Department of Integrative Biology, The University of Texas at Austin, Austin, Texas, USA.
J Comp Neurol. 2021 Jul 1;529(10):2539-2557. doi: 10.1002/cne.25108. Epub 2021 Feb 12.
Because of their roles in courtship and intrasexual competition, sexual displays are often sexually dimorphic, but we know little about the mechanisms that produce such dimorphism. Among mammals, one example is the vocalization of Alston's singing mouse (Scotinomys teguina), which consists of a series of rapidly repeated, frequency-modulated notes. The rate and duration of songs is sexually dimorphic and androgen responsive. To understand the neuronal mechanisms underlying this sexual dimorphism, we map the sites of androgen sensitivity throughout the brain, focusing analysis along a pathway that spans from limbic structures to vocal motor regions. We find widespread expression of AR immunoreactivity (AR-ir) throughout limbic structures important for social behavior and vocalization, including the lateral septum, extended amygdala, preoptic area and hypothalamus. We also find extensive AR staining along previously documented vocal motor pathways, including the periaqueductal gray, parabrachial nucleus, and nucleus ambiguus, the last of which innervates intrinsic laryngeal muscles. Lastly, AR-ir is also evident in sensory areas such as the medial geniculate, inferior, and superior colliculi. A quantitative analysis revealed that males exhibited more AR-ir than females, a pattern that was most pronounced in the hypothalamus. Despite the elaboration of vocalization in singing mice, comparison with prior literature suggests that the broad pattern of AR-ir may be conserved across a wide range of rodents. Together these data identify brain nuclei well positioned to shape the sexually dimorphic vocalization of S. teguina and suggest that such androgen modulation of vocalization is evolutionary conserved among rodents.
由于在求偶和种内竞争中的作用，性展示通常具有性别二态性，但我们对产生这种二态性的机制知之甚少。在哺乳动物中，一个例子是 Alston 的鸣鼠（Scotinomys teguina）的发声，它由一系列快速重复、频率调制的音符组成。歌曲的速率和持续时间具有性别二态性，并且对雄激素有反应。为了了解这种性别二态性的神经机制，我们绘制了整个大脑中雄激素敏感性的部位，重点分析了一条从边缘结构到发声运动区域的通路。我们发现，广泛表达 AR 免疫反应性（AR-ir），遍及与社会行为和发声有关的边缘结构，包括外侧隔核、扩展杏仁核、视前区和下丘脑。我们还沿着先前记录的发声运动通路发现了广泛的 AR 染色，包括导水管周围灰质、臂旁核和疑核，后者支配内在的喉肌。最后，AR-ir 也可见于感觉区域，如内侧膝状体、下丘和上丘。定量分析显示，雄性的 AR-ir 比雌性多，这种模式在下丘脑中最为明显。尽管鸣鼠的发声得到了精细的发展，但与先前的文献相比，AR-ir 的广泛模式可能在广泛的啮齿动物中得到了保守。这些数据共同确定了大脑核，这些核对于塑造 S. teguina 的性别二态性发声具有重要作用，并表明这种雄激素对发声的调节在啮齿动物中是进化保守的。
