Efects of hormone replacement and tamoxifen on depression in ovariectomized rats.

OBJECTIVES To determine the effects of tamoxifen and hormone replacement therapy in order to assess their role in depressive behavior: MATERIAL AND METHODS Different protocols of hormone replacement therapies were administered to surgically ovariectomized rats. Intact rats were used for tamoxifen experiments. Properly assigned control groups were used and cognitive processes were studied on animal models of surgical menopause using the Porsolt forced swim test and locomotor activity experiments. RESULTS In the tamoxifen experiments, an interaction between treatment and days did not reach statistical significance, but indicated a trend in this direction [F(1,26)=3.557, p = 0.071]. The number of repeated movements significantly decreased after the Porsolt test (F(1,44) = 8.483, P < 0.006) in the hormone replacement experiments. In the tamoxifen experiments, the number of repeated movements significantly decreased after the Porsolt test (F(1,26) = 74.410, P < 0.001). CONCLUSIONS While sequential hormone replacement is found to be protective against depression, tamoxifen seems to augment behavioral despair