Effects of endothelin-1 on capsaicin-induced nociception in mice.
The influence of endothelin-1 on nociception induced by capsaicin was assessed in the mouse hindpaw. Local endothelin-1 injection (1 to 20 pmol/paw) 30 min prior to ipsilateral injection of capsaicin (0.1 microg/paw) increased, in a graded fashion, the time spent licking the injected paw. Maximal hyperalgesia was obtained with 10 pmol/paw of endothelin-1 (capsaicin-induced hindpaw licking time increased from 43 +/- 3 s to 114 +/- 7 s, n = 6), but no hyperalgesia was evident following 30 pmol/paw of endothelin-1. The selective endothelin ET(B) receptor agonists sarafotoxin S6c (< or = 30 pmol/paw) and IRL 1620 (i.e., Suc[Glu9,Ala11,15]endothelin-1-(10-21); < or = 100 pmol/paw) failed to induce hyperalgesia. Local treatment with BQ-123 (i.e., cyclo[DTrp-DAsp-Pro-DVal-Leu] 1 nmol/paw selective endothelin ET(A) receptor antagonist), 10 min before endothelin-1 (10 pmol/paw), fully blocked the hyperalgesic response, whereas similar treatment with the selective endothelin ET(B) receptor antagonist BQ-788 (i.e., N-cis-2,6-dimethylpiperidinocarbonyl-L-gamma-methylleucyl-D- 1-methoxy-carboyl-D-norleucine) was ineffective. Intravenous injection of bosentan (17 and 52 micromol/kg a non-peptidic mixed endothelin ET(A)/ET(B) receptor antagonist) or BMS 182874 (i.e., 5-[dimethylamino]-N-[3,4-dimethyl-5-isoxazolyl]-1-naphthalenesulph onamide; 10 and 30 micromol/kg; a non-peptidic selective endothelin ET(A) receptor antagonist), 1 h before endothelin-1, inhibited its hyperalgesic effect in a graded fashion and abolished the response at the higher doses. None of the antagonists modified nociception induced by capsaicin alone or the hyperalgesia induced by local injection of 5-hydroxytryptamine (5-HT; 2 nmol/paw, 30 min before capsaicin). Hyperalgesia induced by 5-HT was abolished by simultaneous injection of endothelin-1 or the endothelin ET(B) receptor agonist IRL 1620 (each at 30 pmol/paw). Therefore, local endothelin-1 exerts a dual influence in this model: at low doses it causes endothelin ET(A) receptor-mediated hyperalgesia (i.e., it potentiates capsaicin-induced nociception), whereas at higher doses it induces an anti-hyperalgesic effect against 5-HT which seems to be mediated via distinct endothelin ET (possibly ET(B)) receptors.
Piovezan
A P
AP
Department of Pharmacology, CCB, Universidade Federal de Santa Catarina, Florianópolis, Brazil.
D'Orléans-Juste
P
P
Tonussi
C R
CR
Rae
G A
GA
D000698:Analgesia; D000818:Animals; D000077300:Bosentan; D002211:Capsaicin; D003619:Dansyl Compounds / Q000494:pharmacology; D004305:Dose-Response Relationship, Drug; D065128:Endothelin Receptor Antagonists; D019332:Endothelin-1 / Q000008:administration & dosage / Q000494:pharmacology*; D016232:Endothelins / Q000494:pharmacology; D006614:Hindlimb; D006930:Hyperalgesia / Q000139:chemically induced / Q000188:drug therapy*; D008297:Male; D051379:Mice; D009842:Oligopeptides / Q000494:pharmacology; D010446:Peptide Fragments / Q000494:pharmacology; D010455:Peptides / Q000494:pharmacology; D010456:Peptides, Cyclic / Q000494:pharmacology; D010880:Piperidines / Q000494:pharmacology; D044022:Receptor, Endothelin A; D044023:Receptor, Endothelin B; D017466:Receptors, Endothelin / Q000819:agonists; D012701:Serotonin / Q000494:pharmacology; D013449:Sulfonamides / Q000494:pharmacology; D014757:Viper Venoms
D003619:Dansyl Compounds; D065128:Endothelin Receptor Antagonists; D019332:Endothelin-1; D016232:Endothelins; D009842:Oligopeptides; D010446:Peptide Fragments; D010455:Peptides; D010456:Peptides, Cyclic; D010880:Piperidines; D044022:Receptor, Endothelin A; D044023:Receptor, Endothelin B; D017466:Receptors, Endothelin; D013449:Sulfonamides; D014757:Viper Venoms; C089502:sarafotoxin-c; C074308:sovateltide; C085754:5-(dimethylamino)-N-(3,4-dimethyl-5-isoxazolyl)-1-naphthalenesulfonamide; D012701:Serotonin; C086539:BQ 788; D000077300:Bosentan; D002211:Capsaicin; C072247:cyclo(Trp-Asp-Pro-Val-Leu)