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 - 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 -