Shen P, Schlinger B A, Campagnoni A T, Arnold A P
Mental Retardation Research Center, University of California, Los Angeles 90095, USA.
J Comp Neurol. 1995 Sep 11;360(1):172-84. doi: 10.1002/cne.903600113.
Neural conversion of androgen to estrogen by aromatase is an important step in the development and expression of masculine behavior in mammals and birds. In contrast to the low telencephalic levels of aromatase in adult mammals and nonsongbirds, the zebra finch telencephalon possesses high aromatase activity. This study maps, by in situ hybridization, cells that express aromatase mRNA in the adult zebra finch telencephalon, diencephalon, midbrain, and pons. High aromatase mRNA expression was observed in the caudal neostriatum, limbic archistriatum, and hypothalamus. The hippocampus, parahippocampal area, and hyperstriatum accessorium contained cells expressing moderate amounts of aromatase message. Weakly labeled cells were found in the rostral neostriatum, lobus parolfactorius, and mesencephalic reticular formation. These findings are consistent with aromatase activity measurements of zebra finch tissue and document with anatomical precision both the widespread expression of aromatase mRNA in the brain and novel sites of brain aromatase. This study identifies the caudal neostriatum as a major site of telencephalic aromatase. A previous survey (Gahr et al., 1993: J. Comp. Neurol. 327:112-122) of several avian species found that the presence of estrogen receptors in parts of the caudal neostriatum is unique to songbirds, which are the only birds to possess the elaborated telencephalic song system. Together, these findings suggest that the heightened estrogen synthesis and estrogen sensitivity of the passerine caudal neostriatum may have some functional relation with the telencephalic circuits responsible for song.
芳香化酶将雄激素转化为雌激素的神经过程是哺乳动物和鸟类雄性行为发育与表现的重要环节。与成年哺乳动物和非鸣禽端脑内芳香化酶水平较低不同，斑胸草雀的端脑具有较高的芳香化酶活性。本研究通过原位杂交技术，绘制成年斑胸草雀端脑、间脑、中脑和脑桥中表达芳香化酶mRNA的细胞分布图。在尾侧新纹状体、边缘古纹状体和下丘脑观察到高芳香化酶mRNA表达。海马体、海马旁区域和副新纹状体含有表达适量芳香化酶信息的细胞。在嘴侧新纹状体、嗅觉叶和中脑网状结构中发现标记较弱的细胞。这些发现与斑胸草雀组织的芳香化酶活性测量结果一致，精确地从解剖学角度记录了芳香化酶mRNA在脑中的广泛表达以及脑芳香化酶的新位点。本研究确定尾侧新纹状体是端脑芳香化酶的主要位点。先前对几种鸟类的调查（Gahr等人，1993年：《比较神经学杂志》327卷：112 - 122页）发现，尾侧新纹状体部分区域存在雌激素受体是鸣禽独有的特征，鸣禽是唯一拥有复杂端脑鸣唱系统的鸟类。综合这些发现表明，雀形目尾侧新纹状体中增强的雌激素合成和雌激素敏感性可能与负责鸣唱的端脑回路存在某种功能关系。
