OBJECTIVES: To compare the effect exerted by oral tibolone or intramuscular 17β-estradiol administration on the expression of ZO-1, occludin, GFAP and c-fos levels in the brain cortex and hippocampus of ovariectomized rats.
RESULTS: Immunostaining for ZO-1 and occludin revealed similar staining patterns between controls and tibolone rats and between controls and E2 rats. When staining in tibolone and E2 rats were compared both for ZO-1 and occludin, staining patterns were again identical. Positive staining for the GFAP was detected in the controls, tibolone rats and E2 rats. Staining was more intense in the tibolone rats than controls and in the E2 rats than controls. In sections from the controls, tibolone rats and E2 rats, number of reactive cells for c-fos were 1.75±0.25, 3.75±0.36 and 4.50±0.50, respectively. There was a statistically significant difference between the three groups (p=0.0001). Comparison of tibolone and E2 rats revealed no statistically significant difference (p=0.246).
CONCLUSIONS: It is well known that natural hormones like E2 regulate brain development and function. Our results provide further information on the mechanism of action of tibolone in the brain cortex and hippocampus. These results will allow us to continue with further studies with different post-ovariectomy intervals, because tibolone can be proposed as an attractive alternative for hormone replacement therapy, acting as a neuroprotective agent for the prevention of neurodegenerative diseases in menopausal women.