ABSTRACT OBJECTIVE: The present study aimed at examining the effects of regular exercise on hippocampal estrogen and estrogen receptor β (ERβ) levels, as well as the spatial memory of ovariectomized rats. BACKGROUND: A decrease of estrogen levels leads to dysfunctions of hippocampus, including spatial learning and memory. Studies have shown that physical exercise improved spatial memory of ovariectomized rats and was associated with an increased extragonadal aromatization. This in turn affects the expression of estrogen receptors. METHODS: Ovariectomized Sprague Dawley rats were randomly assigned into the two groups, i.e. exercise and control groups. Rats of the exercise group were trained to run on a treadmill. The exercise was performed fi ve times per week for 12 weeks. The spatial memory of rats was measured using the Morris water maze. The hippocampal estrogen and ERβ levels of rats were determined using ELISA. RESULTS: The spatial memory retention of the exercise group was signifi cantly better than that of the control group. The hippocampal estrogen level of the exercise group was signifi cantly higher than that of the control group. CONCLUSION: Regular exercise increases hippocampal estrogen levels and improves spatial memory retention of ovariectomized rats (Tab. 1, Fig. 4, Ref. 53). Text in PDF ww