Abstract:

Objective To investigate the effects of estradiol on behavior and expression of serotonin transporter (SERT) protein in hippocampus and amygdala in bilaterally ovariectomized rats in forced swimming test. Methods Twenty-eight adult female SD rats were randomly divided into control group, stress group, estradiol group and fluoxetine group (n=7). Three weeks after bilateral ovariectomy, drugs were administered to rats for 14 d. On the fourteenth day of administration, rats in stress group, estradiol group and fluoxetine group were subjected to 15 min forced swimming test, and the behavior of rats was evaluated. The expression of SERT in hippocampus and amygdala of rats in each group was determined by immunofluorescence histochemical method. Results In forced swimming test, the counts of swimming behavior in estradiol group and fluoxetine group were significantly more than that in stress group, while the counts of immobility behavior in estradiol group and fluoxeitne group were significantly less than that in stress group (P<0.001 for all). Immunofluorescence histochemistry indicated that the integral absorbance of SERT in hippocampus and amygdala in stress group was significantly higher than that in control group (P<0.001), while the integral absorbance of SERT in hippocampus and amygdala in estradiol group and fluoxeitne group was significantly lower than that in stress group (P<0.05, P<0.001). Conclusion Estradiol may increase the counts of swimming behavior and decrease the counts of immobility behavior of bilaterally ovariectomized rats in forced swimming test. Pretreatment with estradiol may inhibit stress-induced content increase of SERT protein in hippocampus and amygdala, which resembles the effects of antidepressant fluoxetine.

Key words: estradiol, fluoxetine, forced swimming test, serotonin transporter, immunofluorescence histochemistry