title: Analysis of the antinociceptive effect of the proanthocyanidin-rich fraction obtained from Croton celtidifolius barks: evidence for a role of the dopaminergic system.
abstract: In a previous study, we demonstrated the antinociceptive effect of 63SF, a proanthocyanidin-rich fraction obtained from Croton celtidifolius barks, in chemical and thermal behavioural models of pain in mice. The current study now investigate the possible mechanisms underlying the antinociceptive activity of 63SF in the formalin test, by using drugs which interfere with systems that are implicated in descending control of nociception. The antinociceptive effect of 63SF (11 mg/kg, i.p., given 30 min prior to 2.5% formalin) was not altered by pre-treatment of animals 45-50 min beforehand with either prazosin (alpha(1)-adrenergic antagonist; 0.15 mg/kg, i.p.), yohimbine (alpha(2)-adrenergic antagonist; 0.15 mg/kg, i.p.), ketanserin (5-HT(2A)-receptor antagonist; 1.0 mg/kg, i.p.), or l-arginine (substrate for NO synthase, 600 mg/kg, i.p.). On the other hand, treatment with sulpiride, an antagonist of dopaminergic D(2)-receptors (1.0 mg/kg, i.p., 45 min of pre-treatment), reversed the antinociceptive activity of 63SF. Pre-treatment of animals with reserpine (5 mg/kg, i.p., 24 h beforehand) did not alter the antinociceptive effect of 63SF. The current results support the view that the 63SF exerts antinociceptive effects by enhancing the activity of descending control, possibly by direct stimulation of dopaminergic D(2) receptors.
authors.affiliation: Departamento de Farmacologia, Centro de Ciências Biológicas, Bloco D, UFSC, Campus Universitário, Trindade, Florianópolis, SC, CEP 88040-900, Brazil.
authors.forename: Silvia
authors.initials: S
authors.lastname: DalBó
authors.forename: Sofia
authors.initials: S
authors.lastname: Jürgensen
authors.forename: Heros
authors.initials: H
authors.lastname: Horst
authors.forename: Douglas Nihues
authors.initials: DN
authors.lastname: Soethe
authors.forename: Adair Roberto Soares
authors.initials: AR
authors.lastname: Santos
authors.forename: Moacir Geraldo
authors.initials: MG
authors.lastname: Pizzolatti
authors.forename: Rosa Maria
authors.initials: RM
authors.lastname: Ribeiro-do-Valle
mesh_terms: D000700:Analgesics / Q000494:pharmacology*; D000818:Animals; D001120:Arginine / Q000494:pharmacology; D029802:Croton / Q000737:chemistry*; D008297:Male; D051379:Mice; D009569:Nitric Oxide / Q000502:physiology; D010936:Plant Extracts / Q000494:pharmacology*; D011224:Prazosin / Q000494:pharmacology; D044945:Proanthocyanidins / Q000494:pharmacology*; D017448:Receptors, Dopamine D2 / Q000502:physiology*; D013469:Sulpiride / Q000494:pharmacology; D015016:Yohimbine / Q000494:pharmacology
chemical_list: D000700:Analgesics; D010936:Plant Extracts; D044945:Proanthocyanidins; D017448:Receptors, Dopamine D2; C013221:proanthocyanidin; D015016:Yohimbine; D009569:Nitric Oxide; D013469:Sulpiride; D001120:Arginine; D011224:Prazosin