Effects of aromatase inhibition on spatial working memory and hippocampal astrocyte numbers

Sex hormones are known to induce the sexual differentiation of the brain during early development in mammals. Testosterone secreted by males already during gestation is classically believed to contribute to brain and behavioural sexual differentiation thanks to its conversion to estradiol by the enzyme aromatase. However, there is evidence suggesting that aromatase inhibition may also impair cognitive functions in women receiving hormonal treatment for breast cancer. In order to evaluate the effects of aromatase on brain and behaviour, male and female prepubescent rats treated with anastrozole prenatally and during early postnatal development were tested in a spatial working memory task. Results show that anastrozole treatment clearly impaired spatial working memory in male and female rats as compared to sex-matched vehicle-treated and control groups. In addition, the number of astrocytes expressing glial fibrillary acidic protein (GFAP) decreased in the CA3 area of the dorsal hippocampus only in male rats. These results indicate that aromatase plays a complex role on the sexual differentiation of the brain and affects spatial memory in males and females.