Structural organization and functional roles of electrical synapses formed by Cx36-containing gap junctions in neural systems

由连接蛋白组成的细胞间通讯通道在神经元之间形成缝隙连接，产生介导直接电神经传递的电突触。我的团队和其他人已经在大脑和脊髓的许多区域发现了由连接蛋白36（Cx36）形成的电突触。我们的长期目标之一是扩展这些突触在神经元回路中的功能作用的知识。在这里，我们的目标是获得了解电突触的神经元系统，从根本上管理重要的生理过程相关的性行为的要求。我们已经证明了大量的电突触连接运动神经元在较低水平的脊髓。这些运动神经元是独特的，因为与其他运动神经元不同，它们通过缝隙连接连接，并且它们是两性异形的，这意味着它们沿着它们的目标肌肉在男性中发育良好，而在女性中发育较差。这些运动神经元控制着骨盆底肌肉的活动，这些肌肉控制着性行为。在这些运动神经元中混杂着那些介导尿道外括约肌和肛门外括约肌收缩的神经元，这些神经元似乎也通过缝隙连接连接。与啮齿类动物一样，在人类中也发现了这些运动神经元之间的缝隙连接。在尿道生殖反射的激发过程中，模仿性活动期间的运动神经元活动，双形运动神经元和它们的靶肌肉高度同步活动。这种同步是电突触赋予的标志性特性。然而，两性异形运动神经元之间的电耦合尚未研究，也不知道这些运动神经元之间的这种耦合支配他们的不同的目标肌肉可能是组织。这种双态系统提供了一个理想的模型，其中电突触赋予神经元网络的关键特征可以与该网络所提供的生理功能相关。我们假设，电耦合是一个基本要素的双形运动神经元和那些支配括约肌，并需要协调同步运动神经元和目标肌肉活动在性行为。我们将使用解剖学和电生理学的方法在正常和缺乏Cx36的转基因小鼠，以建立这些突触在多大程度上有助于与性活动有关的生理过程。

Intercellular communication channels composed of connexin proteins form gap junctions between neurons, creating electrical synapses that mediate direct electrical neurotransmission. My group and others have found electrical synapses formed by connexin36 (Cx36) in many regions of brain and spinal cord. One of our long-term objectives is to extend knowledge of the functional roles of these synapses in neuronal circuitry. Here, we aim to acquire understanding of the requirements for electrical synapses in a neuronal system that governs fundamentally important physiological processes related to sexual behaviour. We have documented an abundance of electrical synapses connecting motoneurons at lower levels of the spinal cord. These motoneurons are unique because, unlike other motoneurons, they are linked by gap junctions and they are sexually dimorphic, meaning that they along with their target muscles are well developed in males and less so in females. These motoneurons control the activity of muscles in the pelvic floor that govern sexual behavior. Intermingled among these motoneurons are those that mediate contraction of the external urethral and external anal sphincters and that also appear to be linked by gap junctions. As in rodents, gap junctions between these motoneurons were found in humans. During elicitation of the urethrogenital reflex, which mimics motoneuronal activity during sexual activity, the dimorphic motoneurons and their target muscles are highly synchronously active. Such synchronization is a hallmark property conferred by electrical synapses. However, electrical coupling between sexually dimorphic motoneurons has not been studied, and nothing is known about how this coupling between these motoneurons innervating their different target muscles might be organized. This dimorphic system provides an ideal model in which the key features that electrical synapses confer in a neuronal network can be related to physiological functions subserved by that network. We hypothesize that electrical coupling is an essential element of dimorphic motoneurons and those innervating sphincter muscles, and is required for coordinating synchronous motoneuronal and target muscle activity during sexual behavior. We will use anatomical and electrophysiological approaches in normal and transgenic mice lacking Cx36 to establish the extent to which these synapses contribute to physiological processes related to sexual activity.