Hutchison J B, Schumacher M, Hutchison R E
MRC Neuroendocrine Development and Behaviour Group, Institute of Animal Physiology, Babraham, Cambridge, U.K.
Brain Res Dev Brain Res. 1990 Dec 15;57(2):187-95. doi: 10.1016/0165-3806(90)90045-z.
Sex differences in the metabolism of testosterone (T) in the developing brain of quail were examined using an in vitro microassay. During each developmental stage (day before hatching, hatching and 2 days after hatching) aromatase activity was higher in hypothalamic areas than in a control neostriatal area. There was no sex difference in oestradiol-17 beta (E2) formation in the late embryonic brain or at hatching. But aromatase activity in the male preoptic-anterior hypothalamic area was 50% higher than in females by day 2. No regional differences in brain 5 beta-reductase activity were detected at any of the developmental stages sampled. There was a sex difference in production of catabolic 5 beta-reduced metabolites. Male 5 beta-reductase activity declined continuously from high embryonic levels in all areas, whereas female enzyme activity showed an increase at hatching. In contrast to plasma progesterone, levels of T were higher in the male than in the female by day 1 after hatching. We suggest that elevated circulating T in the male after hatching may account for the sexual dimorphism in brain aromatase activity.
利用体外微量分析法研究了鹌鹑发育中的大脑中睾酮（T）代谢的性别差异。在每个发育阶段（孵化前一天、孵化时和孵化后两天），下丘脑区域的芳香化酶活性高于对照新纹状体区域。在胚胎晚期大脑或孵化时，雌二醇-17β（E2）的形成没有性别差异。但到第2天时，雄性视前区-下丘脑前部区域的芳香化酶活性比雌性高50%。在任何采样的发育阶段均未检测到大脑5β-还原酶活性的区域差异。在分解代谢的5β-还原代谢物的产生上存在性别差异。雄性所有区域的5β-还原酶活性从胚胎期的高水平持续下降，而雌性酶活性在孵化时增加。与血浆孕酮不同，孵化后第1天雄性体内的T水平高于雌性。我们认为，孵化后雄性体内循环T升高可能是大脑芳香化酶活性性别二态性的原因。
