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  - Schlenstedt, Jana
A1  - Balfanz, Sabine
A1  - Baumann, Arnd
A1  - Blenau, Wolfgang
T1  - Am5-HT7 : molecular and pharmacological characterization of the first serotonin receptor of the honeybee (Apis mellifera)
N2  - The biogenic amine serotonin (5-HT) plays a key role in the regulation and modulation of many physiological and behavioural processes in both vertebrates and invertebrates. These functions are mediated through the binding of serotonin to its receptors, of which 13 subtypes have been characterized in vertebrates. We have isolated a cDNA from the honeybee Apis mellifera (Am5-ht7) sharing high similarity to members of the 5-HT7 receptor family. Expression of the Am5-HT7 receptor in HEK293 cells results in an increase in basal cAMP levels, suggesting that Am5-HT7 is expressed as a constitutively active receptor. Serotonin application to Am5-ht7-transfected cells elevates cyclic adenosine 3',5'-monophosphate (cAMP) levels in a dose-dependent manner (EC50 = 1.1-1.8 nM). The Am5-HT7 receptor is also activated by 5-carboxamidotryptamine, whereas methiothepin acts as an inverse agonist. Receptor expression has been investigated by RT-PCR, in situ hybridization, and western blotting experiments. Receptor mRNA is expressed in the perikarya of various brain neuropils, including intrinsic mushroom body neurons, and in peripheral organs. This study marks the first comprehensive characterization of a serotonin receptor in the honeybee and should facilitate further analysis of the role(s) of the receptor in mediating the various central and peripheral effects of 5-HT.
KW  - Behaviour
KW  - biogenic amine
KW  - cellular signalling
KW  - constitutive activity
KW  - cyclic AMP
Y1  - 2006
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus-44423
ER  -