Do Rorb/calretinin interneurons (CR islet cells) gate spinal nociceptive inputs?

Rorb/钙结合蛋白中间神经元（CR 胰岛细胞）是否控制脊髓伤害性输入？

• 批准号: BB/P007996/1
• 负责人: David Hughes
• 金额: $ 63.5万
• 依托单位: University of Glasgow
• 依托单位国家: 英国
• 项目类别: Research Grant
• 财政年份: 2017
• 资助国家: 英国
• 起止时间: 2017 至 无数据
• 项目状态: 已结题
• 来源: https://gtr.ukri.org/projects?ref=BB%2FP007996%2F1
• 关键词: Do; Rorb; calretinin; interneurons; CR

Nerve fibres that enter the spinal cord (primary afferent fibres) carry various types of sensory information. Some of these fibres (nociceptors) respond to tissue-damaging stimuli that are normally perceived as pain. Although nociceptors are found in tissues throughout the body, one particular class, known as C-MrgD afferents, exclusively supplies the skin. Selective destruction of the C-MrgD afferents in mice leads to reduced pain behaviour following mechanical stimuli, but not hot or cold stimuli. This suggests that these afferents are required for the normal perception of mechanical pain. Primary afferent fibres activate a variety of nerve cells in the spinal cord. Most of these cells are interneurons, which give rise to local circuits that process and modify the incoming sensory information before it is conveyed to the brain for conscious perception. Around a third of these interneurons release chemical messengers (neurotransmitters) that reduce the activity of other nerve cells, and therefore have an inhibitory function. These inhibitory interneurons use two basic mechanisms: postsynaptic and presynaptic inhibition. Postsynaptic inhibition involves suppressing activity of nearby nerve cells, while presynaptic inhibition operates directly on the incoming sensory nerve fibres by reducing their ability to activate their target cells. This has the advantage of providing a highly selective inhibition of specific types of sensory information. Presynaptic inhibition is known to operate on C-MrgD afferents, and this will presumably suppress pain. Until recently nothing was known about the inhibitory interneurons responsible for this, but we have now identified a population of cells that presynaptically inhibit the C-MrgD afferents. These cells can be recognised because they contain two proteins: calretinin (CR) and Rorb. These proteins are only co-localised in this population, and because of their morphology we have called them CR islet cells. These findings are important because they provide a way of investigating the role of presynaptic inhibition of nociceptors in pain mechanisms.In this project, we will use a multi-disciplinary approach to test a set of hypotheses concerning the CR islet cells. We will use genetically altered mice in which specific populations of nerve cells are labelled with fluorescent markers and/or contain proteins that allow their functions to be manipulated, either by application of light pulses or through the administration of highly selective drugs. We will initially carry out physiological studies to test the hypothesis that the CR islet cells are the major source of presynaptic inhibition of the C-MrgD afferents and that they can block the transmission of activity evoked by these afferents in spinal cord nerve cells. We know that the C-MrgD afferents are not the only target for the CR islet cells, and we will therefore test whether they also inhibit excitatory nerve cells that are activated by these afferents. If so, this would allow the CR islet cells to generate a powerful inhibition of the transmission of pain information from nociceptive primary afferents to the projection cells that convey this information to the brain, and represent the main output for spinal cord pain circuits. Finally, we will use genetically altered mice to activate the CR islet cells selectively in vivo. We predict that this will alleviate the hypersensitivity to mechanical stimuli that occurs in pathological pain states, and we will use behavioural testing in standard models of inflammatory and nerve injury-evoked pain to determine whether this is the case.These experiments will greatly improve our understanding of the nerve circuits in the spinal cord that are responsible for controlling pain. This information is important in the search for new drugs to treat pain, and also for future studies to investigate changes in the spinal cord that underlie chronic pain states.

进入脊髓（主要传入纤维）的神经纤维带有各种类型的感觉信息。这些纤维中的一些（伤害感受器）对通常被视为疼痛的组织损伤刺激有反应。尽管在整个身体的组织中发现了伤害感受器，但一种特定的类别（称为C-MRGD传入）仅提供皮肤。小鼠中C-MRGD传入的选择性破坏会导致机械刺激后的疼痛行为减少，但不能减少刺激，但不能减少刺激。这表明这些传入是对机械疼痛的正常感知所必需的。初级传入纤维激活脊髓中的各种神经细胞。这些细胞中的大多数是中间神经元，它会引起局部电路，这些电路在将传入的感觉信息传达给大脑之前，以使其有意识。这些中神经元中有大约三分之一释放化学信使（神经递质），从而降低其他神经细胞的活性，因此具有抑制功能。这些抑制性中间神经元使用两种基本机制：突触后和突触前抑制作用。突触后抑制涉及抑制附近神经细胞的活性，而突触前抑制作用通过降低其激活目标细胞的能力直接在传入的感觉神经纤维上进行。这具有对特定类型的感觉信息的高度选择性抑制的优点。众所周知，突触前抑制作用可在C-MRGD传入中作战，这可能会抑制疼痛。直到最近，对负责此的抑制性神经元的抑制性中间神经元一无所知，但是我们现在已经确定了突触前抑制C-MRGD传入的细胞群。这些细胞可以被识别，因为它们含有两种蛋白质：钙化蛋白（CR）和RORB。这些蛋白质仅在该人群中共定位，并且由于它们的形态，我们称它们为CR胰岛细胞。这些发现很重要，因为它们提供了一种调查伤害感受器在疼痛机制中的突触前抑制作用的方法。在该项目中，我们将使用多学科方法来测试有关CR ISLET细胞的一组假设。我们将使用遗传改变的小鼠，其中特定的神经细胞群标有荧光标记物和/或包含蛋白质，可以通过应用光脉冲或通过施用高度选择性的药物来操纵其功能。我们最初将进行生理研究，以检验以下假设：CR胰岛细胞是对C-MRGD传统的突触前抑制前的主要来源，并且它们可以阻止这些传入脊髓神经细胞中这些传入的活性传播的传播。我们知道，C-MRGD传入并不是CR胰岛细胞的唯一目标，因此我们将测试它们是否还抑制这些传入者激活的兴奋性神经细胞。如果是这样，这将使CR胰岛细胞能够强大抑制从伤害感受性的初级传入到将该信息传达给大脑的投影细胞的传播，并代表脊髓疼痛电路的主要输出。最后，我们将使用基因改变的小鼠在体内选择性地激活CR胰岛细胞。我们预测，这将减轻病理疼痛状态中发生的机械刺激的超敏反应，我们将在炎症和神经损伤诱发的疼痛的标准模型中使用行为测试来确定是否是这种情况。这些实验将大大提高我们对负责控制疼痛的脊髓中神经通心的理解。该信息对于寻找治疗疼痛的新药以及将来的研究以调查慢性疼痛状态的脊髓变化很重要。

项目成果

Projection Neuron Axon Collaterals in the Dorsal Horn: Placing a New Player in Spinal Cord Pain Processing.

• DOI: 10.3389/fphys.2020.560802
• 发表时间: 2020
• 期刊: Frontiers in physiology
• 影响因子: 4
• 作者: Browne TJ;Hughes DI;Dayas CV;Callister RJ;Graham BA
• 通讯作者: Graham BA

Neuropeptide Y-expressing dorsal horn inhibitory interneurons gate spinal pain and itch signalling.

• DOI: 10.7554/elife.86633
• 发表时间: 2023-07-25
• 期刊: eLife
• 影响因子: 7.7
• 作者: Boyle KA;Polgar E;Gutierrez-Mecinas M;Dickie AC;Cooper AH;Bell AM;Jumolea E;Casas-Benito A;Watanabe M;Hughes DI;Weir GA;Riddell JS;Todd AJ
• 通讯作者: Todd AJ

Defining a Spinal Microcircuit that Gates Myelinated Afferent Input: Implications for Tactile Allodynia

定义门控有髓鞘传入输入的脊髓微电路：对触觉异常性疼痛的影响

• DOI: 10.2139/ssrn.3377640
• 发表时间: 2019
• 期刊: SSRN Electronic Journal
• 作者: Boyle K

Neuropeptide Y-expressing dorsal horn inhibitory interneurons gate spinal pain and itch signalling

• DOI: 10.1101/2023.02.10.528013
• 发表时间: 2023-03
• 期刊: bioRxiv
• 作者: K. Boyle;E. Polgár;M. Gutierrez-Mecinas;A. Dickie;Andrew H. Cooper;Andrew M. Bell;M. Evelline Jumolea;Adrián Casas-Benito;Masahiko Watanabe;D. Hughes;Gregory A Weir;J. Riddell;A. Todd