title: Effects of acute and chronic treatment with Hypericum perforatum L. (LI 160) on different anxiety-related responses in rats.
abstract: The study investigates the effects of acute and chronic oral treatment with Hypericum perforatum L. (HP LI 160, 62.5-500 mg/kg) in rats submitted to different anxiety models: the elevated T-maze (for inhibitory avoidance and escape measurements), the light/dark transition, and the cat odor test. These models were selected for their presumed capacity of evidencing specific subtypes of anxiety disorders as recognized in clinical practice. The results showed that acute HP (125 mg/kg) impaired elevated T-maze inhibitory avoidance, an anxiolytic effect, without altering escape performance. Chronic HP (250 mg/kg) enhanced avoidance latencies only in animals that were preexposed to the open arms of the maze. Preexposure shortens escape latency, improving it as an escape index. Differently from the reference drug imipramine (IMP, 15 mg/kg), chronic HP did not impair escape from the open arms of the maze. On the other hand, similarly to IMP, the extract increased the number of transitions between the two compartments in the light/dark transition model. Treatment regimens with HP and IMP did not alter behavioral responses of rats to a cloth impregnated with cat odor. These observations suggest that HP LI 160 exerts anxiolytic-like effects in a specific subset of defensive behaviors, particularly those related to generalized anxiety.
authors.affiliation: Laboratory of Psychopharmacology, FFCLRP, University of São Paulo, 14040-901, Ribeirão Preto, Brazil.
authors.forename: Otávio A
authors.initials: OA
authors.lastname: Flausino
authors.forename: Hélio
authors.initials: H
authors.lastname: Zangrossi
authors.forename: João V
authors.initials: JV
authors.lastname: Salgado
authors.forename: Milena B
authors.initials: MB
authors.lastname: Viana
mesh_terms: D000818:Animals; D014151:Anti-Anxiety Agents / Q000008:administration & dosage*; D000928:Antidepressive Agents / Q000008:administration & dosage; D001007:Anxiety / Q000188:drug therapy*; D001362:Avoidance Learning / Q000187:drug effects / Q000502:physiology; D002415:Cats; D003624:Darkness; D004334:Drug Administration Schedule; D004924:Escape Reaction / Q000187:drug effects / Q000502:physiology; D020902:Hypericum / Q000737:chemistry; D008027:Light; D008297:Male; D008517:Phytotherapy / Q000379:methods; D010936:Plant Extracts / Q000008:administration & dosage*; D051381:Rats; D017208:Rats, Wistar
chemical_list: D014151:Anti-Anxiety Agents; D000928:Antidepressive Agents; C422326:Hypericum extract LI 160; D010936:Plant Extracts