Remage-Healey L, Oyama R K, Schlinger B A
Department of Physiological Science, Laboratory for Neuroendocrinology, Brain Research Institute, University of California, Los Angeles, CA 90095, USA.
J Neuroendocrinol. 2009 Mar;21(3):191-9. doi: 10.1111/j.1365-2826.2009.01820.x. Epub 2009 Jan 15.
The enzyme aromatase, which converts androgens into oestrogens, is expressed throughout the brain in zebra finches. Aromatase is enzymatically active in both cell bodies and synaptic terminals of neurones of the songbird brain, particularly within the forebrain motor and auditory networks. Aromatisation within synaptic terminals could thus provide localised and acute modulatory oestrogens within the forebrain during singing and/or audition. In male zebra finches, we tested the hypothesis that forebrain aromatase activity is elevated during singing behaviour and/or hearing male song. The present study reports that aromatase activity is elevated in males that were singing for 30 min compared to nonsinging males, and that this elevation occurs only within the cellular compartment that contains synaptic terminals. In a separate experiment, males that heard acoustic playback of song for 30 min exhibited no differences in aromatase activity or in aromatase mRNA levels, as revealed by quantitative polymerase chain reaction analysis. Therefore, these results indicate that activation of the motor pathway for song production is linked to local elevations in synaptic aromatase activity within the forebrain of male zebra finches. Future experiments could assess whether elevated synaptic aromatase activity during song is dependent on acute regulation of the aromatase protein.
将雄激素转化为雌激素的芳香化酶在斑胸草雀的整个大脑中均有表达。芳香化酶在鸣禽大脑神经元的细胞体和突触终末均具有酶活性，尤其是在前脑运动和听觉网络中。因此，突触终末内的芳香化作用可在鸣叫和/或听觉过程中在前脑提供局部且即时的调节性雌激素。在雄性斑胸草雀中，我们测试了如下假设：在前脑的鸣叫行为和/或听到雄鸟鸣叫声期间，芳香化酶活性会升高。本研究报告称，与不鸣叫的雄性相比，鸣叫30分钟的雄性体内芳香化酶活性升高，且这种升高仅发生在含有突触终末的细胞区室中。在另一项实验中，定量聚合酶链反应分析显示，听30分钟歌曲声音回放的雄性在芳香化酶活性或芳香化酶mRNA水平上没有差异。因此，这些结果表明，鸣唱运动通路的激活与雄性斑胸草雀前脑内突触芳香化酶活性的局部升高有关。未来的实验可以评估鸣叫过程中突触芳香化酶活性的升高是否依赖于芳香化酶蛋白的急性调节。
