Mol Pain
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Neuropathic pain is a common dose-limiting side effect of oxaliplatin, which hampers the effective treatment of tumors. Here, we found that upregulation of transcription factor NFATc2 decreased the expression of Beclin-1, a critical molecule in autophagy, in the spinal dorsal horn, and contributed to neuropathic pain following oxaliplatin treatment. ⋯ Further assays revealed that NFATc2 regulated histone H4 acetylation and methylation in the TSC2 promoter site 1 in rats' dorsal horns with oxaliplatin treatment. These results suggested that NFATc2 mediated the epigenetic downregulation of the TSC2/Beclin-1 autophagy pathway and contributed to oxaliplatin-induced mechanical allodynia, which provided a new therapeutic insight for chemotherapy-induced neuropathic pain.
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Neurosensory disorders such as pain and pruritus remain a major health problem greatly impacting the quality of life, and often increasing the risk of mortality. Current pre-clinical models to investigate dysfunction of sensory neurons have shown a limited clinical translation, in part, by failing to mimic the compartmentalized nociceptor anatomy that exhibits a central compartment containing the soma and a peripheral one harboring the axon endings with distinct molecular and cellular environmental composition. Thus, there is a need to validate compartmentalized preclinical neurosensory models for investigating the pathophysiology of peripheral sensory disorders and to test drug candidates. ⋯ Furthermore, compartmentalized nociceptor primary cultures were amenable to co-culture with keratinocytes in the axonal compartment. Interaction of axonal endings with keratinocytes modulated neuronal responses, consistent with a crosstalk between both cell types. These findings pave the way towards translational pre-clinical sensory models for skin pathophysiological research and drug development.
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Bone cancer pain (BCP) is severe chronic pain caused by tumor metastasis to the bones, often resulting in significant skeletal remodeling and fractures. Currently, there is no curative treatment. Therefore, insight into the underlying mechanisms could guide the development of mechanism-based therapeutic strategies for BCP. ⋯ Intrathecal injection of NSC23766, a Rac1 inhibitor, reduced the persistence of BCP as well as reversed the remodeling of dendrites. Therefore, we concluded that activation of the Rac1/PAK1 signaling pathway in the spinal cord plays an important role in the development of BCP through remodeling of dendritic spines. Modulation of the Rac1/PAK1 pathway may be a potential strategy for BCP treatment.
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Background: Opioids are efficacious and safe analgesic drugs in short-term use for acute pain but chronic use can lead to tolerance and dependence. Opioid-induced microglial activation may contribute to the development of tolerance and this process may differ between males and females. A link is suggested between this microglial activation and inflammation, disturbances of circadian rhythms, and neurotoxic effects. ⋯ This was associated with decreased staining of spinal microglia, suggesting either decreased activation or apoptosis. High-dose morphine administration also associated with several changes in gene expression in SC microglia, e.g., those related to the circadian rhythm (Per2, Per3, Dbp). These changes should be considered in the clinical consequences of long-term high-dose administration of opioids.
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Chemotherapy-induced peripheral neuropathy (CIPN) is a debilitating, treatment-limiting, side-effect of several classes of chemotherapy drugs. While negatively impacting oncology patients' quality of life, chemotherapy-induced large-fiber (LF) neuropathy is amongst the least well understood components of CIPN, and one for which there is currently no established therapy. Preliminary clinical observations have led to the suggestion that Duloxetine, which is used for the treatment of pain associated with small-fiber CIPN (SF-CIPN), may be effective against LF-CIPN. ⋯ We report that Bortezomib and Paclitaxel induce elevation of CPT, compatible with loss of large-fiber function, which are prevented by Duloxetine. Our findings support the clinical observation that Duloxetine may be an effective treatment for the large-fiber CIPN. We also suggest that CPT could be used as a biomarker for LF-CIPN in patients receiving neurotoxic chemotherapy.