Effects of Hypericum perforatum and paroxetine in the mouse defense test battery

Since (a) Hypericum perforatum shows anxiolytic-like effect in some animal models, (b) antidepressant drugs (AD) have been used as the main drug treatment for panic disorder (PD), (c) AD are also effective in generalized anxiety disorder (GAD), and (d) H. perforatum exhibits antidepressant activity, it was hypothesized that H. perforatum might possess an antipanic-like and/or anxiolytic-like effect. Previous studies with the mouse defense test battery (MDTB) have suggested that this model may be useful for the investigation of anxiolytic-like and antipanic-like compounds. Thus, the aim of the present study was to evaluate the effect of H. perforatum extract in the MDTB. The effect of acute, subchronic (7 days), and chronic (21 days) H. perforatum (150 and 300 mg/kg) extract administration was evaluated in mice submitted to the MDTB. Paroxetine (5 mg/kg), a selective serotonin re-uptake inhibitor with anxiolytic and antipanic effect, was used as a positive control. The results showed that 21 days of repeated administration of H. perforatum 300 mg/kg and paroxetine 5 mg/kg reduced flight reactions (number of avoidances, avoidance distance, and overall flight speed) to the presence of the predator. While the effect of paroxetine confirms that MDTB is useful for the detection of antipanic-like drugs, the effect of H. peiforatum suggests a putative antipanic-like effect for this extract. Moreover, after 21 days of repeated administration, paroxetine increased the number of approaches/withdrawals and reduced the number of upright postures, suggesting a partial anxiolytic-like effect, while H. perforatum only reduced the number of upright postures. The present results suggest anxiolytic-like and antipanic-like effects of H. perforatum extract. However, it should be emphasized that the risk assessment (the main index of anxiety) was not affected by the extract, while the attack reactions were only weakly modified. (C) 2003 Elsevier Science Inc. All rights reserved.