Correlation between Serum Estrogen and Spatial Memory in Peripartal Rats

Park, Min Sung; Park, Je Min; Shin, Sung Hyun; Han, Kwi Won; Kim, Myung Jung; Kim, Sung Gon \

Abstract

OBJECTIVES
This study was designed to find possible effect of pregnancy and parturition on spatial memory, especially in relation to levels of estrogen during the third trimester and postpartal period in rats.
METHODS
25 female Sprague Dawley rats were divided into pregnant group (N=14) and control group (N=11). Changes in spatial memory during 6 weeks including third trimester and postpartal period were measured using Morris water maze. Time to reach the platform in the maze was indicator of spatial memory. Serum estrogen level was measured on 1 week before delivery, postpartal day 1, and day 14.
RESULTS
Both groups showed gradual improvement in performance by trial days and weeks, but no significant difference was found between the two groups. However in the third trimester, pregnant group showed a trend of less achievement on 3 days of learning than control group. Serum estrogen levels did not differ significantly between groups over the 6 weeks of period. However there was positive correlation between serum estrogen level on postpartum day 1 and time to reach platform on postpartum week 2, and negative correlation between estrogen level on postpartum day 14 and latency to the platform on postpartum week 5.
CONCLUSION
These results imply that changes in the serum estrogen level may have dual effects on the spatial learning in peripartal period. It is suggested that decline in cognitive function might occur either by failure of rapid decrease of estrogen, immediately after parturition, or retarded restoration of estrogen in later postpartal period.