title: δ-Opioid receptor agonist SNC80 induces central antinociception mediated by Ca2+ -activated Cl- channels.
abstract: OBJECTIVE
  The aim of this study was to determine whether Ca(2+)-activated Cl(-) channels (CaCCs) are involved in central antinociception induced by the activation of µ-, δ- and κ-opioid receptors.
  
  
  METHODS
  The nociceptive threshold for thermal stimulation was measured using the tail-flick test in Swiss mice. The drugs were administered via the intracerebroventricular route. Probabilities values of P < 0.05 were considered to be statistically significant (analysis of variance/Bonferroni test).
  
  
  RESULTS
  The results demonstrate that exposure to the CaCC blocker niflumic acid (2, 4 and 8 µg) partially reverses the central antinociception induced by the δ-opioid receptor agonist SNC80 ((+)-4-[(αR)-α-((2S,5R)-4-allyl-2,5-dimethyl-1-piperazinyl)-3-methoxybenzyl]-N,N-diethylbenzamide; 4 µg). In contrast, niflumic acid did not modify the antinociceptive effect of the µ-opioid receptor agonist [D-Ala(2), N-Me-Phe(4), Gly(5)-ol]-enkephalin (0.5 µg) or κ-opioid receptor agonist bremazocine (4 µg).
  
  
  CONCLUSIONS
  These data provide evidence for the involvement of CaCCs in δ-opioid receptor-induced central antinociception resulting from receptor activation by the agonist SNC80. CaCC activation does not appear to be involved when µ- and κ-opioid receptors are activated.
authors: Department of Pharmacology, Institute of Biological Sciences, Federal University of Minas Gerais             School of Biological Sciences and Health, University Center Newton Paiva, Belo Horizonte, Brazil.
authors: Daniela da Fonseca
authors: Dda F
authors: Pacheco
authors: Cinthia Mara da Fonseca
authors: CM
authors: Pacheco
authors: Igor Dimitri Gama
authors: ID
authors: Duarte
mesh_terms: D000701:Analgesics, Opioid / Q000494:pharmacology* / Q000627:therapeutic use; D000818:Animals; D001549:Benzamides / Q000494:pharmacology* / Q000627:therapeutic use; D001575:Benzomorphans / Q000494:pharmacology; D002118:Calcium / Q000378:metabolism*; D002412:Cations / Q000378:metabolism; D018118:Chloride Channels / Q000378:metabolism*; D004745:Enkephalins / Q000494:pharmacology; D006358:Hot Temperature; D008297:Male; D051379:Mice; D008815:Mice, Inbred Strains; D009544:Niflumic Acid / Q000494:pharmacology; D010146:Pain / Q000188:drug therapy* / Q000378:metabolism; D017288:Pain Threshold / Q000187:drug effects; D010879:Piperazines / Q000494:pharmacology* / Q000627:therapeutic use; D017465:Receptors, Opioid, delta / Q000819:agonists*; D017473:Receptors, Opioid, kappa / Q000819:agonists; D017450:Receptors, Opioid, mu / Q000819:agonists
chemical_list: D000701:Analgesics, Opioid; D001549:Benzamides; D001575:Benzomorphans; D002412:Cations; D018118:Chloride Channels; D004745:Enkephalins; D010879:Piperazines; D017465:Receptors, Opioid, delta; D017473:Receptors, Opioid, kappa; D017450:Receptors, Opioid, mu; C088464:4-(alpha-(4-allyl-2,5-dimethyl-1-piperazinyl)-3-methoxybenzyl)-N,N-diethylbenzamide; D009544:Niflumic Acid; C027248:bremazocine; D002118:Calcium