Metaplasticity and Recovery After Spinal Cord Injury: Cellular Mechanisms

脊髓损伤后的再生和恢复：细胞机制

• 批准号: 8230529
• 负责人: ADAM R FERGUSON
• 金额: $ 32.56万
• 依托单位: UNIVERSITY OF CALIFORNIA, SAN FRANCISCO
• 依托单位国家: 美国
• 财政年份: 2010
• 资助国家: 美国
• 起止时间: 2010-03-01 至 2015-02-28
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/8230529
• 关键词: AMPA Receptors; Agonist; Biochemical; Brain-Derived Neurotrophic Factor; Cell Culture Techniques; Cell Death; Cell Fractionation; Cell membrane; Communication; Confocal Microscopy; Data; Dental crowns; Dose; Enzyme-Linked Immunosorbent Assay; Fiber; Fractionation; Functional disorder; Future; Glutamate Receptor; Glutamates; Goals; Hindlimb; Hippocampus (Brain); Immunofluorescence Immunologic; Impairment; In Situ Hybridization; Injury; Intractable Pain; Lead; Learning; Leg; Link; Literature; Locomotor Recovery; Mediating; Messenger RNA; Methods; Monitor; Natural regeneration; Neurons; Neurorehabilitation; Nociception; Outcome; Pain; Patients; Peripheral; Play; Positioning Attribute; Preparation; Proteins; Rattus; Recovery; Recovery of Function; Research; Reverse Transcriptase Polymerase Chain Reaction; Role; Sensory; Shapes; Shock; Spinal; Spinal Cord; Spinal Cord Contusions; Spinal Cord transection injury; Spinal cord injury; Stimulus; Synaptic Membranes; Synaptic plasticity; Syndrome; TNF gene; Tactile; Testing; Therapeutic; Thoracic spinal cord structure; Time; Training; Tumor Necrosis Factor-alpha; Urination; Western Blotting; Work; behavioral pharmacology; cytokine; excitotoxicity; improved; in vivo; inhibitor/antagonist; motor control; nerve supply; neural patterning; neuronal excitability; new therapeutic target; novel; prevent; public health relevance; relating to nervous system; research study; response; therapeutic target; trafficking

DESCRIPTION (provided by applicant): Prior research has shown that neurons within the spinal cord are sensitive to response-outcome (instrumental) relationships. Rats with complete spinal cord transections can learn to maintain the hindlimb in a flexed position if leg shock is delivered when the leg is extended (response- contingent shock). Using this simple preparation, we have shown that stimulation alters the capacity for spinal learning in a bidirectional manner. Training with response-contingent shock promotes later spinal learning. Conversely, nociceptive stimulation that is independent of leg position (uncontrollable shock or peripheral paw injury) inhibits future spinal learning and impairs locomotor recovery after contusive spinal cord injury (SCI). Prior work has found that these impairments in spinal learning depend on a maladaptive form of glutamate-mediated plasticity that impairs future use-dependent plasticity in the spinal cord. The cellular mechanisms regulating this plasticity of plasticity ("metaplasticity") are not well-understood. Our hypothesis is that the cytokine tumor necrosis factor a (TNFa) within the spinal cord plays a critical mechanistic role in spinal learning impairments after uncontrollable stimulation. TNFa is released in elevated levels after SCI or nociceptive stimulation. TNFa has recently been found to alter synaptic plasticity within the injured spinal cord by increasing trafficking of the glutamate AMPA receptor (AMPAR) to the plasma membrane of spinal neurons. Preliminary data suggest that TNFa-induced AMPAR trafficking may contribute to spinal learning impairments after SCI. Intrathecal delivery of an AMPAR agonist or TNFa impairs spinal learning. Conversely a TNFa inhibitor promotes spinal learning. Aim 1 establishes the dose-response and temporal features of these TNFa-mediated effects. Aim 2 evaluates TNFa mRNA and protein levels in the spinal cord after uncontrollable stimulation using qRT-PCR, ELISA, in situ hybridization and immunofluorescence. Aim 3 examines TNF-induced trafficking of AMPARs to the plasma membrane of spinal neurons after uncontrollable stimulation by biochemical and confocal microscopy methods. Aim 4 tests the therapeutic potential of a TNFa1 inhibitor for promoting use-dependent plasticity and recovery of function after contusive SCI. Our long-term goal is to unravel the mechanisms that regulate adaptive spinal plasticity, allowing patients to re-establish essential functions, while limiting the maladaptive plasticity that can lead to spasticity or intractable pain. By defining key mechanisms that disable spinal cord learning and recovery of function, we hope to provide novel therapeutic targets that promote spinal cord learning and neurorehabilitation after SCI. PUBLIC HEALTH RELEVANCE: Project Narrative/Public Health Relevance Statement Spinal cord Injury (SCI) produces a devastating syndrome that is characterized by loss of motor control and mobility, as well as sensory dysfunction and pain. The proposed project explores cellular mechanisms that regulate a form of spinal cord learning that is thought to contribute to recovery of function after SCI. These studies may provide a novel target for improving recovery after SCI.

描述（由申请人提供）：先前的研究表明，脊髓内的神经元对反应结果（工具）关系敏感。如果腿部伸展腿部，则具有完整脊髓过渡的大鼠可以学会将后肢保持弯曲的位置（反应反应冲击）。使用这种简单的准备，我们表明刺激以双向方式改变了脊柱学习的能力。用反应式冲击训练会促进后来的脊柱学习。相反，与腿部位置无关的伤害性刺激（不可控制的冲击或外周爪损伤）抑制了未来的脊柱学习，并损害脊髓损伤（SCI）后的运动恢复。先前的工作发现，脊柱学习中的这些损害取决于谷氨酸介导的可塑性的不良适应性形式，从而损害了脊髓中未来使用依赖性的可塑性。调节可塑性可塑性的细胞机制（“化生性”）并不理解。 我们的假设是，脊髓中的细胞因子肿瘤坏死因子A（TNFA）在无法控制的刺激后在脊柱学习障碍中起关键的机械作用。 SCI或伤害感受刺激后，TNFA以升高水平释放。最近，发现TNFA通过将谷氨酸AMPA受体（AMPAR）的运输增加到脊髓神经元的质膜来改变受伤的脊髓内的突触可塑性。 初步数据表明，TNFA诱导的AMPAR运输可能会导致SCI后的脊柱学习障碍。 AMPAR激动剂或TNFA的鞘内递送会损害脊柱学习。相反，TNFA抑制剂促进了脊柱学习。 AIM 1建立了这些TNFA介导的效果的剂量反应和时间特征。 AIM 2使用QRT-PCR，ELISA，原位杂交和免疫荧光评估脊髓中的TNFA mRNA和蛋白水平。 AIM 3检查了通过生化和共聚焦显微镜方法无法控制的刺激后TNF诱导的AMPAR对脊柱神经元质膜的运输。 AIM 4测试TNFA1抑制剂在促进使用依赖性可塑性和功能恢复后的治疗潜力。 我们的长期目标是阐明调节适应性脊柱可塑性的机制，使患者能够重新建立基本功能，同时限制可能导致痉挛或顽固性疼痛的不良适应性可塑性。通过定义禁用脊髓学习和功能恢复的关键机制，我们希望提供新型的治疗靶标，以促进SCI后促进脊髓学习和神经康复。 公共卫生相关性：项目叙事/公共卫生相关性声明脊髓损伤（SCI）产生了一种毁灭性综合征，其特征是运动控制和移动性丧失以及感觉功能障碍和疼痛。拟议的项目探讨了调节脊髓学习形式的细胞机制，该机制被认为有助于SCI后功能的恢复。这些研究可能为改善SCI后的恢复提供了新的目标。

项目成果

Metaplasticity and behavior: how training and inflammation affect plastic potential within the spinal cord and recovery after injury.

• DOI: 10.3389/fncir.2014.00100
• 发表时间: 2014
• 期刊: Frontiers in neural circuits
• 影响因子: 3.5
• 作者: Grau JW;Huie JR;Lee KH;Hoy KC;Huang YJ;Turtle JD;Strain MM;Baumbauer KM;Miranda RM;Hook MA;Ferguson AR;Garraway SM
• 通讯作者: Garraway SM