Tags

Type your tag names separated by a space and hit enter

Native rat hippocampal 5-HT1A receptors show constitutive activity.
Mol Pharmacol. 2007 Mar; 71(3):638-43.MP

Abstract

Previous studies have shown that human 5-hydroxytryptamine (5-HT)1A receptors stably expressed in transfected cell lines show constitutive G-protein activity, as revealed by the inhibitory effect of inverse agonists, such as spiperone, on basal guanosine-5'-O-(3-[35S]thio)-triphosphate ([35S]GTPgammaS) binding. In the present study, we evaluated the constitutive activity of native rat 5-HT1A receptors in hippocampal membranes. Using anti-Galphao-antibody capture coupled to scintillation proximity assay under low sodium (30 mM) conditions, we observed high basal [35S]GTPgammaS binding to Galphao subunits (defined as 100%). Under these conditions, 5-HT and the prototypic selective 5-HT1A agonist (+)8-hydroxy-2-(di-n-propylamino)tetralin [(+)-8-OH-DPAT] both stimulated [35S]GTPgammaS binding to Galphao to a similar extent, raising binding to approximately 130% of basal with pEC50 values of 7.91 and 7.87, respectively. The 5-HT1A-selective neutral antagonist [O-methyl-3H]-N-(2-(4-(2-methoxyphenyl)-1-piperazinyl)ethyl)-N-(2-pyridinyl)cyclohexanecarboxamide trihydrochloride (WAY100,635) could block these effects in a competitive manner with pKb values (5-HT, 9.57; (+)-8-OH-DPAT, 9.52) that are consistent with its pKi value at r5-HT1A receptors (9.33). In this native receptor system, spiperone and methiothepin reduced basal [35S]GTPgammaS binding to Galphao in a concentration-dependent manner to 90% of basal with pIC50 values of 7.37 and 7.98, respectively. The inhibition of basal [35S]GTPgammaS binding induced by maximally effective concentrations of spiperone (10 microM) or methiothepin (1 microM) was antagonized by WAY100,635 in a concentration-dependent manner (pKb, 9.52 and 8.87, respectively), thus indicating that this inverse agonism was mediated by 5-HT1A receptors. These data provide the first demonstration that native rat serotonin 5-HT1A receptors can exhibit constitutive activity in vitro.

Authors+Show Affiliations

Department of Neurobiology 2, Institut de Recherche Pierre Fabre, France. jean.claude.martel@pierre-fabre.comNo affiliation info availableNo affiliation info availableNo affiliation info availableNo affiliation info availableNo affiliation info available

Pub Type(s)

Journal Article

Language

eng

PubMed ID

17167032

Citation

Martel, Jean-Claude, et al. "Native Rat Hippocampal 5-HT1A Receptors Show Constitutive Activity." Molecular Pharmacology, vol. 71, no. 3, 2007, pp. 638-43.
Martel JC, Ormière AM, Leduc N, et al. Native rat hippocampal 5-HT1A receptors show constitutive activity. Mol Pharmacol. 2007;71(3):638-43.
Martel, J. C., Ormière, A. M., Leduc, N., Assié, M. B., Cussac, D., & Newman-Tancredi, A. (2007). Native rat hippocampal 5-HT1A receptors show constitutive activity. Molecular Pharmacology, 71(3), 638-43.
Martel JC, et al. Native Rat Hippocampal 5-HT1A Receptors Show Constitutive Activity. Mol Pharmacol. 2007;71(3):638-43. PubMed PMID: 17167032.
* Article titles in AMA citation format should be in sentence-case
TY - JOUR T1 - Native rat hippocampal 5-HT1A receptors show constitutive activity. AU - Martel,Jean-Claude, AU - Ormière,Anne-Marie, AU - Leduc,Nathalie, AU - Assié,Marie-Bernadette, AU - Cussac,Didier, AU - Newman-Tancredi,Adrian, Y1 - 2006/12/13/ PY - 2006/12/15/pubmed PY - 2007/3/23/medline PY - 2006/12/15/entrez SP - 638 EP - 43 JF - Molecular pharmacology JO - Mol. Pharmacol. VL - 71 IS - 3 N2 - Previous studies have shown that human 5-hydroxytryptamine (5-HT)1A receptors stably expressed in transfected cell lines show constitutive G-protein activity, as revealed by the inhibitory effect of inverse agonists, such as spiperone, on basal guanosine-5'-O-(3-[35S]thio)-triphosphate ([35S]GTPgammaS) binding. In the present study, we evaluated the constitutive activity of native rat 5-HT1A receptors in hippocampal membranes. Using anti-Galphao-antibody capture coupled to scintillation proximity assay under low sodium (30 mM) conditions, we observed high basal [35S]GTPgammaS binding to Galphao subunits (defined as 100%). Under these conditions, 5-HT and the prototypic selective 5-HT1A agonist (+)8-hydroxy-2-(di-n-propylamino)tetralin [(+)-8-OH-DPAT] both stimulated [35S]GTPgammaS binding to Galphao to a similar extent, raising binding to approximately 130% of basal with pEC50 values of 7.91 and 7.87, respectively. The 5-HT1A-selective neutral antagonist [O-methyl-3H]-N-(2-(4-(2-methoxyphenyl)-1-piperazinyl)ethyl)-N-(2-pyridinyl)cyclohexanecarboxamide trihydrochloride (WAY100,635) could block these effects in a competitive manner with pKb values (5-HT, 9.57; (+)-8-OH-DPAT, 9.52) that are consistent with its pKi value at r5-HT1A receptors (9.33). In this native receptor system, spiperone and methiothepin reduced basal [35S]GTPgammaS binding to Galphao in a concentration-dependent manner to 90% of basal with pIC50 values of 7.37 and 7.98, respectively. The inhibition of basal [35S]GTPgammaS binding induced by maximally effective concentrations of spiperone (10 microM) or methiothepin (1 microM) was antagonized by WAY100,635 in a concentration-dependent manner (pKb, 9.52 and 8.87, respectively), thus indicating that this inverse agonism was mediated by 5-HT1A receptors. These data provide the first demonstration that native rat serotonin 5-HT1A receptors can exhibit constitutive activity in vitro. SN - 0026-895X UR - https://www.unboundmedicine.com/medline/citation/17167032/Native_rat_hippocampal_5_HT1A_receptors_show_constitutive_activity_ L2 - http://molpharm.aspetjournals.org/cgi/pmidlookup?view=long&pmid=17167032 DB - PRIME DP - Unbound Medicine ER -