[Mifepristone repairs alteration of learning and memory abilities in rat model of depression].

This study is to investigate the amelioration effect of glucocorticoid receptor (GR) antagonist mifepristone on the changes of learning and memory abilities in rat model of depression. In the present study, a 35-day rat chronic unpredictable stress (CUS) model was used to observe both depression-like behaviors with sucrose preference test and open-field test and learning and memory-associated behaviors with Morris water maze test. A total of 45 male adult Sprague-Dawley rats were randomly assigned to three groups of equal size: control group (CON); CUS group (CUS); CUS + mifepristone group (CM). Animals in CM group were first exposed to CUS for 14 days, and then were administered with 50 mg x kg(-1) x d(-1) of mifepristone with continued CUS procedure. Corticosterone EIA Kit was used to detect the concentration of plasma corticosterone (CORT). Nissl staining was used to observe the structure of hippocampus. The results demonstrated that CUS exposure induced both depressive-like and learning and memory-associated behaviors and these deficits were reversed by mifepristone. Compared to CON group, the concentration of plasma CORT increased significantly in CUS group. CUS exposure damaged the structure of hippocampus, whereas mifepristone had an amelioration effect. Together, the structural deficits of hippocampus resulting from long-term stress exposure, which could contribute to the impairment of learning and memory in depression, are reversed by the GR receptor antagonist mifepristone.