title: Involvement of 5-HT2 receptors in the antinociceptive effect of Uncaria tomentosa.
abstract: Uncaria tomentosa (Willd.) DC (Rubiaceae) is a vine that grows in the Amazon rainforest. Its bark decoctions are used by Peruvian Indians to treat several diseases. Chemically, it consists mainly of oxindole alkaloids. An industrial fraction of U. tomentosa (UT fraction), containing 95% oxindole alkaloids, was used in this study in order to characterize its antinociceptive activity in chemical (acetic acid-induced abdominal writhing, formalin and capsaicin tests) and thermal (tail-flick and hot-plate tests) models of nociception in mice. UT fraction given by the i.p. route dose-dependently suppressed the behavioural response to the chemical stimuli in the models indicated and increased latencies in the thermal stimuli models. The antinociception caused by UT fraction in the formalin test was significantly attenuated by i.p. treatment of mice with ketanserin (5-HT2 receptor antagonist), but was not affected by naltrexone (opioid receptor antagonist), atropine (a nonselective muscarinic antagonist), l-arginine (precursor of nitric oxide), prazosin (alpha1-adrenoceptor antagonist), yohimbine (alpha2-adrenoceptor antagonist), and reserpine (a monoamine depleter). Together, these results indicate that UT fraction produces dose-related antinociception in several models of chemical and thermal pain through mechanisms that involve an interaction with 5-HT2 receptors.
authors.affiliation: Departamento de Farmacologia, Universidade Federal de Santa Catarina, Florianópolis, Santa Catarina, Brazil.
authors.forename: Sofia
authors.initials: S
authors.lastname: Jürgensen
authors.forename: Sílvia
authors.initials: S
authors.lastname: Dalbó
authors.forename: Paul
authors.initials: P
authors.lastname: Angers
authors.forename: Adair Roberto Soares
authors.initials: AR
authors.lastname: Santos
authors.forename: Rosa Maria
authors.initials: RM
authors.lastname: Ribeiro-do-Valle
mesh_terms: D019342:Acetic Acid; D000700:Analgesics / Q000494:pharmacology*; D000818:Animals; D001120:Arginine / Q000494:pharmacology; D001285:Atropine / Q000494:pharmacology; D001522:Behavior, Animal / Q000187:drug effects; D002211:Capsaicin; D020948:Cat's Claw; D004305:Dose-Response Relationship, Drug; D005557:Formaldehyde; D007650:Ketanserin / Q000494:pharmacology; D008297:Male; D051379:Mice; D009043:Motor Activity / Q000187:drug effects; D009271:Naltrexone / Q000494:pharmacology; D010146:Pain / Q000139:chemically induced / Q000517:prevention & control; D010147:Pain Measurement / Q000379:methods; D008517:Phytotherapy; D028321:Plant Preparations / Q000494:pharmacology*; D011224:Prazosin / Q000494:pharmacology; D044348:Receptors, Serotonin, 5-HT2 / Q000502:physiology*; D012110:Reserpine / Q000494:pharmacology; D058830:Serotonin 5-HT2 Receptor Antagonists; D012702:Serotonin Antagonists / Q000494:pharmacology; D015016:Yohimbine / Q000494:pharmacology
chemical_list: D000700:Analgesics; D028321:Plant Preparations; D044348:Receptors, Serotonin, 5-HT2; D058830:Serotonin 5-HT2 Receptor Antagonists; D012702:Serotonin Antagonists; D005557:Formaldehyde; D015016:Yohimbine; D009271:Naltrexone; D001285:Atropine; D012110:Reserpine; D001120:Arginine; D007650:Ketanserin; D019342:Acetic Acid; D002211:Capsaicin; D011224:Prazosin