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J Neurosci ; 24(13): 3421-35, 2004 Mar 31.
Artigo em Inglês | MEDLINE | ID: mdl-15056722


The stomatogastric nervous system (STNS) is a premiere model for studying modulation of motor pattern generation. Whereas the cellular and network responses to monoamines have been particularly well characterized electrophysiologically, the transduction mechanisms that link the different monoaminergic signals to specific intracellular responses are presently unknown in this system. To begin to elucidate monoaminergic signal transduction in pyloric neurons, we used a bioinformatics approach to predict the existence of 18 monoamine receptors in arthropods, 9 of which have been previously cloned in Drosophila and other insects. We then went on to use the two existing insect databases to clone and characterize the 10th putative arthropod receptor from the spiny lobster, Panulirus interruptus. This receptor is most homologous to the 5-HT2 subtype and shows a dose-dependent response to 5-HT but not to any of the other monoamines present in the STNS. Through a series of pharmacological experiments, we demonstrate that this newly described receptor, 5-HT2betaPan, couples with the traditional G(q) pathway when expressed in HEK293 cells, but not to G(s) or G(i/o). Moreover, it is constitutively active, because the highly conserved DRY motif in transmembrane region 3 has evolved into DRF. Site-directed mutagenesis that reverts the motif back to DRY abolishes this agonist-independent activity. We further demonstrate that this receptor most likely participates in the modulation of stomatogastric motor output, because it is found in neurites in the synaptic neuropil of the stomatogastric ganglion as well as in the axon terminals at identified pyloric neuromuscular junctions.

Neurotransmissores/metabolismo , Palinuridae/fisiologia , Receptores de Neurotransmissores/metabolismo , Receptores 5-HT2 de Serotonina/genética , Receptores 5-HT2 de Serotonina/metabolismo , Motivos de Aminoácidos/fisiologia , Sequência de Aminoácidos , Animais , Aminas Biogênicas/farmacologia , Aminas Biogênicas/fisiologia , Linhagem Celular , Clonagem Molecular , Biologia Computacional/métodos , Sequência Conservada/fisiologia , Sistema Digestório/inervação , Drosophila/genética , Evolução Molecular , Subunidades alfa Gq-G11 de Proteínas de Ligação ao GTP/metabolismo , Humanos , Dados de Sequência Molecular , Mutagênese Sítio-Dirigida , Rede Nervosa/metabolismo , Rede Nervosa/fisiologia , Palinuridae/genética , Proteína Quinase C/metabolismo , Receptores de Neurotransmissores/agonistas , Homologia de Sequência de Aminoácidos , Transdução de Sinais/efeitos dos fármacos , Transdução de Sinais/fisiologia , Relação Estrutura-Atividade , Fosfolipases Tipo C/metabolismo