PDTC ameliorates neuropathic pain by inhibiting microglial activation <em>via</em> blockage of the TNFα-CX3CR1 pathway

Eur J Histochem. 2021 Mar 12;65(1):3184. doi: 10.4081/ejh.2021.3184.

Abstract

Previous studies have suggested that pyrrolidine dithiocarbamate (PDTC), a nuclear factor κB (NF-κB) inhibitor, play a role in deterring nerve injury-induced neuropathic pain (NP) The activation of NF-κB pathway may contribute to spinal microglial activation, CX3CR1 and tumor necrosis factor-alpha (TNF-a) up-regulation. The aim of this study was to clarify whether PDTC could inhibit the development of neuropathic pain via decreasing TNF-a-induced CX3CR1 up-regulation. Sprague-Dawley rats were randomly divided into sham group and NP group. Rats in each group were treated with intrathecal infusion of PDTC (100 or 1000 pmol/d) or saline. The sciatic nerve chronic constriction injury (CCI) model was used to induce NP in rats. Mechanical stimuli and radiant heat were used to evaluate mechanical allodynia and thermal hyperalgesia. Spinal microglial marker OX42 and TNF-a were detected by immunohistochemistry. In vitro BV-2 microglia activation was induced by TNF-a incubation, and the levels of CX3CR1 were assessed by Western blot and reverse transcription-polymerase chain reaction. Pain behavior and immunohistochemistry results showed that intrathecal infusion of PDTC at 100 or 1000 pmol/d prevented the development of mechanical and thermal hyperalgesia, spinal microglial activation and TNF-a expression induced by sciatic nerve CCI in rats. In vitro experiment results showed that PDTC inhibited the TNF-a-induced CX3CR1 up-regulation in BV-2 microglial cells. In conclusion, intrathecal infusion of PDTC could attenuate the pain-related behaviors induced by sciatic nerve CCI through suppressing the spinal microglia activation and TNF-a up-regulation in rats. The NF-κB activation might be responsible for TNF-a-induced CX3CR1 up-regulation in microglia.

MeSH terms

  • Animals
  • CX3C Chemokine Receptor 1 / metabolism
  • Male
  • Mice
  • Microglia / drug effects*
  • Neuralgia / drug therapy*
  • Phosphorylation / drug effects
  • Pyrrolidines / therapeutic use*
  • Rats
  • Rats, Sprague-Dawley
  • Sciatic Nerve / injuries
  • Signal Transduction / drug effects*
  • Spinal Cord / pathology
  • Thiocarbamates / therapeutic use*
  • Transcription Factor RelA / antagonists & inhibitors*
  • Transcription Factor RelA / chemistry
  • Tumor Necrosis Factor-alpha / metabolism
  • Up-Regulation / drug effects

Substances

  • CX3C Chemokine Receptor 1
  • CX3CR1 protein, rat
  • Pyrrolidines
  • Rela protein, rat
  • Thiocarbamates
  • Transcription Factor RelA
  • Tumor Necrosis Factor-alpha
  • pyrrolidine dithiocarbamic acid

Grants and funding

Funding: This work was supported by grants from National Nature Science Foundation of China (81501078, 81471135 and 81370251).