Abstract
The etiology of neuropathic pain is mostly caused by mechanical deformation and neuroinflammation, of which neuroinflammation is the main cause of chronic neuropathic pain. Activation of the TLR4/NF-κB signaling pathway mediates elevated levels of inflammatory cytokines, and we clearly demonstrated by in vivo and in vitro Western blot experiments that β-sitosterol significantly inhibited the elevated Toll-like receptor 4 (TLR4) expression levels and nuclear factor-kappa B (NF-κB) activation associated with inflammatory responses. In cellular experiments, we clearly saw that both β-sitosterol and TLR4/NF-κB signaling pathway inhibitors could inhibit M1 proinflammatory phenotype expression and promote M2 anti-inflammatory phenotype expression in GMI-R1 microglia by flow cytometry and immunofluorescence assays. Therefore, we suggest that β-sitosterol can affect microglial polarization by inhibiting the TLR4/NF-κB signaling pathway thereby reducing neuroinflammation and thus alleviating neuropathic pain.
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Data Availability
The data used to support the findings of this study are available from the corresponding author upon request.
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Abbreviations
- TLR4:
-
Toll-like receptor 4
- MyD88:
-
Myeloid differentiation factor 88 l
- IKK:
-
IκB kinase
- IκB:
-
Inhibitor of NF-κB
- NF-κB:
-
Nuclear factor-Kappa B
- IL-1β:
-
Interleukin-1 beta
- IL-4:
-
Interleukin-4
- IL-6:
-
Interleukin-6
- IL-8:
-
Interleukin-8
- IL-10:
-
Interleukin-10
- TNF-α:
-
Tumor necrosis factor-alpha
- IFN-γ:
-
Interferon-γ
- Cox-2:
-
Cyclooxygenase-2
- IBA-1:
-
Ionized calcium binding adapter molecule 1
- iNOS:
-
Inducible Nitric Oxide Synthase
- Arg-1:
-
Arginase 1
- CCI:
-
Chronic constriction injury
- SD:
-
Sprague-Dawley
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Funding
This study was supported by the National Natural Science Foundation of China (grant no. 81874404; grant no. 82274294), China Postdoctoral Science Foundation (grant no. 2023TQ0135), Technology Innovation Team project (No. S2021TDZ085) of Guangdong Provincial Drug Administration.
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Yachun Zheng, Di Zhang and Guoping Zhao contributed substantially to the experimental design, data analysis, experimental procedures and wrote manuscript text. Shiquan Chang and Zifeng Zhuang assisted with the English writing. Si Waimei, Xin Li, Zenni Chen, Bei Jing reviewed the manuscript. Our special thanks to Yuyue Li for his support in image processing. Guoping Zhao and Di Zhang is the corresponding author. All data were generated in house, and no paper mill was used. All authors agree to be accountable for all aspects of the work and ensure its integrity and accuracy.
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Zheng, Y., Zhao, J., Chang, S. et al. β-Sitosterol Alleviates Neuropathic Pain by Affect Microglia Polarization through Inhibiting TLR4/NF-κB Signaling Pathway. J Neuroimmune Pharmacol 18, 690–703 (2023). https://doi.org/10.1007/s11481-023-10091-w
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DOI: https://doi.org/10.1007/s11481-023-10091-w