Role of ryanodine receptor dysfunction after spinal cord injury

兰尼碱受体功能障碍在脊髓损伤后的作用

• 批准号: 9751868
• 负责人: Helen M Bramlett
• 金额: --
• 依托单位: JAMES J PETERS VA MEDICAL CENTER
• 依托单位国家: 美国
• 财政年份: 2017
• 资助国家: 美国
• 起止时间: 2017-10-01 至 2021-09-30
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/9751868
• 关键词: Affect; Aging; American; Animal Model; Area; Atrophic; Behavioral; Binding; Calcium; Collaborations; Contusions; Coupling; Data; Deterioration; Disseminated Malignant Neoplasm; Dissociation; Drug usage; Fatigue; Fiber; Force of Gravity; Functional disorder; Gait; Hand; Hindlimb; Impairment; Individual; Injury; Intervention; Knock-out; Knowledge; Lead; Lesion; Link; Locomotion; Longevity; Modeling; Motor; Motor Neurons; Mus; Muscle; Muscle Contraction; Muscle Weakness; Muscle function; NADH oxidase; Outcome; Oxides; Paralysed; Pharmaceutical Preparations; Pharmacologic Substance; Pharmacology; Physiological; Production; Quality of Care; Quality of life; Reactive Oxygen Species; Recovery of Function; Rehabilitation therapy; Research Personnel; Resistance; Role; Ryanodine Receptor Calcium Release Channel; Ryanodine Receptors; Sarcoplasmic Reticulum; Skeletal Muscle; Source; Spinal Cord; Spinal Cord Contusions; Spinal Cord transection injury; Spinal cord injury; Testing; Thoracic spinal cord structure; Time; Ursidae Family; Veterans; Weight; Work; arm; disability; effective therapy; experience; experimental study; gait examination; improved; improved functioning; inhibitor/antagonist; muscle strength; neuromuscular function; novel; oxidation; prevent; response; small molecule; treatment effect

Muscles paralyzed by spinal cord injury (SCI) atrophy extensively, are weaker, fatigue more quickly and generate lower specific tension (force produced per unit of cross-sectional area), such that they generate less force in response to maximal motor neuron activation. For individuals with motor-incomplete lesions, interventions that improve specific force and/or fatigue resistance would be obvious opportunities to improve function. A newly recognized cause of impaired specific force production is oxidation/nitrosylation of ryanodine receptors (RyR) which results in dissociation of calstabin and spontaneous opening of RyR thereby impairing RyR gating; the ultimate physiological effect of RyR dysfunction is diminished force of muscle contraction and lower muscle endurance. Small molecules such as S107 bind oxidized/nitrosylated RyR and improve specific force by as much as 50%. Our preliminary data demonstrates extensive oxidation/nitrosylation of RyR in muscle after SCI thus implicating RyR dysfunction in reduced specific force production and endurance of paralyzed muscle after SCI. These changes in RyR are associated with increased expression of NADH oxidase 4 (Nox4) which is a potent source of reactive oxygen species (ROS) that has been linked to RyR. A direct link between Nox4 and oxidation/nitrosylation of RyR is supported by findings that binding of Nox4 to RyR is also increased in muscle after SCI. The overarching objectives of this application are to test the possibility that administration of S107 or a Nox4 inhibitor after SCI will improve skeletal muscle specific tension and endurance, and hence function, and to investigate the role of Nox4 in oxidation/nitrosylation of RyR in skeletal muscle after SCI. Aim 1. To determine the role of elevated Nox4 expression in the oxidation/nitrosylation of RyR in muscle after spinal cord transection. Hypothesis: oxidation/nitrosylation of RyR after SCI results from increased expression and activity of Nox4. Approach. Aim 1A. We will compare SCI and sham-operated groups over time after a spinal cord transection at various times between 1 and 56 days after SCI. We will examine the temporal relationships between oxidation/nitrosylation of RyR and dissociation of calstabin from RyR with changes in Nox4 expression. Aim 1B: Effects of a conditional knockout of Nox4 in skeletal muscle on muscle strength, specific force, fatigue, RyR oxidation after SCI will be determined. Aim 1C: We will compare muscle force production, specific force, fatigue, RyR oxidation/nitrosylation and binding of RyR to calstabin between spinal cord transected mice treated with a Nox4 inhibitor or vehicle. Aim 2) To test the effects of S107 on muscle force production and RyR-calstabin binding interactions after spinal cord transection. Hypothesis: administration of S107 will improve muscle specific force and endurance and increase calstabin binding to RyR but will not alter RyR oxidation/nitrosylation. Approach: We will compare muscle specific force, endurance, binding of calstabin to RyR, and RyR oxidation/nitrosylation between SCI groups administered S107 or vehicle. Aim 3. To A) determine whether S107 or a Nox4 inhibitor improves functional recovery after a contusion SCI. Hypothesis: S107 or a Nox4 inhibitor improves functional recovery in a graded contusion model of mid-thoracic SCI in mice. Approach: Following a mild, moderate or severe contusion spinal cord injury, mice will be treated with the most effective drug (either S107 or GKT137831) from Aims 1 and 2 or vehicle. Effects of the treatment on locomotor function and gait will be determined. Expected Outcomes and Benefits to Veterans. Knowledge gained from such studies may result in new pharmacologic or rehabilitation treatments to improve function after SCI.

脊髓损伤（SCI）瘫痪的肌肉广泛萎缩，更弱，疲劳更快， 产生较低的比张力（每单位横截面积产生的力），使得它们产生 对最大运动神经元激活的响应力较小。对于运动功能不全的患者， 改善比力和/或抗疲劳性的干预将是明显的机会， 功能一种新认识到的比力产生受损的原因是氧化/亚硝基化。 兰尼碱受体（RyR），其导致钙稳定蛋白的解离和RyR的自发开放 从而损害RyR门控; RyR功能障碍的最终生理效应是降低了 肌肉收缩和肌肉耐力降低。小分子如S107结合氧化/亚硝基化 RyR和提高比力高达50%。我们的初步数据显示， 脊髓损伤后肌肉中RyR的氧化/亚硝基化，从而暗示RyR功能障碍， 脊髓损伤后瘫痪肌肉的产生和耐力。RyR的这些变化与 NADH氧化酶4（Nox 4）的表达增加，这是活性氧的有效来源 (ROS)与RyR有关联Nox 4和RyR的氧化/亚硝基化之间的直接联系是 这一结果得到了脊髓损伤后肌肉中Nox 4与RyR结合也增加的研究结果的支持。总体 本申请的目的是测试S107或Nox 4抑制剂的给药后 脊髓损伤将改善骨骼肌的特异性张力和耐力，从而改善其功能，并研究脊髓损伤对骨骼肌功能的影响。 Nox 4在脊髓损伤后骨骼肌RyR氧化/亚硝基化中的作用 目标1。为了确定Nox 4表达升高在RyR氧化/亚硝基化中的作用， 脊髓横断后的肌肉。假设：SCI后RyR的氧化/亚硝基化是由以下原因引起的： 增加Nox 4的表达和活性。Approach.目标1A。我们将比较SCI和假手术 在SCI后1至56天的不同时间段，在脊髓横断后随时间变化的组。我们将 检查RyR的氧化/亚硝基化和钙稳定蛋白的解离之间的时间关系 与Nox 4表达的变化。目的1B：Nox 4的条件性敲除在骨骼肌中的作用 肌肉对肌肉力量，比力，疲劳，RyR氧化后SCI将确定。目标1C：我们 将比较肌肉力量产生、比力、疲劳、RyR氧化/亚硝基化和RyR结合 用Nox 4抑制剂或载体处理的脊髓横断小鼠之间的钙稳定蛋白。 目的2）研究S107对大鼠骨骼肌肌力和RyR-钙稳定蛋白结合的影响 脊髓横断后的相互作用。假设：给予S107将改善肌肉 增加钙稳定蛋白与RyR的结合，但不会改变RyR 氧化/亚硝基化。方法：我们将比较肌肉比力，耐力，钙稳定蛋白的结合， RyR和RyR氧化/亚硝基化。 目标3。A）确定S107或Nox 4抑制剂是否改善了在治疗后的功能恢复， 挫伤性脊髓损伤假设：S107或Nox 4抑制剂改善分级挫伤的功能恢复 小鼠中胸SCI模型。方法：在轻度、中度或重度脊髓挫伤后 损伤，小鼠将用来自目的1和2的最有效的药物（S107或GKT 137831）治疗，或 车辆将确定治疗对运动功能和步态的影响。 对退伍军人的预期结果和好处。从此类研究中获得的知识可能会导致 新的药物或康复治疗，以改善SCI后的功能。