RESUMO
OBJECTIVE: The purpose of this study is to investigate the effect of chronic deprivation of estradiol on the serotonin level in Sprague-Dawley rat's cerebral cortex and hippocampus. METHODS: One hundred of female Sprague-Dawley rats were taken care for seven to eight weeks, then they were randomly assigned into two group; fifty rats underwent bilateral oophorectomy & the remaining rats were the control group. Six months after oophorectomy, brain tissue was extracted from cerebral cortex and hippocampus and then homogenated: this was done in the both groups. The upper layer of the homogenated substance was taken and frozen and finally dried up. The next process was marking with PITC, quantification through HPLC and comparing with authentic serotonin. Protein quantity was measured by using Bradford method. RESULTS: Comparison between the bilateral oophorectomy group and the control group for serotonin content in the cerebral cortex was 134.2+/-14.3 nmol/mg protein(mean+/-SEM) and 122.5+/-11.6 nmol/mg protein in each group. As for the serotonin content in the hippocampus was 148.8+/-13.9 nmol/mg protein and 132.9+/-13.7 nmol/mg protein in each group. It shows that, there was no significant difference in the serotonin level, in the two areas mentioned above. CONCLUSION: The effect of estradiol on the serotonin level may be dependent on the hormonal change duration. Chronic effect of hypoestrogenism might have no effect on tryptophan hydroxylase and monoamine oxidase, thus not changin the serotonin level. These data supported the previous findings that chronic hypoestrogenism had no effect on serotonin level.