Rosenfeld Cheryl S
Bond Life Sciences Center, University of Missouri, Columbia, MO, United States.
Biomedical Sciences, University of Missouri, Columbia, MO, United States.
Front Neurosci. 2017 Nov 16;11:632. doi: 10.3389/fnins.2017.00632. eCollection 2017.
Brain sexual differentiation is orchestrated by precise coordination of sex steroid hormones. In some species, programming of select male brain regions is dependent upon aromatization of testosterone to estrogen. In mammals, these hormones surge during the organizational and activational periods that occur during perinatal development and adulthood, respectively. In various fish and reptiles, incubation temperature during a critical embryonic period results in male or female sexual differentiation, but this can be overridden in males by early exposure to estrogenic chemicals. Testes development in mammals requires a Y chromosome and testis determining gene (in humans) (all other therian mammals), although there are notable exceptions. Two species of spiny rats: Amami spiny rat () and Tokunoshima spiny rat () and two species of mole voles (), lack a Y chromosome/ and possess an XO chromosome system in both sexes. Such rodent species, prototherians (monotremes, who also lack ), and fish and reptile species that demonstrate temperature sex determination (TSD) seemingly call into question the requirement of for brain sexual differentiation. This review will consider brain regions expressing / in humans and rodents, respectively, and potential roles of / in the brain will be discussed. The evidence from various taxa disputing the requirement of for brain sexual differentiation in mammals (therians and prototherians) and certain fish and reptilian species will be examined. A comparative approach to address this question may elucidate other genes, pathways, and epigenetic modifications stimulating brain sexual differentiation in vertebrate species, including humans.
脑性分化是由性类固醇激素的精确协调所调控的。在某些物种中，特定雄性脑区的编程依赖于睾酮向雌激素的芳香化作用。在哺乳动物中，这些激素分别在围产期发育和成年期出现的组织期和激活期激增。在各种鱼类和爬行动物中，关键胚胎期的孵化温度会导致雄性或雌性的性分化，但早期接触雌激素类化学物质可使雄性的这种分化被逆转。哺乳动物的睾丸发育需要Y染色体和睾丸决定基因（人类）（所有其他有胎盘哺乳动物），不过也有明显的例外情况。两种刺鼠：奄美刺鼠（）和德之岛刺鼠（）以及两种麝鼠（），缺乏Y染色体/且两性均拥有XO染色体系统。这类啮齿动物物种、原兽亚纲动物（单孔目动物，它们也缺乏）以及表现出温度依赖型性别决定（TSD）的鱼类和爬行动物物种，似乎对Y染色体在脑性分化中的必要性提出了质疑。本综述将分别考虑人类和啮齿动物中表达/的脑区，并讨论/在脑中的潜在作用。将审视来自各种分类群的证据，这些证据对哺乳动物（有胎盘类和原兽亚纲）以及某些鱼类和爬行动物物种中Y染色体在脑性分化中的必要性提出了争议。采用比较方法来解决这个问题可能会阐明其他刺激脊椎动物物种（包括人类）脑性分化的基因、信号通路和表观遗传修饰。
