Plasma sex steroids and tissue aromatization in hatchling zebra finches: implications for the sexual differentiation of singing behavior.
Plasma sex steroids and tissue aromatization in hatchling zebra finches: implications for the sexual differentiation of singing behavior.
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DOI：
10.1210/endo.130.1.1727704
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发表时间：
1992
期刊：
影响因子：
4.8
通讯作者：
B. Schlinger;A. Arnold
中科院分区：
文献类型：
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作者：
B. Schlinger;A. Arnold
性激素调节大脑发育的最好例子之一是在鸣禽身上发现的。在斑胸草雀中，只有雄性才唱歌，因为控制歌声的神经回路存在显著的性别差异。由于雌激素（E2）治疗的发展中的女性发展男性歌曲系统，E2被认为是正常的雄性化激素。然而，关于E2在男性发育中的作用的问题仍然存在，因为使歌曲男性化的E2治疗可以使其他性行为去男性化，并且存在相互矛盾的证据表明，在发育中的男性中存在高水平的循环E2。在斑胸草雀孵化后的第一个13天，我们重新测量了血浆类固醇。E2循环水平较低，循环E2、雌酮、睾酮、雄烯二酮或双氢睾酮无性别差异。我们还测量了芳香化酶活性[（3H）雄烯二酮转化为[3H]雌酮和[3H]E2）在性腺，肾上腺，脑和其他组织的孵化。芳香化酶在卵巢中含量丰富，但在雄性的睾丸、肾上腺或其他非神经组织中未明确检测到。芳香化酶也被发现在间脑和大量的端脑，但未检测到性别差异在整个大脑或端脑的细胞亚组分。由于卵巢类固醇合成是高的，它可能参与了雌性斑胸草雀的分化，在nonpasserine鸟类。相比之下，歌唱男性化所必需的功能性雌激素很可能来自大脑，由肾上腺提供底物。为什么女性的歌声系统没有男性化，仍然是一个谜，因为女性拥有高水平的芳香化雄激素和端脑芳香化酶。
One of the best examples for sex hormone regulation of brain development is found in songbirds. In zebra finches, only males sing because of striking sex differences in the neural circuitry that controls songs. Because developing females treated with estradiol (E2) develop a masculine song system, E2 is considered the normal masculinizing hormone. However, questions about the role of E2 in male development persist, because E2 treatments that masculinize song can demasculinize other sexual behaviors, and there exists contradictory evidence for high levels of circulating E2 in developing males. We remeasured plasma steriods in zebra finches during the first 13 days after hatching. E2 circulated at low levels, and there were no sex differences in circulating E2, estrone, testosterone, androstenedione, or dihydrotestosterone. We also measured aromatase activity [( 3H]androstenedione conversion to [3H]estrone and [3H]E2) in gonad, adrenal, brain, and other tissues of hatchlings. Aromatase was abundant in ovary, but was not definitively detected in testes, adrenals, or other nonneural tissues of males. Aromatase was also found in diencephalon and in high amounts in telencephalon, but sex differences were not detected in whole brain or cellular subfractions of telencephalon. Because ovarian steroidogenesis is high, it may be involved in differentiation of the female zebra finch, as in nonpasserine birds. By contrast, the functional estrogen necessary for masculinization of song is most likely derived from brain, supplied with substrate from the adrenals. The puzzle remains why the song system is not masculinized in females, who possess high levels of aromatizable androgens and telencephalic aromatase.