Saldanha C J, Burstein S R, Duncan K A
Department of Biology and Psychology, American University, Washington, DC, USA.
J Neuroendocrinol. 2013 Nov;25(11):1032-8. doi: 10.1111/jne.12067.
Studies on birds have long provided landmarks and touchstones in the fields of neuroendocrinology, immunology and neuroplasticity. The passerine brain is an excellent model for studying the actions of hormones, including steroids, on a diversity of behavioural endpoints. Oestrogens, for example, have profound effects on avian neuroanatomy and neurophysiology throughout life and, importantly, are synthesised at high levels within neurones of the songbird brain. More recently, aromatisation in another set of neural cells has been identified. Specifically, aromatase expression is induced in astrocytes and radial glia following disruption of the neuropil by multiple forms of perturbation. The avian brain, therefore, can be provided with high levels of oestrogens constitutively or via induction, by aromatisation in neurones and glia, respectively. In this review, we begin with the initial discovery of aromatisation by non-neuronal cells and discuss the mechanisms underlying the induction of aromatase expression in glial cells. We then focus on the emerging interactions between the neuroendocrine and neuroimmune systems with respect to brain injury. Next, we briefly review the extensive literature on the influence of glial aromatisation on neuroplasticity, and end with some recent data on sex differences in the induction of glial aromatase in the zebra finch. Throughout this review, we consider the unanswered questions and future studies that may emerge from these findings.
长期以来，对鸟类的研究为神经内分泌学、免疫学和神经可塑性领域提供了里程碑和试金石。雀形目鸟类的大脑是研究包括类固醇在内的激素对多种行为终点作用的极佳模型。例如，雌激素在鸟类的整个生命周期中对神经解剖学和神经生理学都有深远影响，重要的是，鸣禽大脑的神经元内会大量合成雌激素。最近，在另一组神经细胞中发现了芳香化作用。具体而言，在多种形式的扰动破坏神经毡后，星形胶质细胞和放射状胶质细胞中会诱导芳香化酶表达。因此，鸟类大脑可以通过神经元和胶质细胞中的芳香化作用，分别持续地或通过诱导获得高水平的雌激素。在这篇综述中，我们首先介绍非神经元细胞芳香化作用的最初发现，并讨论胶质细胞中芳香化酶表达诱导的潜在机制。然后，我们关注神经内分泌系统和神经免疫系统在脑损伤方面新出现的相互作用。接下来，我们简要回顾关于胶质细胞芳香化作用对神经可塑性影响的大量文献，并以斑胸草雀胶质细胞芳香化酶诱导中的性别差异的一些最新数据作为结尾。在这篇综述中，我们考虑了这些发现可能引发的未解决问题和未来研究方向。
