Effects of Hypericum perforatum and paroxetine on rat performance in the elevated T-maze.
Hypericum perforatum extract exhibits an antidepressant effect and since several antidepressant drugs are also effective on generalised anxiety disorder (GAD) and panic disorders (PD), H. perforatum may possess some anxiolytic/antipanic effect. Thus, the aim of the present study was to evaluate the putative antipanic/anxiolytic effect of standardised H. perforatum extract (LI 160) on rats tested in the elevated T-maze, an animal model of innate (panic) and learned (generalised) anxiety, at doses that exhibit antidepressant-like activity. H. perforatum (150, 300 and 500 mg/kg, administered orally 24, 18 and 1h before the test) decreased the immobility time in the forced swim test. Rats were treated orally with H. perforatum (150 or 300 mg/kg) or paroxetine (5mg/kg) 24, 18, and 1h before being tested in the elevated T-maze (subacute treatment). Immediately after this test, the animals were submitted to the open field to evaluate locomotor activity. Paroxetine was used as a positive control, since it was clinically effective in GAD and PD. Other groups of animals were submitted to the same drug treatment for 7 days (subchronic treatment). Paroxetine (5mg/kg) impaired inhibitory avoidance after subacute treatment, while subchronic administration increased one-way escape latency. Subacute treatment with H. perforatum (300 mg/kg) exerts a partial anxiolytic-like effect in the inhibitory avoidance task. Repeated administration of H. perforatum (300 mg/kg) induced an anxiolytic effect (decreased inhibitory avoidance) and an antipanic effect (increased one-way escape). No effect on locomotor activity was found with any treatment. Thus, the results suggest that H. perforatum extract could exert an anxiolytic and antipanic effect.
Beijamini
Venessa
V
Departamento de Farmacologia, Laboratório de Fisiologia e Farmacologia do Sistema Nervoso Central, Setor de Ciências Biológicas, Centro Politécnico, Universidade Federal do Paraná, P.O. Box 19031, 81531-990, PR, Curitiba, Brazil.
Andreatini
Roberto
R
D000704:Analysis of Variance; D000818:Animals; D001007:Anxiety / Q000188:drug therapy*; D001362:Avoidance Learning / Q000187:drug effects; D004334:Drug Administration Schedule; D020902:Hypericum; D008297:Male; D018782:Maze Learning / Q000187:drug effects*; D010200:Panic / Q000187:drug effects*; D016584:Panic Disorder / Q000188:drug therapy; D017374:Paroxetine / Q000494:pharmacology*; D010936:Plant Extracts / Q000008:administration & dosage / Q000494:pharmacology* / Q000627:therapeutic use; D051381:Rats; D017208:Rats, Wistar; D017367:Selective Serotonin Reuptake Inhibitors / Q000494:pharmacology*; D013550:Swimming
D017374:Paroxetine; D010936:Plant Extracts; D017367:Selective Serotonin Reuptake Inhibitors