TY - GEN A1 - Troppmann, Britta A1 - Balfanz, Sabine A1 - Baumann, Arnd A1 - Blenau, Wolfgang T1 - Inverse agonist and neutral antagonist actions of synthetic compounds at an insect 5-HT1 receptor N2 - Background and purpose: 5-Hydroxytryptamine (5-HT) has been shown to control and modulate many physiological and behavioural functions in insects. In this study, we report the cloning and pharmacological properties of a 5-HT1 receptor of an insect model for neurobiology, physiology and pharmacology. Experimental approach: A cDNA encoding for the Periplaneta americana 5-HT1 receptor was amplified from brain cDNA. The receptor was stably expressed in HEK 293 cells, and the functional and pharmacological properties were determined in cAMP assays. Receptor distribution was investigated by RT-PCR and by immunocytochemistry using an affinity-purified polyclonal antiserum. Key results: The P. americana 5-HT1 receptor (Pea5-HT1) shares pronounced sequence and functional similarity with mammalian 5-HT1 receptors. Activation with 5-HT reduced adenylyl cyclase activity in a dose-dependent manner. Pea5-HT1 was expressed as a constitutively active receptor with methiothepin acting as a neutral antagonist, and WAY 100635 as an inverse agonist. Receptor mRNA was present in various tissues including brain, salivary glands and midgut. Receptor-specific antibodies showed that the native protein was expressed in a glycosylated form in membrane samples of brain and salivary glands. Conclusions and implications: This study marks the first pharmacological identification of an inverse agonist and a neutral antagonist at an insect 5-HT1 receptor. The results presented here should facilitate further analyses of 5-HT1 receptors in mediating central and peripheral effects of 5-HT in insects. KW - Biogenic amine KW - constitutive activity KW - cellular signalling KW - G-protein-coupled receptor KW - insect Y1 - 2010 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus-44346 ER - TY - GEN A1 - Blenau, Wolfgang A1 - Troppmann, Britta A1 - Walz, Bernd T1 - Pharmacology of serotonin-induced salivary secretion in Periplaneta americana N2 - The acinar salivary gland of the cockroach, Periplaneta americana, is innervated by dopaminergic and serotonergic nerve fibers. Stimulation of the glands by serotonin (5-hydroxytryptamine, 5-HT) results in the production of a protein-rich saliva, whereas stimulation by dopamine results in saliva that is protein-free. Thus, dopamine acts selectively on ion-transporting peripheral cells within the acini, and 5-HT acts on protein-producing central cells. We have investigated the pharmacology of the 5-HT-induced secretory activity of isolated salivary glands of P. americana by testing several 5-HT receptor agonists and antagonists. The effects of 5-HT can be mimicked by the non-selective 5-HT receptor agonist 5-methoxytryptamine. All tested agonists that display at least some receptor subtype specificity in mammals, i.e., 5-carboxamidotryptamine, (+/-)-8-OH-DPAT, (+/-)-DOI, and AS 19, were ineffective in stimulating salivary secretion. 5-HT-induced secretion can be blocked by the vertebrate 5-HT receptor antagonists methiothepin, cyproheptadine, and mianserin. Our pharmacological data indicate that the pharmacology of arthropod 5-HT receptors is remarkably different from that of their vertebrate counterparts. (C) 2007 Elsevier Ltd. All rights reserved. KW - Biogenic amine KW - G protein-coupled receptor KW - insect KW - salivary gland KW - secretion Y1 - 2007 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus-44319 ER - TY - GEN A1 - Blenau, Wolfgang A1 - Rotte, Cathleen A1 - Krach, Christian A1 - Balfanz, Sabine A1 - Baumann, Arnd A1 - Walz, Bernd T1 - Molecular characterization and localization of the first tyramine receptor of the American cockroach (Periplaneta americana) N2 - The phenolamines octopamine and tyramine control, regulate, and modulate many physiological and behavioral processes in invertebrates. Vertebrates possess only small amounts of both substances, and thus, octopamine and tyramine, together with other biogenic amines, are referred to as “trace amines.” Biogenic amines evoke cellular responses by activating G-protein-coupled receptors. We have isolated a complementary DNA (cDNA) that encodes a biogenic amine receptor from the American cockroach Periplaneta americana, viz., Peatyr1, which shares high sequence similarity to members of the invertebrate tyramine-receptor family. The PeaTYR1 receptor was stably expressed in human embryonic kidney (HEK) 293 cells, and its ligand response has been examined. Receptor activation with tyramine reduces adenylyl cyclase activity in a dose-dependent manner (EC50 350 nM). The inhibitory effect of tyramine is abolished by co-incubation with either yohimbine or chlorpromazine. Receptor expression has been investigated by reverse transcription polymerase chain reaction and immunocytochemistry. The mRNA is present in various tissues including brain, salivary glands, midgut, Malpighian tubules, and leg muscles. The effect of tyramine on salivary gland acinar cells has been investigated by intracellular recordings, which have revealed excitatory presynaptic actions of tyramine. This study marks the first comprehensive molecular, pharmacological, and functional characterization of a tyramine receptor in the cockroach. KW - Biogenic amine KW - cellular signaling KW - G-protein-coupled receptor KW - octopamine KW - salivary gland Y1 - 2009 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus-44335 ER - TY - GEN A1 - Blenau, Wolfgang A1 - Mustard, Julie A. A1 - Hamilton, Ingrid S. A1 - Ward, Vernon K. A1 - Ebert, Paul R. A1 - Mercer, Alison R. T1 - Analysis of two D1-like dopamine receptors from the honey bee Apis mellifera reveals agonist-independent activity N2 - Dopamine is found in many invertebrate organisms, including insects, however, the mechanisms through which this amine operates remain unclear. We have expressed two dopamine receptors cloned from honey bee (AmDOP1 and AmDOP2) in insect cells (Spodoptera frugiperda), and compared their pharmacology directly using production of cAMP as a functional assay. In each assay, AmDOP1 receptors required lower concentrations of dopamine and 6,7-ADTN for maximal activation than AmDOP2 receptors. Conversely, butaclamol and cis(Z)-flupentixol were more potent at blocking the cAMP response mediated through AmDOP2 than AmDOP1 receptors. Expression of AmDOP1, but not AmDOP2, receptors significantly increased levels of cAMP even in the absence of ligand. This constitutive activity was blocked by cis(Z)-flupentixol. This work provides the first evidence of a constitutively activated dopamine receptor in invertebrates and suggests that although AmDOP1 and AmDOP2 share much less homology than their vertebrate counterparts, they display a number of functional parallels with the mammalian D1-like dopamine receptors. T3 - Zweitveröffentlichungen der Universität Potsdam : Mathematisch-Naturwissenschaftliche Reihe - paper 109 KW - G protein-coupled receptor KW - Biogenic amine KW - Invertebrate KW - cAMP KW - Baculovirus Y1 - 2003 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus-44378 ER - TY - GEN A1 - Blenau, Wolfgang A1 - Grohmann, Lore A1 - Erber, Joachim A1 - Ebert, Paul R. A1 - Strünker, Timo A1 - Baumann, Arnd T1 - Molecular and functional characterization of an octopamine receptor from honeybee (Apis mellifera) brain N2 - Biogenic amines and their receptors regulate and modulate many physiological and behavioural processes in animals. In vertebrates, octopamine is only found in trace amounts and its function as a true neurotransmitter is unclear. In protostomes, however, octopamine can act as neurotransmitter, neuromodulator and neurohormone. In the honeybee, octopamine acts as a neuromodulator and is involved in learning and memory formation. The identification of potential octopamine receptors is decisive for an understanding of the cellular pathways involved in mediating the effects of octopamine. Here we report the cloning and functional characterization of the first octopamine receptor from the honeybee, Apis mellifera . The gene was isolated from a brain-specific cDNA library. It encodes a protein most closely related to octopamine receptors from Drosophila melanogaster and Lymnea stagnalis . Signalling properties of the cloned receptor were studied in transiently transfected human embryonic kidney (HEK) 293 cells. Nanomolar to micromolar concentrations of octopamine induced oscillatory increases in the intracellular Ca2+ concentration. In contrast to octopamine, tyramine only elicited Ca2+ responses at micromolar concentrations. The gene is abundantly expressed in many somata of the honeybee brain, suggesting that this octopamine receptor is involved in the processing of sensory inputs, antennal motor outputs and higher-order brain functions. KW - Biogenic amine KW - Ca2+ KW - cyclic AMP KW - G protein-coupled receptor KW - insect Y1 - 2003 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus-44293 ER -