Hormones and sex differences in the musk shrew

描述（由申请人提供）：类固醇激素对包括人类在内的许多物种的大脑和行为的许多观察到的性别差异负责。雌性亚洲麝香鼩（Suncus murinus）是一种食虫动物，与大多数其他哺乳动物不同的是：1)雌性麝香鼩没有行为发情周期，2)卵巢持续释放睾丸激素，而不是雌激素或黄体酮。我们发现，麝香鼩的性分化更接近灵长类动物的模式，而不是更常见的动物，如大鼠和小鼠。我们建议研究性别差异和激素控制在该物种的一些两性二态行为的发展和表现，包括交配行为和空间学习。我们将通过用睾酮及其主要代谢物治疗雌性新生儿来研究发育激素在性别分化中的作用，然后在成年期检查两性二态行为和相关的大脑结构。我们希望在一个很少被研究的哺乳动物领域增加基础研究，同时为我们的小型女子文理学院的学生提供宝贵的研究经验，以提高他们的实验室技能，并为研究生课程和研究相关职业的成功提供必要的培训。（与公共卫生相关）在性行为的调节方面，麝香鼩不同于一般研究的啮齿动物，但与灵长类动物（包括人类）有某些相似之处：1)雌性在特定的发情期以外的时间交配；2)发育性睾酮不需要转化为雌激素来塑造男性典型的性行为；3)性趣在性腺成熟之前产生，可能是受肾上腺雄激素的影响。由于灵长类动物的基础研究既昂贵又耗时，而且往往不切实际，我们建议在一种比大鼠和小鼠更接近人类的物种中开发一种替代的小型动物模型。我们相信，性别分化的动物模型将有助于理解性腺激素如何塑造发育中的人类大脑，并在以后的生活中影响可观察到的性别差异。

DESCRIPTION (provided by applicant): Steroid hormones are responsible for many observed sex differences in brain and behavior in a variety of species, including humans. The female Asian musk shrew (Suncus murinus) is an insectivore that differs from most other mammals in its 1) lack of behavioral estrus cycle and 2) continuous testosterone release by the ovaries, rather than estrogen or progesterone. We have found that aspects of musk shrew sexual differentiation more closely resemble the pattern found in primates than that in more commonly studied animals like rats and mice. We propose to examine sex differences and hormonal control of the development and display of several sexually dimorphic behaviors in this species, including copulatory behaviors and spatial learning. We will investigate the role of developmental hormones in sexual differentiation by treating females neonatally with testosterone and its major metabolites, then examining sexually dimorphic behaviors and related brain structures in adulthood. We hope to add to the body of basic research in a rarely-studied mammalian order while at the same time provide students in our small women's liberal arts college with a valuable research experience that will enhance their laboratory skills and provide training necessary for success in graduate programs and research-related careers. (RELEVANCE TO PUBLIC HEALTH) In the regulation of sexual behavior, the musk shrew differs from commonly studied rodents but shares certain similarities with primates, including humans: 1) females mate at times other than a distinct estrus period; 2) developmental testosterone does not require conversion to estrogen to shape male-typical sexual behavior; and 3) sexual interest develops prior to gonadal maturity, probably under the influence of adrenal androgens. Since basic research in primates is expensive, time-consuming and often otherwise impractical, we propose to develop an alternate small-animal model in a species that may more closely resemble humans than do rats and mice. We believe that an animal model for sexual differentiation will be useful to understanding how gonadal hormones shape the developing human brain and influence observable sex differences in later life.