Modulation of the prefrontal cortical network in neuropathic pain

摘要 慢性疼痛的神经生物学基础知之甚少，也没有经过科学验证的治疗方法。 这样的条件。然而，慢性疼痛造成了巨大的社会经济代价，估计高达6350亿美元 每年的医疗成本和生产力损失。更糟糕的是，大多数阿片类药物滥用者开始 他们对治疗慢性疼痛的处方药上瘾。因此，寻找新的非阿片类药物， 慢性疼痛的药物治疗构成了最紧迫的未得到满足的医疗需求之一。旁边 其感觉症状，慢性疼痛的特征是认知任务的损害，如注意力和 工作记忆，依赖于内侧前额叶皮质(MPFC)的胆碱能调制。因此， MPFC失活被发现对神经病理性疼痛表型有因果作用，我们的初步研究 有资料表明，雄性大鼠mPFC锥体神经元兴奋性胆碱能调制功能严重受损。 然而，介导mPFC失活的确切机制，这种失活如何影响疼痛 知觉和认知表现，以及它是否同样影响男性和女性，在很大程度上仍然存在 未知。我们的初步数据显示，M1受体介导的电流对mPFC锥体起关键作用 细胞兴奋性在神经病理性疼痛中显著降低；我们的主要假设是 神经病理性疼痛中mPFC的胆碱能调节是mPFC失活的主要机制 并调节几种感觉、认知和情绪症状。特别是，我们假设在 神经病理性疼痛：(1)mPFC活动的胆碱能调节被破坏，这是导致 (2)阻断M1介导的mPFC兴奋足以模拟，在 至少在一定程度上，神经病理性疼痛表型；(3)抵消 胆碱能阻断和恢复mPFC输出改善神经病患者的认知和感觉症状 疼痛。为了验证这些假设，我们将利用神经病理性的备用神经损伤(SNI)模型 痛苦地追求两个特定的目标。在目标1中，我们将结合个体胆碱能的光遗传激活 输入、急性脑片的膜片钳记录和聚合酶链式反应分析，以检验损伤的假设 胆碱能调节有助于mPFC的整体失活，以确定受体的身份 并剖析来自局部中间神经元和基底神经元的胆碱能输入的相对影响。 女性和男性前脑对mPFC活性的影响。在目标2中，我们将测试受损的人的行为影响 MPFC胆碱能调制。我们将使用体内化学发生和药物调节的mPFC 逆转SNI表型。我们获得的初步数据显示，通过增强mPFC兴奋性 5HT1a受体的药理拮抗作用具有明显的镇痛作用。相反，我们还将 研究阻断M1介导的mPFC在幼年动物中的兴奋是否足以模拟SNI 表型。因此，我们的工作将确定非阿片类神经病理性疼痛治疗的新的潜在靶点。

Summary The neurobiological basis of chronic pain is poorly understood and no scientifically validated therapies exist for such condition. Yet, chronic pain has an enormous socio-economic price, estimated to reach US$ 635 billion annually in healthcare costs and lost productivity. To make things worse, the majority of opioid abusers begin their addiction with prescription medications for chronic pain. Consequently, the search for new, non-opioid, pharmacological treatments for chronic pain constitutes one of the most urgent unmet medical needs. Beside its sensory symptoms, chronic pain is characterized by impairment of cognitive tasks such as attention and working memory, which depend on cholinergic modulation of medial prefrontal cortex (mPFC). Accordingly, mPFC deactivation was found to have a causal role for the neuropathic pain phenotype, and our preliminary data show that excitatory cholinergic modulation is severely impaired in mPFC pyramidal neurons of male rats. Yet, the precise mechanisms mediating the mPFC deactivation, how this deactivation influences pain perception and cognitive performance, and whether it similarly impacts males and females remain largely unknown. Our preliminary data show that a current mediated by the M1 receptor is critical for mPFC pyramidal cell excitability and is strongly reduced in neuropathic pain; our overarching hypothesis is that impaired cholinergic modulation of the mPFC represents a major mechanism of mPFC deactivation in neuropathic pain and mediates several of the sensory, cognitive and emotional symptoms. In particular, we hypothesize that in neuropathic pain: (1) cholinergic modulation of mPFC activity is disrupted and this critically contributes to the global mPFC deactivation in both sexes; (2) blockade of M1-mediated mPFC excitation is sufficient to mimic, at least in part, the neuropathic pain phenotype; (3) pharmacological manipulations that counterbalance the cholinergic disruption and restore mPFC output ameliorate cognitive and sensory symptoms of neuropathic pain. To test these hypotheses we will take advantage of the Spared-Nerve-Injury (SNI) model of neuropathic pain to pursue two specific aims. In Aim 1 we will combine optogenetic activation of individual cholinergic inputs, patch clamp recordings in acute slices and PCR analysis, to test the hypothesis that impaired cholinergic modulation contributes to the global mPFC deactivation, to determine the identity of the receptors involved, and to dissect the relative impact of cholinergic inputs from local interneurons and from the basal forebrain on mPFC activity in both females and males. In Aim 2 we will test the behavioral effects of impaired mPFC cholinergic modulation. We will use in-vivo chemogenetic and pharmacological modulation of the mPFC to reverse the SNI phenotype. We obtained preliminary data showing that enhancing mPFC excitability through pharmacological antagonism of the 5HT1a receptor has potent analgesic effects. Conversely, we will also investigate whether blockade of M1-mediated mPFC excitation in naive animals is sufficient to mimic the SNI phenotype. Our work will thus identify new potential targets for non-opioid neuropathic pain treatment.