Project description:Trigeminal neuralgia (TN) is a type of neuropathic pain caused by injury to sensory nerves, manifesting as severe paroxysmal pain of the head and face. Trigeminal neuralgia brings a huge burden to patients, without long-term effective treatment. Changes in the expression of pain-related genes in the whole blood samples of patients play an important role in the pathogenesis, diagnosis, and evaluation of treatment effects of trigeminal neuralgia. To better understand the mechanism of trigeminal neuralgia, we collect the whole blood samples from the trigeminal neuralgia patients and the pain-free healthy comparisons. RNA-seq was conducted between the two groups to find the transcriptome changes in patients with trigeminal neuralgia.
Project description:The cerebral cortex plays a key role in the multi-dimensional human pain experience. However, the neural mechanisms mediating pain-related cortical activity remain largely unknown, particularly in primary somatosensory cortex (S1). We therefore developed a new animal model of trigeminal neuralgia, a prototypical neuropathic pain, which allowed us to evaluate pain-related cortical dynamics with unprecedented translational relevance. Our novel model (FLIT: Foramen Lacerum Impingement of Trigeminal-nerve) displayed robust clinically relevant trigeminal neuralgia-like behaviors, including asymmetric facial grimacing, dental pain-like behaviors, anxiety-like behavior, and sexual dysfunction, capturing many features of the human pain experience. Awake FLIT mice exhibited highly synchronized spontaneous population activity in S1, due to GABAergic interneuron hypoactivity. Remarkably, clinically effective treatments including carbamazepine and trigeminal nerve root decompression abrogated S1 synchronization and alleviated trigeminal neuralgia-like behaviors. These results reveal synchronized S1 activity as a new and important cortical substrate of neuropathic pain, which can be clinically targeted to provide effective therapy.
Project description:Beta-endorphinergic neurons in the hypothalamic arcuate nucleus (ARC) synthesize beta-endorphin (β-EP) to alleviate nociceptive behaviors, although the underlying regulatory mechanisms remain unknown. Here, we elucidated a novel epigenetic pathway driven by microRNA regulation of beta-endorphin synthesis in ARC neurons to control neuropathic pain. In pain-injured rats miR-203a-3p was the most highly upregulated miRNA in the ARC. A similar increase was identified in the cerebrospinal fluid of trigeminal neuralgia patients. Mechanistically, histone deacetylase 9 downregulation increased acetylation of histone H3 lysine-18, facilitating the binding of NR4A2 transcription factor to the miR-203a-3p gene promoter increasing miR-203a-3p expression following nerve injury. Further, increased miR-203a-3p was found to maintain neuropathic pain by targeting proprotein convertase 1, an endopeptidase necessary for the cleavage of proopiomelanocortin, the precursor of β-EP. Our findings highlight an epigenetic regulatory pathway for β-EP synthesis that contributes to neuropathic pain development and maintenance mechanisms providing for new therapeutic targets for neuropathic pain treatment.
Project description:Neuropathic pain is an apparently spontaneous experience triggered by abnormal physiology of the peripheral or central nervous system, which evolves with time. Neuropathic pain arising from peripheral nerve injury is characterized by a combination of spontaneous pain, hyperalgesia and allodynia. There is no evidence of this type of pain in human infants or rat pups; brachial plexus avulsion, which causes intense neuropathic pain in adults, is not painful when the injury is sustained at birth. Since infants are capable of nociception from before birth and display both acute and chronic inflammatory pain behaviour from an early neonatal age, it appears that the mechanisms underlying neuropathic pain are differentially regulated over a prolonged postnatal period. We used microarrays to detail the global programme of gene expression underlying the differences in nerve injury between along the postnatal development and identified distinct classes of regulated genes during the injury Experiment Overall Design: We have performed a microarray analysis of the rat L4/L5 dorsal root ganglia, 7 days post spared nerve injury, a model of neuropathic pain. Genes that are regulated in adult rats displaying neuropathic behaviour were compared to those regulated in young rats (10 days old) that did not show the same neuropathic behaviour.
Project description:Pain sensing neurons, nociceptors, are key drivers of neuropathic pain. We used translating ribosome affinity purification (trap) to comprehensively characterize up- and down-regulated mRNA translation in Scn10a-positive nociceptors in chemotherapy-induced neuropathic pain. We provide evidence that an underlying mechanism driving these changes in gene expression is a sustained mTORC1 activation driven by MNK1-eIF4E signaling. RagA, a GTPase controlling mTORC1 activity, is identified as a novel target of MNK1-eIF4E signaling, demonstrating a new link between these distinct signaling pathways. Neuropathic pain and RagA translation are strongly attenuated by genetic ablation of eIF4E phosphorylation, MNK1 elimination or treatment with the MNK inhibitor eFT508. We reveal a novel translational circuit for the genesis of neuropathic pain with important implications for next generation neuropathic pain therapeutics.
Project description:Neuropathic pain is an apparently spontaneous experience triggered by abnormal physiology of the peripheral or central nervous system, which evolves with time. Neuropathic pain arising from peripheral nerve injury is characterized by a combination of spontaneous pain, hyperalgesia and allodynia. There is no evidence of this type of pain in human infants or rat pups; brachial plexus avulsion, which causes intense neuropathic pain in adults, is not painful when the injury is sustained at birth. Since infants are capable of nociception from before birth and display both acute and chronic inflammatory pain behaviour from an early neonatal age, it appears that the mechanisms underlying neuropathic pain are differentially regulated over a prolonged postnatal period. We used microarrays to detail the global programme of gene expression underlying the differences in nerve injury between along the postnatal development and identified distinct classes of regulated genes during the injury
Project description:Intractable neuropathic pain is recognized as a common symptom of neuromyelitis optica spectrum disorder (NMOSD). However, the underlying mechanism of NMOSD pain remains to be elucidated. Here, we established NMOSD pain model by injecting anti-AQP4 recombinant autoantibodies (AQP4-Ab) generated from NMOSD patient’s plasmablasts into rat spinal cords and confirmed the development of mechanical allodynia. AQP4-Ab mediated extracellular ATP release from astrocytes and pharmacological inhibition of ATP receptor reversed mechanical allodynia in NMOSD pain model. Furthermore, transcriptome analysis revealed microglia activation and IL-1β elevation in NMOSD spinal cord. Inhibition of microglia activation and neutralization of IL-1β also attenuated neuropathic pain in NMOSD rat model. In addition, the human CSF ATP concentration was significantly higher in the acute and remission phase of NMOSD than in multiple sclerosis and other neurological disorder patients. These findings indicate ATP, microglial activation and IL-1β secretion orchestrates the pathogenesis of NMOSD neuropathic pain.
Project description:Neuropathic pain is a refractory condition that involves de novo protein synthesis in the nociceptive pathway. The mechanistic target of rapamycin (mTOR) is a master regulator of protein synthesis; however, mechanisms underlying its role in neuropathic pain remain elusive. Using spared nerve injury-induced neuropathic pain model, we found mTOR activation in large-diameter dorsal root ganglion (DRG) neurons and spinal microglia. However, selective ablation of mTOR in DRG neurons, rather than microglia, alleviated neuropathic pain. Combining transcriptomic profiling, electrophysiological recording and pharmacologic manipulations, we demonstrated that activated mTOR promoted neuropeptide Y (NPY) induction in mechanoreceptors and that NPY acted on Y2 receptors (Y2R) but not Y1R to enhance nociceptor excitability. Peripheral replenishment of NPY reversed pain alleviation upon mTOR removal, whereas Y2R antagonists prevented its function. Our findings reveal an unexpected link between mTOR and NPY in promoting nociceptor sensitization and neuropathic pain, through NPY/Y2R signaling-mediated intra-ganglionic transmission.
Project description:Oxaliplatin-induced neuropathic pain is a common dose-limiting side effect of cancer treatment but the underlying mechanisms are largely unknown. The neuropathic pain model was established by oxaliplatin intraperitoneal administration for five consecutive days. In the present study, we performed whole genome expression microarray analysis by using spinal dorsal horn from oxaliplatin-treated and vehicle-treated rats on day 10.