title: Anxiolytic effects of repeated treatment with an essential oil from Lippia alba and (R)-(-)-carvone in the elevated T-maze.
abstract: Lippia alba (Mill.) N.E. Brown (Verbenaceae) is widely used in different regions of Central and South America as a tranquilizer. The plant's anxiolytic properties, however, merit investigation. The present study evaluated the effects of repeated daily (14 days) intraperitoneal (ip) treatment with an essential oil (EO) from a chemotype of L. alba (LA, chemotype II, 12.5 and 25 mg/kg; N = 6-8) and (R)-(-)-carvone (25 mg/kg; N = 8-12), the main constituent of this chemotype, on male Wistar rats (weighing 250 g at the beginning of the experiments) submitted to the elevated T-maze (ETM). The ETM allows the measurement of two defensive responses: inhibitory avoidance and one-way escape. In terms of psychopathology, these responses have been related to generalized anxiety and panic disorder, respectively. Treatment with the EO impaired ETM avoidance latencies, without altering escape, in a way similar to the reference drug diazepam (P < 0.05) (avoidance 2: control = 84.6 ± 35.2; EO 12.5 mg/kg = 11.8 ± 3.8; EO 25 mg/kg = 14.6 ± 2.7; diazepam = 7 ± 2.1). (R)-(-)-carvone also significantly altered this same response (P < 0.05; avoidance 1: control = 91.9 ± 31.5; carvone = 11.6 ± 1.8; diazepam = 8.1 ± 3.3). These results were not due to motor changes since no significant effects were detected in an open field. These observations suggest that LA exerts anxiolytic-like effects on a specific subset of defensive behaviors that have been implicated in generalized anxiety disorder, and suggest that carvone is one of the constituents of LA responsible for its action as a tranquilizer.
authors.affiliation: Departamento de Biociências, Universidade Federal de São Paulo, Santos, SP, Brazil.
authors.forename: V Y
authors.initials: VY
authors.lastname: Hatano
authors.forename: A S
authors.initials: AS
authors.lastname: Torricelli
authors.forename: A C C
authors.initials: AC
authors.lastname: Giassi
authors.forename: L A
authors.initials: LA
authors.lastname: Coslope
authors.forename: M B
authors.initials: MB
authors.lastname: Viana
mesh_terms: D000818:Animals; D014151:Anti-Anxiety Agents / Q000008:administration & dosage*; D001007:Anxiety / Q000188:drug therapy*; D001362:Avoidance Learning / Q000187:drug effects*; D001522:Behavior, Animal / Q000187:drug effects*; D000081005:Cyclohexane Monoterpenes; D004305:Dose-Response Relationship, Drug; D032411:Lippia / Q000737:chemistry*; D008297:Male; D039821:Monoterpenes / Q000008:administration & dosage*; D009822:Oils, Volatile / Q000008:administration & dosage*; D051381:Rats; D017208:Rats, Wistar
chemical_list: D014151:Anti-Anxiety Agents; D000081005:Cyclohexane Monoterpenes; D039821:Monoterpenes; D009822:Oils, Volatile; C006923:carvone