title: 5-HT1A receptor-mediated G protein activation assessed by [35S]GTPgammaS binding in rat cerebral cortex.
abstract: To date, 5-hydroxytryptamine1A (5-HT1A) receptor-mediated functional assays (adenylyl cyclase inhibition, high-affinity GTPase activity and [35S]guanosine-5'-O-(gamma-thio)-triphosphate ([35S]GTPgammaS) binding) have been performed mainly in hippocampal membranes. In the current study, 5-HT-stimulated G protein activation assays were carried out in rat cerebral cortical membranes. High-affinity GTPase activity was stimulated by 5-HT, but not by 8-hydroxy-2-(di-n-propylamino)tetralin (8-OH-DPAT). By contrast, 5-HT- and 8-OH-DPAT-stimulated [35S]GTPgammaS binding displayed sufficient dynamic range enough to warrant further pharmacological analysis. Under standard conditions, which were determined precisely in terms of the concentrations of GDP, MgCl2 and NaCl, the profile of 5-HT-stimulated [35S]GTPgammaS binding investigated using a series of 5-HT receptor agonists and antagonists clearly indicated the involvement of the 5-HT1A receptor subtype. There appeared to be no evidence supporting the presence of regional heterogeneity in coupling efficiency between 5-HT1A and G proteins in the hippocampus or cortex. This method is a useful tool for investigating functional coupling between postsynaptic 5-HT1A receptors and G proteins in cerebral cortical membranes.
authors.affiliation: Department of Psychiatry, Saitama Medical School, 38 Morohongo, Moroyama-machi, Iruma-gun, Staitama 350-0495, Japan. odagaki@saitama-med.ac.jp
authors.forename: Yuji
authors.initials: Y
authors.lastname: Odagaki
authors.forename: Ryoichi
authors.initials: R
authors.lastname: Toyoshima
mesh_terms: D017371:8-Hydroxy-2-(di-n-propylamino)tetralin / Q000494:pharmacology; D000818:Animals; D001667:Binding, Competitive / Q000187:drug effects; D002462:Cell Membrane / Q000187:drug effects / Q000378:metabolism; D002540:Cerebral Cortex / Q000187:drug effects / Q000201:enzymology / Q000378:metabolism*; D004305:Dose-Response Relationship, Drug; D004789:Enzyme Activation / Q000187:drug effects; D020558:GTP Phosphohydrolases / Q000378:metabolism; D019204:GTP-Binding Proteins / Q000378:metabolism*; D016244:Guanosine 5'-O-(3-Thiotriphosphate) / Q000378:metabolism*; D006153:Guanosine Diphosphate / Q000494:pharmacology; D006624:Hippocampus / Q000187:drug effects / Q000378:metabolism; D015636:Magnesium Chloride / Q000494:pharmacology; D008297:Male; D010879:Piperazines / Q000494:pharmacology; D011725:Pyridines / Q000494:pharmacology; D011810:Quinoxalines / Q000494:pharmacology; D051381:Rats; D017207:Rats, Sprague-Dawley; D044282:Receptor, Serotonin, 5-HT1A / Q000502:physiology*; D012701:Serotonin / Q000494:pharmacology; D058825:Serotonin 5-HT1 Receptor Agonists; D058829:Serotonin 5-HT1 Receptor Antagonists; D012702:Serotonin Antagonists / Q000494:pharmacology; D017366:Serotonin Receptor Agonists / Q000494:pharmacology; D012965:Sodium Chloride / Q000494:pharmacology; D013462:Sulfur Radioisotopes
chemical_list: D010879:Piperazines; D011725:Pyridines; D011810:Quinoxalines; D058825:Serotonin 5-HT1 Receptor Agonists; D058829:Serotonin 5-HT1 Receptor Antagonists; D012702:Serotonin Antagonists; D017366:Serotonin Receptor Agonists; D013462:Sulfur Radioisotopes; D015636:Magnesium Chloride; C052561:CGS 12066B; D044282:Receptor, Serotonin, 5-HT1A; D006153:Guanosine Diphosphate; D012701:Serotonin; D016244:Guanosine 5'-O-(3-Thiotriphosphate); D012965:Sodium Chloride; C090413:N-(2-(4-(2-methoxyphenyl)-1-piperazinyl)ethyl)-N-(2-pyridinyl)cyclohexanecarboxamide; D017371:8-Hydroxy-2-(di-n-propylamino)tetralin; D020558:GTP Phosphohydrolases; D019204:GTP-Binding Proteins