Wade J, Schlinger B A, Arnold A P
Department of Psychology, University of California, Los Angeles, USA.
J Neurobiol. 1995 Jun;27(2):240-51. doi: 10.1002/neu.480270210.
Estrogen treatment of hatchling female zebra finches causes the masculine development of singing behavior and of the telencephalic brain regions involved in the control of song. However, early estrogen treatment of males also blocks masculine development of copulatory behavior, presumably controlled by diencephalic regions. In an effort to determine whether the differences in estrogen action are related to sex and regional differences in androgen metabolism (estrogen synthesis or androgen inactivation), we measured aromatase and 5 beta-reductase activity in dissociated-cell cultures made separately from the telencephalon, diencephalon, and also cerebellum of hatchling zebra finches under a variety of conditions. Cultures from all three brain regions express high levels of aromatase and 5 beta-reductase activity. Comparisons between telencephalic and diencephalic cultures of the activity and kinetics of aromatase suggest that the telencephalic cultures convert androgen to estrogen more efficiently than diencephalic cultures, which might be important in the differential action of estrogen in the two brain regions. However, the activity of neither aromatase nor 5 beta-reductase was significantly different between the sexes in either telencephalic or diencephalic cultures. Thus, comparisons between the sexes do not support the idea that differences in posthatching aromatase or 5 beta-reductase activity account for the pattern of sexual differentiation of the song and copulatory systems.
对刚孵化出的雌性斑胸草雀进行雌激素处理，会导致其鸣叫行为以及参与鸣叫控制的端脑脑区出现雄性化发育。然而，对雄性斑胸草雀进行早期雌激素处理也会阻碍交配行为的雄性化发育，推测这一行为受间脑区域控制。为了确定雌激素作用的差异是否与雄激素代谢（雌激素合成或雄激素失活）的性别差异和区域差异有关，我们在多种条件下，分别从刚孵化出的斑胸草雀的端脑、间脑以及小脑制备的解离细胞培养物中测量了芳香化酶和5β-还原酶的活性。来自所有三个脑区的培养物都表现出高水平的芳香化酶和5β-还原酶活性。对端脑和间脑培养物中芳香化酶的活性和动力学进行比较表明，端脑培养物将雄激素转化为雌激素的效率比间脑培养物更高，这可能在雌激素在两个脑区的差异作用中具有重要意义。然而，在端脑或间脑培养物中，芳香化酶和5β-还原酶的活性在两性之间均无显著差异。因此，两性之间的比较并不支持这样一种观点，即孵化后芳香化酶或5β-还原酶活性的差异解释了鸣叫和交配系统的性别分化模式。
