A novel spinal circuit involved in locomotion

一种参与运动的新型脊髓回路

• 批准号: 8511482
• 负责人: George Z Mentis
• 金额: $ 24万
• 依托单位: COLUMBIA UNIVERSITY HEALTH SCIENCES
• 依托单位国家: 美国
• 财政年份: 2013
• 资助国家: 美国
• 起止时间: 2013-02-15 至 2015-01-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/8511482
• 关键词: Acetylcholine; Address; Amplifiers; Aspartate; Axon; Back; Behavior; Biological Assay; Candidate Disease Gene; Cell Nucleus; Cerebellum; Cholinergic Receptors; Complex; Exhibits; Feedback; Gene Expression Profiling; Generations; Genes; Glutamates; Goals; Immunohistochemistry; In Situ Hybridization; In Vitro; Interneurons; Label; Limb structure; Locomotion; Mediating; Methods; Microarray Analysis; Molecular; Motor; Motor Activity; Motor Neurons; Motor output; Movement; Mus; Muscle; Neonatal; Neurons; Neurosciences; Neurotransmitters; Output; Pattern; Peripheral; Physiological; Physiology; Play; Preparation; Relative (related person); Renshaw Cell; Research Design; Research Project Grants; Role; Spinal; Spinal Cord; Spinocerebellar Tracts; Synapses; Techniques; Testing; Tissue-Specific Gene Expression; Tracer; Validation; base; candidate marker; central pattern generator; design; excitatory neuron; extracellular; laser capture microdissection; molecular marker; novel; optical imaging; postnatal; public health relevance; research study; response; selective expression

DESCRIPTION (provided by applicant): A major goal of modern Neuroscience is to understand the neuronal basis of behavior. Locomotion is a behavior generated in the spinal cord by complex neuronal circuits. It is defined as precise, coordinated and alternating activity between opposing limbs as well as between antagonistic muscles of the same limb. Furthermore, locomotor behavior is attractive for experimental study because it can be easily accessed, defined, and quantified. A network of interneurons, known as the central pattern generator (CPG), is thought to be responsible for the genesis of rhythmic activity. CPG neurons activate motor neurons which in turn activate peripheral muscles resulting in movement. Motor neurons also possess axon collaterals which target exclusively a class of inhibitory interneurons, known as Renshaw cells. Our recent studies have challenged the traditional idea that motor neurons are simply the motor output from the spinal cord. Stimulation of motor neuron axons in neonatal mice can trigger locomotor activity in the presence of cholinergic receptor antagonists. This suggests that acetylcholine released by motor neuron axon collaterals is not required for rhythmogenesis. Furthermore, we discovered that neonatal motor neurons release a second fast excitatory neurotransmitter from their axon collaterals (glutamate or aspartate) in addition to acetylcholine. The mechanisms of how stimulation of motor axons can trigger locomotor-like activity in neonatal spinal cords are not understood. The identification of neurons and their connectivity that participate in the locomotor CPG is critically needed for the elucidation of mechanisms involved in locomotor activity and would therefore represent a fundamental advance in the field. In this proposal, we provide some preliminary evidence that a novel class of excitatory interneurons is a critical component in a ventral spinal cord circuit, putatively connected to lumbar motor neurons and it may be involved in the locomotor central pattern generator. We have designed a set of experiments to test our main hypothesis, that motor neurons play an active role in the generation of locomotor activity. In Aim 1, we will attempt to identify the neuronal targets of this novel type of interneuron using physiological and morphological assays. In addition, we will investigate the participation of these interneurons in locomotor-like behavior using modern optophysiological methods employing the in vitro spinal cord preparation. Optophysiological approaches combine optical imaging with electrophysiological techniques. In Aim 2, we will perform laser capture microdissection from these interneurons compared to motor neurons using a differential gene microarray analysis. Validation of gene(s) expressed solely in these interneurons will be performed by in situ hybridization techniques. In summary, this two-year research project describes a comprehensive set of experiments that have the potential to identify a novel class of excitatory interneurons as a key neuronal player in the rhythmogenesis of locomotor activity.

描述（由申请人提供）：现代神经科学的一个主要目标是了解行为的神经元基础。运动是由复杂的神经回路在脊髓中产生的行为。它被定义为相对肢体之间以及同一肢体的拮抗肌之间的精确，协调和交替活动。此外，运动行为是有吸引力的实验研究，因为它可以很容易地访问，定义和量化。被称为中央模式发生器（CPG）的中间神经元网络被认为负责节律活动的发生。CPG神经元激活运动神经元，运动神经元又激活外周肌肉，导致运动。运动神经元还具有轴突侧支，其专门针对一类抑制性中间神经元，称为Renshaw细胞。我们最近的研究挑战了传统的观点，即运动神经元只是脊髓的运动输出。在胆碱能受体拮抗剂的存在下，刺激新生小鼠的运动神经元轴突可以触发运动活动。这表明运动神经元轴突侧支释放的乙酰胆碱不是节律发生所必需的。此外，我们发现，新生的运动神经元释放第二个快速兴奋性神经递质从他们的轴突侧支（谷氨酸或天冬氨酸）除了乙酰胆碱。运动轴突的刺激如何触发新生儿脊髓中的运动样活动的机制尚不清楚。识别 参与运动CPG的神经元及其连接对于阐明参与运动活动的机制是至关重要的，因此将代表该领域的根本性进展。在这个建议中，我们提供了一些初步的证据，一类新的兴奋性中间神经元是腹侧脊髓回路中的一个关键组成部分，pueries连接到腰部运动神经元，它可能参与运动中枢模式发生器。我们设计了一组实验来验证我们的主要假设，即运动神经元在自发活动的产生中起着积极的作用。在目标1中，我们将尝试使用生理学和形态学分析来识别这种新型中间神经元的神经元靶点。此外，我们将研究这些中间神经元参与运动样行为，使用现代光生理学方法采用体外脊髓制备。光学生理学方法将光学成像与电生理学技术联合收割机结合。在目标2中，我们将使用差异基因微阵列分析对这些中间神经元和运动神经元进行激光捕获显微切割。将通过原位杂交技术验证仅在这些中间神经元中表达的基因。总之，这个为期两年的研究项目描述了一套全面的实验，有可能确定一类新的兴奋性中间神经元作为运动活动的节律发生中的关键神经元。