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Levo-corydalmine Attenuates Vincristine-Induced Neuropathic Pain in Mice by Upregulating the Nrf2/HO-1/CO Pathway to Inhibit Connexin 43 Expression


Antimicrotubulin chemotherapeutic agents, including plant-derived vincaalkaloids such as vincristine, can cause peripheral neuropathic pain. Exogenously activated heme oxygenase 1 (HO-1) is a potential therapy for chemotherapy-induced neuroinflammation. In this study, we investigated a role for Nrf2/HO-1/CO in mediating vincristine-induced neuroinflammation by inhibiting connexin 43 (Cx43) production in the spinal cord following the intrathecal application of the HO-1 inducer protoporphyrin IX cobalt chloride (CoPP) or inhibitor protoporphyrin IX zinc (ZnPP), and we analyzed the underlying mechanisms by which levo-corydalmine (l-CDL, a tetrahydroprotoberberine) attenuates vincristine-induced pain. Treatment with levo-corydalmine or oxycodone hydrochloride (a semisynthetic opioid analgesic, used as a positive control) attenuated vincristine-induced persistent pain hypersensitivity and degeneration of the sciatic nerve. In addition, the increased prevalence of atypical mitochondria induced by vincristine was ameliorated by l-CDL in both A-fibers and C-fibers. Next, we evaluated whether nuclear factor E2-related factor 2 (Nrf2), an upstream activator of HO-1, directly bound to the HO-1 promoter sequence and degraded heme to produce carbon monoxide (CO) following stimulation with vincristine. Notably, l-CDL dose-dependently increased HO-1/CO expression by activating Nrf2 to inhibit Cx43 expression in both the spinal cord and in cultured astrocytes stimulated with TNF-α, corresponding to decreased Cx43-mediated hemichannel. Furthermore, l-CDL had no effect on Cx43 following the silencing of the HO-1 gene. Taken together, our findings reveal a novel mechanism by which Nrf2/HO-1/CO mediates Cx43 expression in vincristine-induced neuropathic pain. In addition, the present findings suggest that l-CDL likely protects against nerve damage and attenuates vincristine-induced neuroinflammation by upregulating Nrf2/HO-1/CO to inhibit Cx43 expression.

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Heme oxygenase 1


Nuclear factor E2-related factor 2


Carbon monoxide


Connexin 43


Protoporphyrin IX cobalt chloride


Protoporphyrin IX zinc


Glial fibrillary acidic protein


Phosphate-buffered saline


Dimethyl sulfoxide


Sodium dodecyl sulfate polyacrylamide gel electrophoresis


Vincristine-induced neuropathic pain


Chemotherapy-induced neuropathic pain


Small interfering RNA


Dulbecco’s Modified Eagle’s medium


Real-time quantitative polymerase chain reaction


Enzyme-linked immunosorbent assay


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This study was supported by the National Major Scientific and Technological Special Project for “Significant New Drugs Development” during the Thirteenth Five-year Plan Period (No. 2018ZX09301043-001 and No. 2016ZX09101031, respectively), National Natural Science Foundation of China (No. 81803642), the “Double First-Class” Construction Technology Innovation Team Project of China Pharmaceutical University (No. CPU2018GY23), and Postgraduate Research & Practice Innovation Program of Jiangsu Province (No. KYCX18_0804). We thank the State Key Laboratory of Natural Medicines (China Pharmaceutical University) for providing the large-scale instrument sharing platform.

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Zhou, L., Ao, L., Yan, Y. et al. Levo-corydalmine Attenuates Vincristine-Induced Neuropathic Pain in Mice by Upregulating the Nrf2/HO-1/CO Pathway to Inhibit Connexin 43 Expression. Neurotherapeutics 17, 340–355 (2020).

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Key Words

  • Vincristine
  • heme oxygenase 1
  • connexin-43
  • nuclear factor E2-related factor 2
  • neuropathic pain