Gorski R A
J Anim Sci. 1985;61 Suppl 3:38-61. doi: 10.1093/ansci/61.supplement_3.38.
This discussion reviews, partially from the historical perspective of the author, the development and evolution of the concept of the sexual differentiation of the brain, a process that has profound implications for reproductive biology, animal behavior and developmental neurobiology. Although there are numerous sex differences in brain function, the mammalian brain appears to be fundamentally female. Characteristics of brain function typical of the male sex are imposed on the developing brain by the action of testicular hormones. In fact, estradiol produced intraneuronally by the aromatization of testicular testosterone, appears to be the hormonal molecule responsible for the masculine differentiation of the brain. Much of the research in this area has been descriptive in nature, and studies of the possible mechanisms of hormone action have been limited to very general approaches because of the complexities of the process and the lack of specific model systems. Recently, marked structural correlates of sexual differentiation have been identified. The sexually dimorphic nucleus of the preoptic area (SDN-POA), for example, is now viewed as a morphological signature of the action of gonadal hormones on the developing brain and has become a model system to investigate the fundamental mechanism(s) by which hormones act to determine the structure and functional capacity of the brain. Although possible effects of estradiol on neurogenesis and(or) neuronal migration cannot be excluded, it currently appears that one mechanism of the sexual differentiation of the brain is the hormonal promotion of neuronal survival during a developmental phase of neuronal death. The discovery of the SDN-POA in the rat emphasizes the value of the comparative approach to sexual differentiation. It is likely that other animal species may prove to be species of choice for future investigations of components of the complex process of the sexual differentiation of the brain.
本文部分从作者的历史视角回顾了脑性别分化概念的发展与演变，这一过程对生殖生物学、动物行为学和发育神经生物学具有深远影响。尽管脑功能存在众多性别差异，但哺乳动物的脑在本质上似乎是雌性的。雄性典型的脑功能特征是由睾丸激素作用于发育中的脑而形成的。事实上，睾丸睾酮经芳香化作用在神经元内产生的雌二醇，似乎是负责脑雄性分化的激素分子。该领域的许多研究本质上是描述性的，由于过程复杂且缺乏特定模型系统，对激素作用可能机制的研究一直局限于非常笼统的方法。最近，已确定了性别分化的明显结构关联。例如，视前区性二态核（SDN-POA）现在被视为性腺激素对发育中脑作用的形态学标志，并已成为研究激素决定脑结构和功能能力基本机制的模型系统。尽管不能排除雌二醇对神经发生和（或）神经元迁移的可能影响，但目前看来，脑性别分化的一种机制是在神经元死亡的发育阶段，激素促进神经元存活。大鼠中SDN-POA的发现强调了比较方法在性别分化研究中的价值。其他动物物种很可能会被证明是未来研究脑性别分化这一复杂过程组成部分的首选物种。
