Post-SCI effects of BDNF and epidural stimulation on inhibitory RORb interneurons

SCI 后 BDNF 和硬膜外刺激对抑制性 RORb 中间神经元的影响

• 批准号: 10689714
• 负责人: Nicholas Stachowski
• 金额: $ 3.19万
• 依托单位: DREXEL UNIVERSITY
• 依托单位国家: 美国
• 财政年份: 2022
• 资助国家: 美国
• 起止时间: 2022-08-01 至 2023-12-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/10689714
• 关键词: Acute; Address; Adult; Affect; Behavior; Brain-Derived Neurotrophic Factor; Bypass; Cells; Chest; Chronic; Combined Modality Therapy; Electrophysiology (science); Fiber; Future; Genetic; Goals; Hindlimb; Hyperreflexia; In Vitro; Individual; Injury; Interneurons; Intervention; Lesion; Locomotor Recovery; Measures; Mediating; Methods; Motor; Mus; Neuronal Plasticity; Neurons; Neurotrophic Tyrosine Kinase Receptor Type 2; Nuclear Orphan Receptor; Orphan; Outcome; Paralysed; Pathway interactions; Physiological; Population; Protocols documentation; Receptor Activation; Recovery of Function; Rehabilitation therapy; Retinoids; Rodent; Role; Sensorimotor functions; Sensory Thresholds; Signal Transduction; Source; Spasm; Spinal; Spinal Cord; Spinal Injections; Spinal cord injury; Testing; Therapeutic; Therapeutic Intervention; Time; Transgenic Mice; Vertebral column; Viral; Weight; Work; central pattern generator; cohort; combinatorial; designer receptors exclusively activated by designer drugs; disability; dorsal horn; experimental study; functional improvement; improved; insight; loss of function; motor recovery; mouse model; nervous system disorder; neural; neurotransmission; neurotrophic factor; novel; novel therapeutic intervention; overexpression; pain reduction; patch clamp; presynaptic; prevent; receptor; recruit; rehabilitation strategy; sensory gating; sensory mechanism; side effect; spasticity; spinal nerve posterior root; synaptic inhibition; therapeutic target; treatment effect

ABSTRACT The number of individuals living with a spinal cord injury (SCI) continues to rise but rehabilitative strategies for functional locomotor recovery remain inadequate. Spinal circuits remain intact and functional even in the absence of descending control and serve as therapeutic targets. Neurotrophic factors have been shown to enhance neuronal plasticity and experimental viral overexpression of brain-derived neurotrophic factor (AAV- BDNF) is sufficient activate locomotor circuits to elicit alternating plantar stepping of hindlimbs after complete SCI in rodents. However, viral BDNF effects also induce a hyperreflexive state and hindlimb spasms. Sub-motor threshold epidural stimulation (ES) can reduce hyperreflexia in individuals living with SCI but the mechanism of action underlying this effect remains elusive. We have recently combined viral BDNF treatment with daily ES in a mouse model of complete SCI to identify synergistic effects between these two potentially complementary therapeutic strategies and our preliminary findings suggest a possible role for ES in mitigating BDNF-induced hyperreflexia while maintaining locomotor improvements. In addition to chronic disability, a large number of individuals living with SCI also suffer from hyperreflexia and our approach allows for exploration of treatment and mechanism in parallel. Spinal interneurons are the primary source of inhibitory control below the level of injury, and we will use precise physiological and genetic methods to identify the neural components subject to plasticity after SCI and subsequent intervention with viral BDNF, with or without ES. In this proposal, we focus on a population of inhibitory interneurons (INs) expressing the retinoid orphan nuclear receptor (RORb) which has recently been shown to gate low threshold sensory afferent signals via primary afferent depolarization (PAD), a spinal mechanism of presynaptic inhibition. RORb INs are likely to be affected by our combinatorial approach as they express TrkB receptors, the cognate receptor for BDNF, and are recruited upon activation of proprioceptive fibers, potential effector neurons of low intensity ES. Our central hypotheses are that: 1) BDNF increases the cellular excitability of RORb INs and enhances PAD pathway activity but this is insufficient to counteract other actions of BDNF leading to hyperreflexia, 2) the RORb-mediated PAD pathway is acutely enhanced during concurrent ES to limit BDNF-induced hyperreflexia and promote improvements in hindlimb stepping after complete SCI. We will investigate changes in the excitability of RORb INs at the presynaptic inhibitory circuit, together with behavior to determine the effects of SCI and treatment with BDNF alone and in combination with ES. This proposal will provide mechanistic insight into SCI-induced plasticity and identify therapeutic interactions that are associated with functional motor recovery as well as those underlying loss of function, both of which will benefit rehabilitative efforts to address intractable neurological disorders that extend beyond locomotor disability.

抽象的 脊髓损伤 (SCI) 患者的数量持续增加，但康复策略 功能性运动恢复仍然不足。即使在 缺乏下降控制并作为治疗目标。神经营养因子已被证明 增强神经元可塑性和脑源性神经营养因子（AAV- BDNF）足以激活运动回路，以在完成后引起后肢的交替足底踩踏 啮齿类动物的 SCI。然而，病毒性 BDNF 效应也会诱发反射亢进状态和后肢痉挛。副电机 阈值硬膜外刺激 (ES) 可以减少 SCI 患者的反射亢进，但其机制 这种效应背后的行动仍然难以捉摸。我们最近将病毒 BDNF 治疗与每日 ES 结合起来 完整 SCI 小鼠模型，用于鉴定这两种潜在互补性之间的协同效应 治疗策略和我们的初步研究结果表明 ES 在减轻 BDNF 诱导的 反射亢进，同时保持运动改善。除了慢性残疾之外，还有大量 脊髓损伤患者也患有反射亢进，我们的方法可以探索治疗方法和 并行机制。脊髓中间神经元是损伤水平以下抑制控制的主要来源， 我们将利用精确的生理学和遗传学方法来识别具有可塑性的神经成分 SCI 后以及随后的病毒 BDNF 干预（伴或不伴 ES）。在本提案中，我们重点关注 表达类维生素A孤儿核受体（RORb）的抑制性中间神经元（IN）群体，其具有 最近被证明可以通过初级传入去极化（PAD）来门控低阈值感觉传入信号，这是一种 脊髓突触前抑制机制。 RORb IN 可能会受到我们组合方法的影响，因为 它们表达 TrkB 受体（BDNF 的同源受体），并在本体感觉激活时被招募 纤维，低强度 ES 的潜在效应神经元。我们的中心假设是：1）BDNF 增加 RORb IN 的细胞兴奋性并增强 PAD 通路活性，但这不足以抵消其他 BDNF 的作用导致反射亢进，2）RORb 介导的 PAD 通路在 并发 ES 限制 BDNF 诱导的反射亢进并促进后肢迈步的改善 完整的SCI。我们将研究突触前抑制回路中 RORb IN 的兴奋性变化， 结合行为来确定 SCI 和单独使用 BDNF 以及联合使用 BDNF 治疗的效果 ES。该提案将为 SCI 诱导的可塑性提供机制见解并确定治疗相互作用 与功能性运动恢复以及潜在的功能丧失相关，两者都会 有利于康复治疗，以解决超出运动障碍范围的顽固性神经系统疾病。