title: Do endogenous opioids and nitric oxide participate in the anticonvulsant action of dipyrone?
abstract: It was previously reported that systemic administration of dipyrone inhibited the tonic component of generalized tonic-clonic seizures in both the electroshock and the audiogenic seizure models. The aim of the present study was to investigate the mechanisms involved in the anticonvulsant action of dipyrone by assessing the role of nitric oxide and opioids in the electroshock (female 60- to 90-day-old Wistar rats, N = 5-11) and audiogenic seizure (female 60- to 90-day-old Wistar audiogenic rats, N = 5-11) models of epilepsy. Naloxone (5 mg/kg, sc) significantly reversed the anticonvulsant effect of dipyrone in rats submitted to the induction of audiogenic seizures (ANOVA/Bonferroni's test), suggesting the involvement of opioid peptides in this action. In the electroshock model no reversal of the anticonvulsant effect of dipyrone by naloxone (5 mg/kg, sc) was demonstrable. The acute (120 mg/kg, ip) and chronic (25 mg/kg, ip, twice a day/4 days) administration of L-NOARG did not reverse the anticonvulsant action of dipyrone in the audiogenic seizure model, suggesting that the nitric oxide pathway does not participate in such effect. Indomethacin (10, 20 and 30 mg/kg, ip) used for comparison had no anticonvulsant effect in the audiogenic seizure model. In conclusion, opioid peptides but not nitric oxide seem to be involved in the anticonvulsant action of dipyrone in audiogenic seizures.
authors.affiliation: Departamento de Farmacologia, Instituto de Ciências Biológicas, Universidade Federal de Minas Gerais, Belo Horizonte, MG, Brasil.
authors.forename: G M L
authors.initials: GM
authors.lastname: Reis
authors.forename: M C
authors.initials: MC
authors.lastname: Doretto
authors.forename: I D G
authors.initials: ID
authors.lastname: Duarte
authors.forename: M A K F
authors.initials: MA
authors.lastname: Tatsuo
mesh_terms: D000818:Animals; D000927:Anticonvulsants / Q000494:pharmacology* / Q000627:therapeutic use; D004177:Dipyrone / Q000494:pharmacology* / Q000627:therapeutic use; D004597:Electroshock; D020195:Epilepsy, Reflex / Q000188:drug therapy* / Q000378:metabolism; D005260:Female; D009270:Naloxone / Q000494:pharmacology; D009292:Narcotic Antagonists / Q000494:pharmacology; D009569:Nitric Oxide / Q000037:antagonists & inhibitors / Q000502:physiology*; D019335:Nitroarginine / Q000494:pharmacology; D018847:Opioid Peptides / Q000502:physiology*; D011453:Prostaglandins / Q000502:physiology*; D051381:Rats; D017208:Rats, Wistar
chemical_list: D000927:Anticonvulsants; D009292:Narcotic Antagonists; D018847:Opioid Peptides; D011453:Prostaglandins; D019335:Nitroarginine; D009569:Nitric Oxide; D009270:Naloxone; D004177:Dipyrone