Introduction: Some studies indicated that the decrease of estrogen level in menopausal woman results in increasing the risk of stroke. Although estrogen is a neuroprotective factor, high consumption of this compound may develop breast cancer and endometriosis. The present study investigated the effect of Achilles millefolium extract, containing estrogenlike compounds, on memory impairment and anxiogenic-like behaviors caused by cerebral ischemia in ovariectomized rats. Methods: Permanent middle cerebral artery ligation was performed, as a model for studying postmenopausal condition, in 48 female Wistar rats weighing 200-250 g. The aqueous extract of A. millefolium was prepared and gavaged for 4 weeks after inducing cerebral ischemia. Memory and anxiety-like behavior assessments were evaluated by step-through and elevated plus maze apparatus, respectively. Result: According to the results, cerebral ischemia in ovariectomized rats induced amnesia and anxiogenic-like behaviors which were restored by 7 mg/kg of A. millefolium aqueous extract. Furthermore, inactivation of estrogen receptors (ERs) by tamoxifen (100 µg/kg, intraperitoneally) blocked the restoration effect of A. millefolium on behaviors induced by cerebral ischemia. Conclusion: It could be concluded that, oral administration of A. millefolium extract is able to restore memory impairment and anxiogenic-like behaviors induced by ischemia via ERs in ovariectomized rat.
Keywords: Achillea Millefolium, Cerebral ischemia, Memory, Anxiety, Ovariectomy