Sex chromosome complement determines sex differences in aromatase expression and influences aromatase regulation by gonadal hormones in developing neurons

CAMBIASSO, M.J.

Mendoza

Workshop; 2015 International Workshop in Neuroendocrinology; 2015

Thecurrent model of sexual differentiation involves genetic factors encoded by sexchromosomes acting in parallel with gonadal factors. We evaluated the role of sex chromosome complement onthe generation of sexdifferences in the expression of aromatase in specific brain regions in mouseembryos at E16. For this study we used the "four core genotypes" mouse model, in whichthe effect of gonadal sex and sex chromosome complement is dissociated. The brain of XY embryos showed higher levels of aromatase expression inthe stria terminalis and the anterior amygdaloid area than the brain of XX embryos, withindependence of their gonadal sex. Furthermore, estradiol ordihydrotestosterone increased the expression of aromatase in cultures ofamygdaline neurons derived from XX embryos, but not in those derived from XYembryos, with independence of their gonadal sex. Sex chromosome complement wasnot involved in the regulation of the expression of other steroidogenicmolecules, such as StAR, P450scc or 5α-reductase and was not involved in the generation of sexdifferences in the expression of estrogen receptor-α and androgen receptor inaromatase-positive brain regions, which depended on gonadal sex. In conclusion,sex chromosome complement determine the expression of aromatase and theresponse of aromatase expressing neurons to gonadal hormones and both sexchromosome factors and gonadal factors regulate the expression of moleculesinvolved in the generation of brain sex differences, such as aromatase,estrogen receptor-αand androgen receptor.