ERK/MAPK Activation and Pain Hypersensitivity

临床疼痛可由组织损伤(炎症性疼痛)和神经损伤(神经病理性疼痛)引起，典型的特征是痛觉过敏(对伤害性刺激的反应增加)和超敏(对无害的刺激的疼痛反应)。初级感觉神经元外周终末的改变可能导致外周敏化(伤害性感受器的转导敏感性增加)，而脊髓背角神经元兴奋性的变化可以导致中枢敏化(感觉传递增加)，这是导致疼痛超敏的两个主要机制。虽然短期疼痛超敏反应不依赖于转录，但持续性疼痛超敏反应可能是基因转录和蛋白质合成依赖机制的结果。该建议的目的是评估MAPK(丝裂原活化蛋白激酶)家族成员ERK(细胞外信号调节蛋白激酶)在介导翻译后和转录后变化中的作用，这些变化有助于炎症和神经病理性疼痛超敏。该项目将在体内和体外检测背根神经节(DRG)和背角神经元中ERK的激活情况，并将检验以下假设：1)ERK激活有助于外周和中枢敏化，2)ERK激活导致CREB磷酸化，并在DRG和背角神经元中表达含CRE的基因，3)ERK激活有助于炎性痛和神经病理性痛的诱导和维持。将使用许多不同的方法，包括免疫染色、蛋白质印迹和原位杂交来检测蛋白质和信使核糖核酸的表达，以及行为测试。这些结果应该为深入了解细胞内信号转导级联在疼痛发病机制中的作用提供依据。

Clinical pain can be caused by tissue injury (inflammatory pain) and by nerve injury (neuropathic pain) and is typically characterized by hyperalgesia (increased responsiveness to noxious stimuli) and allodynia (painful responses to innocuous stimuli). Changes in the peripheral terminals of primary sensory neurons may lead to peripheral sensitization (an increased transduction sensitivity of nociceptors) whilst changes in the excitability of spinal dorsal horn neurons can result in central sensitization (an increased gain of sensory transmission), two major mechanisms contributing to pain hypersensitivity. Although short-term pain hypersensitivity is transcription-independent, persistent pain hypersensitivity may be the result of gene transcription- and protein synthesis-dependent mechanisms. The aim of this proposal is to assess the involvement of the MAPK (mitogen-activated protein kinase) family member ERK (extracellular signal-regulated protein kinase) in mediating both post-translational and transcriptional changes which contribute to inflammatory and neuropathic pain hypersensitivity. The project will examine ERK activation in primary sensory neurons in the dorsal root ganglia (DRG) and in dorsal horn neurons in vivo and in vitro and will test the hypotheses that 1) ERK activation contributes to peripheral and central sensitization, 2) ERK activation leads to CREB phosphorylation and the expression of CRE-containing genes in DRG and dorsal horn neurons, and 3) ERK activation contributes to the induction and maintenance of inflammatory pain and neuropathic pain. A number of different approaches, including immunostaining, western blot, and in situ hybridization to detect protein and mRNA expression, will be used, as well as behavioral tests. These results should provide insights into the role of intracellular signal transduction cascades in the pathogenesis of pain.