Mol Pain
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Treating bone cancer pain continues to be a clinical challenge and underlying mechanisms of bone cancer pain remain elusive. Here, we reported that sonic hedgehog signaling plays a critical role in the development of bone cancer pain. Tibia bone cavity tumor cell implantation produces bone cancer-related mechanical allodynia, thermal hyperalgesia, and spontaneous and movement-evoked pain behaviors. ⋯ Spinal administration of sonic hedgehog signaling inhibitor cyclopamine prevents and reverses the induction and persistence of bone cancer pain without affecting normal pain sensitivity. Inhibiting sonic hedgehog signaling activation with cyclopamine, in vivo or in vitro, greatly suppresses tumor cell implantation-induced increase of intracellular Ca2+ and hyperexcitability of the sensory neurons and also the activation of GluN2B receptor and the subsequent Ca2+-dependent signals CaMKII and CREB in dorsal root ganglion and the spinal cord. These findings show a critical mechanism underlying the pathogenesis of bone cancer pain and suggest that targeting sonic hedgehog signaling may be an effective approach for treating bone cancer pain.
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Opioid receptors play an important role in mediating the spinal analgesia. The μ-opioid receptor is the major target of opioid drugs widely used in clinics. However, the regulatory mechanisms of analgesic effect and tolerance for clinical μ-opioid receptor-targeting opioids remain to be fully investigated. ⋯ Prolonged treatment of morphine led to μ-opioid receptor co-degradation with δ-opioid receptors. Furthermore, fentanyl and methadone, but not tramadol, induced the drug tolerance similar to morphine. Thus, the clinical μ-opioid receptor-targeting opioids including morphine, fentanyl, and methadone induce μ-opioid receptor co-internalization with δ-opioid receptors, which may be involved in the analgesic tolerance of these opioids.
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Spinal nociceptive transmission receives biphasic modulation from supraspinal structures. Recent studies demonstrate that the anterior cingulate cortex facilitates spinal excitatory synaptic transmission and nociceptive reflex. However, whether the top-down descending facilitation can cause long-term synaptic changes in spinal cord remains unclear. ⋯ Spinal application of N-methyl-D-aspartate (NMDA) receptor antagonist D-AP5 abolished this enhancement, suggesting that the activation of the NMDA receptor is required. Furthermore, spinal application of methysergide, a serotonin receptor antagonist, also blocked the anterior cingulate cortex-induced spinal long-term potentiation. Our results suggest that the anterior cingulate cortex stimulation can produce heterosynaptic form of long-term potentiation at the spinal cord dorsal horn, and this novel form of long-term potentiation may contribute to top-down long-term facilitation in chronic pain conditions.
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Jung Ye-Ha, Kim H, Jeon SY, Kwon JM, Lee D, Choi Soo-Hee and Kang Do-Hyung. Aberrant interactions of peripheral measures and neurometabolites with lipids in complex regional pain syndrome using magnetic resonance spectroscopy: A pilot study. ⋯ The authors regret this error. Lip09-dependent right thalamus and Lip13a-dependent left thalamus may be important to elucidate abnormal interactions between lipids in the central thalamus and peripheral measures in CRPS patients, suggestive of unique mechanisms underlying lipidassociated pathophysiology in CRPS, These findings may be used to develop personalized therapies according to the dominant side of the thalamus (right versus left) and the presence and interactions of specific metabolites.
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Objective Neural stem cells play an important role in the recovery and regeneration of peripheral nerve injury, and the microRNA-7 (miR-7) regulates differentiation of neural stem cells. This study aimed to explore the role of miR-7 in neural stem cells homing and proliferation and its influence on peripheral nerve injury repair. Methods The mice model of peripheral nerve injury was created by segmental sciatic nerve defect (sciatic nerve injury), and neural stem cells treatment was performed with a gelatin hydrogel conduit containing neural stem cells inserted into the sciatic nerve injury mice. ⋯ Using co-transfection into neural stem cells, we found pcDNA3.1-cdc42 and si-cdc42 could reverse respectively the role of miR-7 mimic and miR-7 inhibitor on neural stem cells migration and proliferation. In addition, miR-7 mimic-transfected neural stem cells could abolish the protective role of neural stem cells on peripheral nerve injury. Conclusion MiR-7 inhibited peripheral nerve injury repair by affecting neural stem cells migration and proliferation through cdc42.