Tamoxifen and toremifene impair retrieval, but not acquisition, of spatial information processing in mice

The present study examines the effects of tamoxifen (TAM) or toremifene (TOR), two triphenylethylene antiestrogen agents, on spatial information in mice by using Morris water maze. In a 30-s free swim trial, the TAM- or TOR-treated mice (intraperitoneally, 30 min before test) spent shorter time than the blank control mice in target quadrant. Compared to saline control group, animals exposed to TAM (1-10 mg/kg i.p., once a day for 5 days) or TOR (3-30 mg/kg i.p., once a day for 5 days) did not show significant difference on the acquisition of place task in Morris water maze. These results suggest that TAM, at the doses of 1-10 mg/kg, and TOR, at the doses of 3-30 mg/kg, impair the retrieval, but not the acquisition, of spatial information task in Morris water maze. It seems, however, that TOR is more potent than TAM on impairing memory retrieval.