Axogenic response to 17â-estradiol in hypothalamic neurons of transgenic XY-Sry male mice

LUCCI, MARÍA SOLEDAD Y CAMBIASSO, MARÍA JULIA

Mendoza

Congreso; XXVI Reunión Científica Annual de la Sociedad de Biología de Cuyo; 2008

Sociedad de Biologia de Cuyo

Previous work from our laboratory has demonstrated that only neurons from the hypothalamus of male rats (gestational age 16 days, E16) respond with increased axonal growth to addition of 17â-estradiol (E2) to the culture medium. Transgenic XY-Sry mice are a powerful tool to study the sexual differentiation of the brain. In order to confirm an axogenic effect of E2 in this model, hypothalamic neurons from male embryos of E15 and E16 were cultured with E2 (10 and 100 nmol/L) or without E2. After 48 h in vitro, neurite outgrowth was quantified by morphometric analysis. Hypothalamic neurons from E15 embryos had less (p < 0.001) and shorter (p < 0.001) minor processes than neurons from E16, according to age. Significant differences in axonal length were found due to gestational age and hormone treatment, with a significant interaction between the two factors (p < 0.001 for all effects). At E16, hypothalamic neurons grown in cultures with 100 nmol/L E2 had longer axons than neurons grown with 10 nmol/L E2 or without E2 (p < 0.001). Neurons derived from E15 embryos showed no significant effects of E2. These preliminary data show that neuronal cultures of XY-Sry mouse embryos are a good model to study the effect of gonadal hormones and the Sry gene on E2-induced axogenesis in the developing hypothalamus at E16.