012702:Serotonin Antagonists / Q000494:pharmacology; D017366:Serotonin Receptor Agonists / Q000494:pharmacology
chemical_list: D001549:Benzamides; D011985:Receptors, Serotonin; D012702:Serotonin Antagonists; D017366:Serotonin Receptor Agonists; D012701:Serotonin; D008719:Methiothepin
keywords: 5-hydroxytryptamine; GPCR; insecticide; neurotransmitter; pharmacology; serotonin