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Baamonde A, Lastra A, Villazón M, Bordallo J, Hidalgo A, Menéndez L. Involvement of endogenous endothelins in thermal and mechanical inflammatory hyperalgesia in mice. Naunyn Schmiedebergs Arch Pharmacol 2003; 369:245-51. [PMID: 14661069 DOI: 10.1007/s00210-003-0841-1] [Citation(s) in RCA: 47] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2003] [Accepted: 10/07/2003] [Indexed: 10/26/2022]
Abstract
Endothelin receptors have been involved in inflammatory, neuropathic and tumoral pain. In the case of inflammatory hyperalgesia, some previous papers have pointed towards the involvement of ETB receptors, although the stimulation of ETA receptors seems to participate in the development of the inflammatory reaction. We have studied the effect of ETA and ETB receptor antagonists in the thermal and mechanical hyperalgesia induced in a model of acute (induced by carrageenan) and chronic (induced by complete Freund's adjuvant, CFA) inflammation in mice. The i.pl. administration of the selective ETA antagonist BQ-123 (1-10 nmol) antagonized the thermal hyperalgesia detected by the unilateral hot plate test, observed in both inflammatory models, whereas the i.pl. administration of the ETB selective antagonist BQ-788 (17.7 nmol) failed to modify this. In contrast, both BQ-123 (3-17.7 nmol) and BQ-788 (3-17.7 nmol) antagonized the mechanical hyperalgesia, as assessed by the Randall-Selitto test in carrageenan- and CFA-treated mice. Both BQ-123 and BQ-788 were able to antagonize the mechanical hyperalgesia induced by ET-1 (200 pmol; i.pl.) in the same dose range. Thus, ETA receptors are involved in both thermal and mechanical hyperalgesia whereas ETB receptors are only involved in mechanical hyperalgesia in these inflammatory models. In conclusion, the role of ETB receptors in inflammatory pain is further supported and new insights into the participation of ETA receptors in inflammatory hyperalgesia are given.
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Affiliation(s)
- Ana Baamonde
- Laboratorio de Farmacología, Facultad de Medicina, Universidad de Oviedo, C/ Julián Clavería 6, 33006 Oviedo, Asturias, Spain.
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2
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Villazón M, Enguix MJ, Tristán H, Honrubia MA, Brea J, Maayani S, Cadavid MI, Loza MI. Different pharmacological properties of two equipotent antagonists (clozapine and rauwolscine) for 5-HT2B receptors in rat stomach fundus. Biochem Pharmacol 2003; 66:927-37. [PMID: 12963479 DOI: 10.1016/s0006-2952(03)00426-x] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/01/2022]
Abstract
On the basis of the previously demonstrated constitutive activity in natural systems and the possibility of specific ligand-induced conformations, the aims of this study were: (i) to characterize the effects of two competitive antagonists (rauwolscine, RAU and clozapine, CLO) with very similar potencies for 5-HT(2B) receptors in a natural system (rat stomach fundus), and (ii) to evaluate a new method for detecting ligand-specific generated conformations through the study of the effects of RAU and CLO in 5-HT efficacy and in the time course of the response to the agonists. RAU and CLO behaved as competitive antagonists and showed similar potencies (pA(2) 7.56+/-0.25 and 7.50+/-0.30, respectively). However, RAU displayed greater efficacy than CLO in relaxing basal tension (10 microM CLO represented 64+/-6% of 10 microM RAU-induced relaxation). CLO partially reverted RAU-induced relaxation and RAU promoted an additional relaxation of maximal CLO-induced relaxation. This may indicate different degrees of inverse agonism. RAU also was more effective in generating insurmountable antagonism after long-term incubation (>3 hr) and modified the time course of the 5-HT(2B) response to 5-HT; conversely, CLO did not affect the time course of this response. This suggests that classical competitive antagonists may generate different specific conformational states and differential effects on receptor system regulation.
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Affiliation(s)
- María Villazón
- Departamento de Farmacología, Facultad de Farmacia, Universidad de Santiago de Compostela, Avenida de las Ciencias s/n, Campus Sur, 15782 Santiago de Compostela, A Coruña, Spain
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3
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Enguix MJ, Sánchez L, Villazón M, Brea J, Tristán H, Caruncho HJ, Cadavid MI, Loza MI. Differential regulation of rat peripheral 5-HT(2A) and 5-HT(2B) receptor systems: influence of drug treatment. Naunyn Schmiedebergs Arch Pharmacol 2003; 368:79-90. [PMID: 12861437 DOI: 10.1007/s00210-003-0775-7] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/01/2002] [Accepted: 05/08/2003] [Indexed: 10/26/2022]
Abstract
Most studies of 5-HT(2) receptor regulation have been carried out on the central nervous system (CNS) (which expresses 5-HT(2A) and 5-HT(2C) receptors); very few in vitro studies have addressed the peripheral receptors 5-HT(2A) and 5-HT(2B). The aim of this investigation was to compare the possible short- and long-term processes regulating these peripheral receptors in the rat. The in vitro contractile response elicited by serotonin (5-HT, 10 micro M) in the rat gastric fundus (5-HT(2B) receptor system) was rapid and followed by a partial fade to a steady state, in contrast with the rat thoracic aorta response (5-HT(2A) receptor system), which was more stable, slower and sustained. To characterize drug-receptor interactions, cumulative concentration/response curves (CCRCs) for 5-HT were constructed ex vivo for rat tissues treated with drugs acting at these receptors. Rats were examined 4 or 24 h after a single, i.p. administration of (+/-)1-(2,5-dimethoxy-4-iodophenyl)-2-aminopropane [(+/-)DOI, 1 or 2.5 mg/kg], clozapine, cyproheptadine or rauwolscine (10 mg/kg), 48 h after a single i.p. administration of (+/-)DOI (2.5 mg/kg), clozapine or cyproheptadine (10 mg/kg) or 24 h after the last of with 15 daily i.p. administrations of (+/-)DOI (1 or 2.5 mg/kg), clozapine, cyproheptadine or rauwolscine (10 mg/kg). In the aorta, E(max) (the maximum response elicited by 5-HT) was unchanged 4 h after a single dose of any of the drugs tested. However, 24 h after a single dose, E(max) was lower in animals treated with (+/-)DOI (2.5 mg/kg), clozapine or cyproheptadine than in controls, whilst 48 h after a single dose of (+/-)DOI (2.5 mg/kg), clozapine or cyproheptadine there was no difference in E(max) between experimental and control animals. After chronic treatment with (+/-)DOI (2.5 mg/kg), clozapine and cyproheptadine, E(max) was lower than in controls. In the gastric fundus, E(max) 4 h after a single dose of each drug was lower than in controls, and the response recovered by 24 or 48 h. Following chronic treatment, E(max) was significantly lower than in controls for each drug used. These findings suggest first, that regulation of peripheral 5-HT(2) receptors (5-HT(2A) and 5-HT(2B)) is a functionally significant phenomenon in vivo, and occurs after administration of both agonists and antagonists. Second, the kinetics of peripheral 5-HT(2) receptor regulation were similar in both in vivo and ex vivo experiments. The 5-HT(2B) receptors in rat gastric fundus are more sensitive to drug-induced regulation than the 5-HT(2A) rat aortic receptors. Finally, long-term regulation of both receptors stabilizes short-term desensitization for longer.
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MESH Headings
- Amphetamines/pharmacology
- Animals
- Antipsychotic Agents/pharmacology
- Aorta, Thoracic/drug effects
- Aorta, Thoracic/metabolism
- Aorta, Thoracic/physiology
- Clozapine/pharmacology
- Cyproheptadine/pharmacology
- Gastric Fundus/drug effects
- Gastric Fundus/metabolism
- Gastric Fundus/physiology
- In Vitro Techniques
- Ligands
- Male
- Muscle Contraction/drug effects
- Muscle, Smooth/drug effects
- Muscle, Smooth/metabolism
- Muscle, Smooth/physiology
- Muscle, Smooth, Vascular/drug effects
- Muscle, Smooth, Vascular/metabolism
- Muscle, Smooth, Vascular/physiology
- Rats
- Rats, Sprague-Dawley
- Receptor, Serotonin, 5-HT2A/drug effects
- Receptor, Serotonin, 5-HT2A/metabolism
- Receptor, Serotonin, 5-HT2B/drug effects
- Receptor, Serotonin, 5-HT2B/metabolism
- Serotonin/metabolism
- Serotonin Antagonists/pharmacology
- Serotonin Receptor Agonists/pharmacology
- Yohimbine/pharmacology
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Affiliation(s)
- M J Enguix
- School of Pharmacy, University of Santiago de Compostela, 15782, Santiago de Compostela, Spain
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4
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Brea J, Masaguer CF, Villazón M, Cadavid MI, Raviña E, Fontaine F, Dezi C, Pastor M, Sanz F, Loza MI. Conformationally constrained butyrophenones as new pharmacological tools to study 5-HT 2A and 5-HT 2C receptor behaviours. Eur J Med Chem 2003; 38:433-40. [PMID: 12750032 DOI: 10.1016/s0223-5234(03)00054-0] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
This study presents new pharmacological and molecular modelling studies on a recently described series of conformationally constrained butyrophenones. Alignment-free three-dimensional quantitative structure-activity relationship models developed on the basis of GRid Independent descriptors and partial least squares regression analysis, allow feasible predictions of activity of new compounds and reveal structural requirements for optimal affinity, particularly in the case of the 5-HT(2A) receptor. The requirements for the 5-HT(2A) affinity consist in a precise distance between hydrogen bond donor (protonated amino group) and hydrogen bond acceptor groups, as well as an optimal distance between the protonated amino group and the farthest extreme of the compounds. Another significant result has been the characterisation of two structurally similar compounds as interesting pharmacological tools (1-[(4-Oxo-4,5,6,7-tetrahydrobenzo[b]furan-5-yl)ethyl]-4-(6-fluorobenzisoxazol-3-yl)piperidine and 1-[(4-Oxo-4,5,6,7-tetrahydrobenzo[b]furan-6-yl)methyl]-4-(6-fluorobenzisoxazol-3-yl)piperidine). In spite of their structural similarity, the first compound shows clearly higher affinity for the 5-HT(2C) receptor (about 100 fold) and higher Meltzer ratio (1.17 vs. 0.99) than the second. Moreover, the first compound inhibits arachidonic acid release in a biphasic concentration-dependent way in functional experiments at the 5-HT(2A) receptor and it acts as inverse agonist at the 5-HT(2C) receptor, behaviours that are not shown by the second compound.
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MESH Headings
- Animals
- Arachidonic Acid/metabolism
- Binding, Competitive/drug effects
- Butyrophenones/chemical synthesis
- Butyrophenones/chemistry
- Butyrophenones/pharmacology
- CHO Cells
- Cattle
- Cricetinae
- Dose-Response Relationship, Drug
- Humans
- Inositol Phosphates/metabolism
- Models, Molecular
- Molecular Conformation
- Molecular Structure
- Rats
- Receptor, Serotonin, 5-HT2A/drug effects
- Receptor, Serotonin, 5-HT2A/metabolism
- Receptor, Serotonin, 5-HT2C/drug effects
- Receptor, Serotonin, 5-HT2C/metabolism
- Receptors, Serotonin/drug effects
- Receptors, Serotonin/metabolism
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Affiliation(s)
- José Brea
- Facultad de Farmacia, Departamentos de Farmacologi;a, Universidad de Santiago de Compostela, 15782, Santiago de Compostela, Spain
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5
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González-Gómez JC, Santana L, Uriarte E, Brea J, Villazón M, Loza MI, De Luca M, Rivas ME, Montenegro GY, Fontenla JA. New arylpiperazine derivatives with high affinity for alpha1A, D2 and 5-HT2A receptors. Bioorg Med Chem Lett 2003; 13:175-8. [PMID: 12482418 DOI: 10.1016/s0960-894x(02)00933-2] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
Abstract
A series of novel long-chain arylpiperazines bearing a coumarin fragment was synthesized and the compounds were evaluated for their affinity at alpha(1), D(2 )and 5-HT(2A) receptors. Most of the new compounds showed high affinity for the three types of receptors alpha(1A), D(2) and 5-HT(2A) which depends, fundamentally, on the substitution of the N(4) of the piperazine ring. From the series emerged compound 6, which had an haloperidol-like profile at D(2) and 5HT(2A) receptors (pK(i) values of 7.93 and 6.76 respectively). The higher alpha(1A) receptor affinity (pA(2)=9.07) of this compound could contribute to a more atypical antipsychotic profile than the haloperidol.
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MESH Headings
- Algorithms
- Animals
- Aorta, Thoracic/drug effects
- Coumarins/chemistry
- Dopamine Antagonists/pharmacology
- Haloperidol/pharmacology
- In Vitro Techniques
- Indicators and Reagents
- Male
- Muscle, Smooth, Vascular/drug effects
- Piperazines/chemical synthesis
- Piperazines/pharmacology
- Rats
- Rats, Sprague-Dawley
- Receptor, Serotonin, 5-HT2A
- Receptors, Adrenergic, alpha-1/drug effects
- Receptors, Dopamine D2/drug effects
- Receptors, Serotonin/drug effects
- Structure-Activity Relationship
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Affiliation(s)
- J C González-Gómez
- Department of Organic Chemistry, Faculty of Pharmacy, University of Santiago, Campus Sur s/n, E-15782 Santiago de Compostela, Spain.
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6
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Villazón M, Padín JF, Cadavid MI, Enguix MJ, Tristán H, Orallo F, Loza MI. Functional characterization of serotonin receptors in rat isolated aorta. Biol Pharm Bull 2002; 25:584-90. [PMID: 12033497 DOI: 10.1248/bpb.25.584] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Interactions of serotonin (5-HT) with different specific 5-HT receptors that can coexist in the same blood vessel sometimes generate opposite effects. The aim of this study was to characterize the functional role of previously described mRNAs for 5-HT receptors in the rat aorta (5-HT(2A), 5-HT(2B), 5-HT(1B), 5-HT(7)) as well as to study the known 5-HT(2A) receptor-mediated constrictor response and investigate the influences of endothelium and preconstriction on the tissue in that response. A slight endothelium- and concentration-dependent relaxant effect was observed for 5-HT in aorta precontracted with either 5 microM phenylephrine (PE) or 1 microM prostaglandin F2alpha (PGF2alpha) in the presence of 0.3 microM ketanserin. EC50 values for 5-HT and alpha-methyl-5-HT relaxant responses after PE were 43.10 +/- 4.00 and 57.11 +/- 8.01 nM, respectively. pK(B) values for antagonists cyproheptadine and rauwolscine were 8.92 +/- 0.22 and 7.15 +/- 0.12, respectively. In nonprecontracted tissues, the contractile potency of 5-HT was higher in the absence of endothelium (EC50, degreesM): 2.60 +/- 0.28 and 4.12 +/- 0.21 in the absence and in the presence of endothelium, respectively. The differences were statistically significant (p<0.05). In precontracted tissues, the differences in EC50 values (2.22 +/- 0.40 and 4.65 +/- 0.60 microM without and with endothelium, respectively) were also statistically significant (p<0.05). pK(B) values for the 5-HT(2A) antagonist ketanserin were similar under all conditions tested. In conclusion, under our experimental conditions there are two functional 5-HT receptors in rat aorta: 5-HT(2A) contractile receptor in smooth muscle and a high-affinity relaxant receptor that mediates a very slight response and the pharmacology of which could be compatible with an endothelial 5-HT(2B) receptor.
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Affiliation(s)
- María Villazón
- Department of Pharmacology, School of Pharmacy, A Coruña, Spain
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7
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Brea J, Rodrigo J, Carrieri A, Sanz F, Cadavid MI, Enguix MJ, Villazón M, Mengod G, Caro Y, Masaguer CF, Raviña E, Centeno NB, Carotti A, Loza MI. New serotonin 5-HT(2A), 5-HT(2B), and 5-HT(2C) receptor antagonists: synthesis, pharmacology, 3D-QSAR, and molecular modeling of (aminoalkyl)benzo and heterocycloalkanones. J Med Chem 2002; 45:54-71. [PMID: 11754579 DOI: 10.1021/jm011014y] [Citation(s) in RCA: 44] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
A series of 52 conformationally constrained butyrophenones have been synthesized and pharmacologically tested as antagonists at 5-HT(2A), 5-HT(2B), and 5-HT(2C) serotonin receptors, useful for dissecting the role of each 5-HT(2) subtype in pathophysiology. These compounds were also a consistent set for the identification of structural features relevant to receptor recognition and subtype discrimination. Six compounds were found highly active (pK(i) > 8.76) and selective at the 5-HT(2A) receptor vs 5-HT(2B) and/or 5-HT(2C) receptors. Piperidine fragments confer high affinity at the 5-HT(2A) receptor subtype, with benzofuranone- and thiotetralonepiperidine as the most selective derivatives over 5-HT(2C) and 5-HT(2B) receptors, respectively; K(i) (2A/2C) and/or K(B) (2A/2B) ratios greater than 100 were obtained. Compounds showing a more pronounced selectivity at 5-HT(2A)/5-HT(2C) than at 5-HT(2A)/5-HT(2B) bear 6-fluorobenzisoxazolyl- and p-fluorobenzoylpiperidine moieties containing one methylene bridging the basic piperidine to the alkanone moiety. An ethylene bridge between the alkanone and the amino moieties led to ligands with higher affinities for the 5-HT(2B) receptor. Significant selectivity at the 5-HT(2B) receptor vs 5-HT(2C) was observed with 1-1[(1-oxo-1,2,3,4-tetrahydro-3-naphthyl)methyl]-4-[3-(p-fluorobenzoyl)propyl]piperazine (more than 100-fold higher). Although piperidine fragments also confer higher affinity at 5-HT(2C) receptors, only piperazine-containing ligands were selective over 5-HT(2A). Moderate selectivity was observed at 5-HT(2C) vs 5-HT(2B) (10-fold) with some compounds bearing a 4-[3-(6-fluorobenzisoxazolyl)]piperidine moiety in its structure. Molecular determinants for antagonists acting at 5-HT(2A) receptors were identified by 3D-QSAR (GRID-GOLPE) studies. Docking simulations at 5-HT(2A) and 5-HT(2C) receptors suggest a binding site for the studied type of antagonists (between transmembrane helices 2, 3, and 7) different to that of the natural agonist serotonin (between 3, 5, and 6).
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MESH Headings
- Animals
- Aorta/metabolism
- Butyrophenones/chemical synthesis
- Butyrophenones/chemistry
- Butyrophenones/pharmacology
- CHO Cells
- Cricetinae
- Cycloparaffins/chemical synthesis
- Cycloparaffins/chemistry
- Cycloparaffins/pharmacology
- Frontal Lobe/metabolism
- Heterocyclic Compounds/chemical synthesis
- Heterocyclic Compounds/chemistry
- Heterocyclic Compounds/pharmacology
- Humans
- In Vitro Techniques
- Ligands
- Male
- Models, Molecular
- Muscle, Smooth, Vascular/metabolism
- Quantitative Structure-Activity Relationship
- Rats
- Rats, Sprague-Dawley
- Receptor, Serotonin, 5-HT2A
- Receptor, Serotonin, 5-HT2B
- Receptor, Serotonin, 5-HT2C
- Receptors, Serotonin/drug effects
- Serotonin Antagonists/chemical synthesis
- Serotonin Antagonists/chemistry
- Serotonin Antagonists/pharmacology
- Stomach/drug effects
- Stomach/physiology
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Affiliation(s)
- José Brea
- Departamento de Farmacología, Facultad de Farmacia, Universidad de Santiago de Compostela, E-15782, Santiago de Compostela, Spain
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8
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López-Giménez JF, Villazón M, Brea J, Loza MI, Palacios JM, Mengod G, Vilaró MT. Multiple conformations of native and recombinant human 5-hydroxytryptamine(2a) receptors are labeled by agonists and discriminated by antagonists. Mol Pharmacol 2001; 60:690-9. [PMID: 11562430] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/21/2023] Open
Abstract
We have expanded previous studies with the 5-hydroxytryptamine (5-HT)(2) receptor agonist (+/-)-1-(2,5-dimethoxy-4-[(125)I]iodophenyl)-2-aminopropane [(+/-)-[(125)I]DOI] in human brain that had shown biphasic competition curves for several 5-HT(2A) receptor antagonists by using new selective antagonists of 5-HT(2A) (MDL100,907) and 5-HT(2C) (SB242084) receptors together with ketanserin and mesulergine. Autoradiographic competition experiments were performed with these antagonists in human brain regions where (+/-)-[(125)I]DOI labels almost exclusively 5-HT(2A) receptors (frontal cortex and striosomes). Furthermore, the effect of uncoupling receptor/G protein complexes on antagonist competition was studied with guanosine-5'-(beta,gamma-imido)triphosphate [Gpp(NH)p]. Competition experiments with (+/-)-[(3)H]1-(4-bromo-2,5-dimethoxyphenil)-2-aminopropane [(+/-)-[(3)H]DOB] were also performed in membranes from Chinese hamster ovary cells (CHOFA4) expressing cloned human 5-HT(2A) receptors. In both systems, ketanserin and MDL100,907 displayed biphasic competition profiles, whereas SB242084 and mesulergine competed monophasically. In absence of antagonist, 100 microM Gpp(NH)p decreased brain (+/-)-[(125)I]DOI specific binding by 40 to 50% and (+/-)-[(3)H]DOB specific binding to CHOFA4 cells by 30%. The remaining agonist-labeled uncoupled sites were still displaced biphasically by ketanserin and MDL100,907, with unaltered affinities. Saturation experiments were performed in CHOFA4 cells. (+/-)-[(3)H]DOB labeled two sites (K(d(h))= 0.8 nM, K(d(l)) = 31.22 nM). Addition of 100 microM Gpp(NH)p resulted in a single low-affinity (K(d) = 24.44 nM) site with unchanged B(max). [(3)H]5-HT showed no specific binding to 5-HT(2A) receptors. These results conform with the extended ternary complex model of receptor action that postulates the existence of partly activated receptor conformation(s) (R*) in equilibrium with the ground (R) and the activated G protein-coupled (R*G) conformations. Thus, both in human brain and CHOFA4 cells, the agonists possibly label all three conformations and ketanserin and MDL100,907 recognize with different affinities at least two of these conformations.
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Affiliation(s)
- J F López-Giménez
- Department of Neurochemistry, Instituto de Investigaciones Biomédicas de Barcelona-Consejo Superior de Investigaciones Cientificas, Institut d'Investigacions Biomèdiques August Pi i Sunyer, Barcelona, Spain
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