title: Articular nociception induced by endothelin-1, carrageenan and LPS in naive and previously inflamed knee-joints in the rat: inhibition by endothelin receptor antagonists.
abstract: Endothelin-1, unlike the selective endothelin ETB receptor agonist sarafotoxin S6c, causes nociception in the rat when injected intraarticularly into the naive knee-joint. By using selective antagonists, the present study further characterizes the receptors underlying the articular nociceptive actions of endothelin-1, as well as the possible contribution of endogenous endothelins towards nociception induced by carrageenan or E. coli lipopolysaccharide (LPS) in this tissue. Nociception was evaluated by placing the animal for 1 min each hour on a revolving (3 rpm) cylinder and measuring the increase in time the hindpaw of the limb affected by the intra-articular (i.a.) injection of the nociceptive agent, failed to touch its metallic surface (i.e. paw elevation time, PET). In naive joints, endothelin-1 (120 pmol) increased the area under the PET curve (AUC 0-6 h, in arbitrary units) from 61+/-3 (control) to 156+/-12. This nociceptive effect was reduced by prior intravenous (i.v.) injection of the mixed ET(A)/ET(B)receptor antagonist bosentan (by 54 and 73% with 10 and 30 mg/kg) or i.a. administration of the selective ETA receptor antagonist BQ-123 (cyclo [D-Asp-Pro-D-Val-Leu]; by approximately/= 45% with 10 or 30 nmol), but was unaffected by the selective ET(B) receptor antagonist BQ-788 (N-cis-2,6-dimethyl-piperidinocarbonyl-L-gamma-methoxycarbonyl- tryptophanil-D-norleucine; 10 nmol). Prior joint challenge with carrageenan (300 microg) 72 h beforehand (i.e. priming) rendered the joint more sensitive to nociception induced by either endothelin-1 or sarafotoxin S6c (15, 30 and 60 pmol). Responses elicited by endothelin (30 pmol) in the primed joint were sensitive to inhibition by either BQ-123 or BQ-788 (each causing approximately/= 80% inhibition at 10 nmol). Priming also enhanced PET responses to carrageenan itself and to LPS (1 microg) markedly and persistently, increasing the area under the curve (AUC 0-12 h, in arbitrary units) from 241+/-19 to 409+/-50 and from 312+/-40 to 466+/-25, respectively (P < 0.05), without changing that measured following vehicle injection (from 121+/-3 to 117+/-4). Bosentan (up to 30 mg/kg, i.v.) failed to modify nociception caused by carrageenan or LPS in naive joints, by carrageenan in the primed joint, or control PET responses. LPS-induced nociception in the primed joint, however, was inhibited by 52 to 56% by bosentan (3 or 10 mg/kg) or 59% by local injection of the selective endothelin ET(B) receptor antagonist BQ-788 (10 nmol, i.a.), but was unaffected by the selective endothelin ETA receptor antagonist BQ-123. Thus, nociception induced by endothelin-1 in the naive joint is mediated largely via endothelin ETA receptors, whereas both ET(A)and ET(B) receptors contribute to its action in the carrageenan-primed joint. Furthermore, LPS-induced nociception in the primed joint is mediated to a large extent via endothelin release and activation of ET(B) receptors within the joint itself. These findings may be relevant to the etiology of pain underlying chronic arthritic disease in humans.
authors.affiliation: Department of Pharmacology, CCB, Universidade Federal de Santa Catarina, R. Ferreira Lima 82, Florianópolis, 88015-420, SC, Brazil Department of Pharmaceutical Sciences, SEBIO, Universidade Estadual de Ponta Grossa, Ponta Grossa, 84100-000, PR, Brazil Department of Pharmacology, Faculty of Medicine, University of Sherbrooke, Sherbrooke (Québec), J1H 5N4 Canada.
authors.forename: Josélia Daher
authors.initials: JD
authors.lastname: De-Melo
authors.forename: Carlos Rogério
authors.initials: CR
authors.lastname: Tonussi
authors.forename: Pedro
authors.initials: P
authors.lastname: D'Orléans-Juste
authors.forename: Giles Alexander
authors.initials: GA
authors.lastname: Rae
mesh_terms: D000818:Animals; D000959:Antihypertensive Agents / Q000494:pharmacology; D016918:Arthritis, Reactive / Q000139:chemically induced / Q000276:immunology*; D000077300:Bosentan; D002351:Carrageenan; D004195:Disease Models, Animal; D065128:Endothelin Receptor Antagonists; D019332:Endothelin-1; D005079:Excipients; D007719:Knee Joint / Q000737:chemistry / Q000276:immunology*; D008070:Lipopolysaccharides; D008297:Male; D009619:Nociceptors / Q000187:drug effects / Q000276:immunology*; D009842:Oligopeptides / Q000494:pharmacology; D010456:Peptides, Cyclic / Q000494:pharmacology; D010880:Piperidines / Q000494:pharmacology; D051381:Rats; D017208:Rats, Wistar; D013449:Sulfonamides / Q000494:pharmacology; D014662:Vasoconstrictor Agents / Q000494:pharmacology; D014757:Viper Venoms / Q000494:pharmacology
chemical_list: D000959:Antihypertensive Agents; D065128:Endothelin Receptor Antagonists; D019332:Endothelin-1; D005079:Excipients; D008070:Lipopolysaccharides; D009842:Oligopeptides; D010456:Peptides, Cyclic; D010880:Piperidines; D013449:Sulfonamides; D014662:Vasoconstrictor Agents; D014757:Viper Venoms; C057354:sarafotoxins s6; C086539:BQ 788; D002351:Carrageenan; D000077300:Bosentan; C072247:cyclo(Trp-Asp-Pro-Val-Leu)