Glycine receptor synaptic plasticity

描述(申请人提供)：尽管甘氨酸受体在神经系统中与人类健康相关的关键区域非常重要，但对甘氨酸能突触强度的调节知之甚少，对功能回路中的甘氨酸能突触更是知之甚少。甘氨酸能突触构成了脊髓、脑干和中脑中的许多抑制性驱动控制网络，调节运动行为、节律产生、躯体感觉、听觉和视网膜信号，以及反射反应的协调。我们的长期目标是了解如何控制中枢神经系统中甘氨酸能突触的强度，为脊髓和脑干回路障碍提供新的药物靶点。这项研究提案的目的是通过对青春期小鼠完整的脊髓切片进行功能研究，确定甘氨酸能突触的增强是如何触发和维持的。利用脊髓切片的电生理记录，我们发现炎性细胞因子IL-1β迅速上调了背角抑制性神经元上的抑制性甘氨酸受体。据我们所知，这是中枢神经系统甘氨酸受体长时程增强(LTP)的第一个例子。抑制性背角神经元的快速抑制有望促进疼痛信号向大脑的传递，这可能是鞘内IL-1β已知的伤害性效应的原因之一。我们的初步数据支持在此应用中验证的假设：外周损伤后在背角释放的IL-1β激活细胞黏附分子和细胞内蛋白激酶级联，迅速增加突触甘氨酸能受体的数量。这项研究的基本原理是，通过识别正常情况下控制甘氨酸能突触强度的信号级联反应，我们将提供治疗疼痛和其他甘氨酸受体依赖性疾病的新靶点。拟议的实验将主要依靠脊髓切片中敏感的电生理记录，阐明甘氨酸能LTP(目标1和2)所涉及的信号通路和受体亚型。我们的初步结果还表明，体内炎症增强了甘氨酸能突触，类似于体外观察到的IL-1β增强。因此，我们将确定甘氨酸受体LTP在外周炎症后的作用 (目标3)，使用电生理和行为分析。在我们看来，这项工作具有创新性，因为1)我们在哺乳动物中枢神经系统的甘氨酸能突触上首次发现了LTP，2)突触的可塑性可以作为病理的基础，揭示其潜在的机制为控制疾病中的甘氨酸能突触提供了一条新的途径。这项研究的贡献将是阐明在发达的组织环境中甘氨酸受体信号和突触增强的潜在机制，目前尚不完全清楚。这些贡献意义重大，因为它们是开发疼痛、呼吸和运动障碍以及听力障碍新疗法的关键第一步。

DESCRIPTION (provided by applicant): Despite the great importance of glycine receptors in key areas of the nervous system with relevance for human health, remarkably little is known about the regulation of glycinergic synapse strength, and even less about glycinergic synapses in functional circuits. Glycinergic synapses comprise much of the inhibitory drive controlling networks in the spinal cord, brainstem and midbrain, regulating motor behavior, rhythm generation, somatosensory, auditory, and retinal signaling, and coordination of reflex responses. Our long-term goal is to understand how to control the strength of glycinergic synapses in the central nervous system to provide novel drug targets for disorders of spinal cord and brainstem circuits. The objective of this research proposal is to define how potentiation of glycinergic synapses is triggered and maintained, using functional studies in intact spinal cord slices from adolescent mice. Using electrophysiological recordings in spinal cord slices, we find that the inflammatory cytokine, IL-1beta, rapidly upregulates inhibitory glycine receptors on inhibitory neurons in the dorsal horn. To our knowledge, this is the first example of long-term potentiation (LTP) of glycine receptors anywhere in the CNS. The rapid inhibition of inhibitory dorsal horn neurons is expected to promote the transmission of pain signals to the brain, likely contributing to the known nociceptive effects of intrathecal IL-1beta. Our preliminary data support the hypothesis to be tested in this application: that IL-1beta released in the dorsal horn by peripheral injury activates cell adhesion molecules and intracellular protein kinase cascades, rapidly increasing synaptic glycinergic receptor numbers. The rationale for the proposed research is that by identifying the signaling cascades that normally control glycinergic synapse strength, we will provide novel therapeutic targets to treat pain and other glycine receptor-dependent disorders. Proposed experiments will elucidate the signaling pathways and receptor subtypes involved in glycinergic LTP (Aims 1 and 2), primarily relying on sensitive electrophysiological recordings in spinal cord slices. Our preliminary results also indicate that inflammation in vivo potentiates glycinergic synapses, similarly to IL-1beta potentiation observed in vitro. We will therefore identify the role of glycine receptor LTP after peripheral inflammation (Aim 3), using electrophysiological and behavioral assays. The proposed work is innovative, in our opinion, because 1) we have identified the first example of LTP at glycinergic synapses in the mammalian CNS, and 2) as synaptic plasticity can underlie pathology, delineating the underlying mechanisms offers a new way to control glycinergic synapses in disease. The contributions of this research will be the elucidation of as yet entirely unknown mechanisms underlying glycine receptor signaling and synaptic potentiation in a developed tissue setting. These contributions are significant because they constitute critical first steps towards the development of new treatments for pain, respiratory and motor disorders, and auditory disorders.