Anxiolytic-like effects of acute and chronic treatment with Achillea millefolium L. extract

Ethnopharmacological relevance

Achillea millefolium L. (Asteraceae), known as yarrow (“mil folhas”), has been used as folk medicine for gastrointestinal disorders, inflammation, anxiety, and insomnia.

Aim

To evaluate the potential anxiolytic-like effect of hydroalcoholic extract of Achillea millefolium L. in animal models.

Methods

The present study evaluated the effects of the hydroalcoholic extract from the aerial parts of Achillea millefolium L. in mice subjected to the elevated plus-maze, marble-burying, and open-field tests. Additionally, the GABA_A/benzodiazepine (BDZ) mediation of the effects of Achillea millefolium was evaluated by pretreatment with the noncompetitive GABA_A receptor antagonist picrotoxin and the BDZ antagonist flumazenil and by ³H]-flunitrazepam binding to the BDZ site on the GABA_A receptor.

Results

Achillea millefolium exerted anxiolytic-like effects in the elevated plus-maze and marble-burying test after acute and chronic (25 days) administration at doses that did not alter locomotor activity. This behavioral profile was similar to diazepam. The effects of Achillea millefolium in the elevated plus-maze were not altered by picrotoxin pretreatment but were partially blocked by flumazenil. Furthermore, Achillea millefolium did not induce any changes in ³H]-flunitrazepam binding.

Conclusion

The results indicate that the orally administered hydroalcoholic extract of Achillea millefolium L. exerted anxiolytic-like effects that likely were not mediated by GABA_A/BDZ neurotransmission and did not present tolerance after short-term, repeated administration.