Anticonflict actions of aqueous extracts of flowers of Achillea millefolium L. vary according to the estrous cycle phases in Wistar rats.

Anticonflict-like effects of aqueous extract of flowers of Achillea millefolium L., a plant with purported anxiolytic actions, were studied in female Wistar rats during late proestrus or diestrus. During late proestrus (p < 0.05), control rats displayed reduced conflict behavior compared with diestrus. Diazepam (2.0 mg/kg; i.p.) reduced conflict behavior both during late proestrus (p < 0.05) or diestrus (p < 0.05). Doses of 8.0 mg/kg (p < 0.05), 10.0 mg/kg (p < 0.05) or 12.0 mg/kg (p < 0.05) of Achillea millefolium reduced conflict behavior during late proestrus. Conversely, during diestrus, only the dose of 12.0 mg/kg (p < 0.05) of Achillea millefolium L. reduced conflict behavior. In conclusion, the anticonflict-like actions of Achillea millefolium L. may vary according to the estrous cycle phase. Copyright 2004 John Wiley & Sons, Ltd.