G-protein activation at 5-HT1A receptors by the 5-ht1F ligand LY334370 in guinea-pig brain sections and recombinant cell lines.
1. G-protein activation by the 5-ht1F receptor agonist 5-(4-fluorobenzoyl)amino-3-(1-methylpiperidin-4-yl)-1H-indole fumarate (LY334370) was investigated by use of autoradiography of receptor-activated G-proteins in guinea-pig brain sections and [35S]-GTPgammaS binding responses in cell lines stably expressing human 5-HT1A (h 5-HT1A) receptors. 2. LY334370 (10 microM) caused little or no stimulation of [35S]-GTPgammaS binding in guinea-pig brain regions enriched in 5-ht1F binding sites (e.g., claustrum, caudate/putamen and thalamic nuclei), as identified by labelling with 10 nM [3H]-sumatriptan plus 10 nM 5-carboxamidotryptamine (5-CT). 3. Application of LY334370 (10 microM) to guinea-pig brain sections resulted in an increase of [35S]-GTPgammaS binding in hippocampus (123+/-17%), lateral septum (58+/-14%), dorsal raphe (57+/-10%), entorhinal (37+/-11%) and cingulate cortex (28+/-10%). This distribution fits with the G-protein activation mediated by 5-HT1A receptors as found with lisuride (10 microM), and labelling of 5-HT1A receptors by 140 pM [125I]-4-(2'-methoxy-phenyl)- -[2'-(n-2"-pyridinyl)-p-iodobenzamido]-ethyl-piperazine (p-MPPI). 4. The LY334370-mediated [35S]-GTPgammaS response was antagonized by the selective, silent 5-HT1A receptor antagonist N-[2-[4-(2-methoxyphenyl)1-piperazinyl]ethyl]-N-(2-pyridinyl)cyclohex anecarboxa-mide (WAY100635, 1 microM) in each of the brain structures investigated. The distribution pattern of the [35S]-GTPgammaS binding response and the antagonist profile suggest that the LY334370-induced response in guinea-pig brain is mediated by 5-HT1A receptors. 5. The maximal LY334370-induced [35S]-GTPgammaS binding response (83 to 94%) in membranes of recombinant C6-glial/h 5-HT1A and HeLa/h 5-HT1A cells was close to that of 5-HT, suggesting LY334370 to exert high intrinsic activity at h 5-HT1A receptors. 6. In conclusion, in guinea-pig brain sections and recombinant cell lines the 5-ht1F receptor agonist LY334370 causes G-protein activation that is mediated by 5-HT1A receptors. Caution should be taken when employing this ligand as a putative selective 5-ht1F agonist.
Dupuis
D S
DS
Department of Cellular and Molecular Biology, Centre de Recherche Pierre Fabre, Castres, France.
Colpaert
F C
FC
Pauwels
P J
PJ
D000631:Aminopyridines / Q000378:metabolism; D000818:Animals; D001345:Autoradiography; D001549:Benzamides / Q000494:pharmacology*; D001665:Binding Sites; D001667:Binding, Competitive; D001921:Brain / Q000187:drug effects* / Q000378:metabolism; D019204:GTP-Binding Proteins / Q000378:metabolism*; D016244:Guanosine 5'-O-(3-Thiotriphosphate) / Q000378:metabolism; D006168:Guinea Pigs; D006367:HeLa Cells; D006624:Hippocampus / Q000378:metabolism; D006801:Humans; D007211:Indoles / Q000494:pharmacology*; D008297:Male; D010879:Piperazines / Q000378:metabolism / Q000494:pharmacology; D011725:Pyridines / Q000494:pharmacology; D011903:Raphe Nuclei / Q000187:drug effects / Q000378:metabolism; D011985:Receptors, Serotonin / Q000187:drug effects* / Q000378:metabolism; D044263:Receptors, Serotonin, 5-HT1; D012701:Serotonin / Q000031:analogs & derivatives / Q000378:metabolism; D012702:Serotonin Antagonists / Q000378:metabolism / Q000494:pharmacology*; D017366:Serotonin Receptor Agonists / Q000494:pharmacology*; D018170:Sumatriptan / Q000378:metabolism
C108218:4-fluoro-N-(3-(1-methyl-4-piperidinyl)-1H-indol-5-yl)benzamide; D000631:Aminopyridines; D001549:Benzamides; D007211:Indoles; D010879:Piperazines; D011725:Pyridines; D011985:Receptors, Serotonin; D044263:Receptors, Serotonin, 5-HT1; D012702:Serotonin Antagonists; D017366:Serotonin Receptor Agonists; C087205:4-(2'-methoxyphenyl)-1-(2'-(N-(2''-pyridinyl)-4-iodobenzamido)ethyl)piperazine; D012701:Serotonin; D016244:Guanosine 5'-O-(3-Thiotriphosphate); C090413:N-(2-(4-(2-methoxyphenyl)-1-piperazinyl)ethyl)-N-(2-pyridinyl)cyclohexanecarboxamide; D018170:Sumatriptan; C047087:5-carboxamidotryptamine; D019204:GTP-Binding Proteins