# Targeting APE1/Ref-1 to alleviate formalin-induced pain and spinal neuro-inflammation in rats: a promising therapeutic approach

## TL;DR

This study explores how inhibiting APE1/Ref-1 with E3330 may reduce pain and inflammation in rats, possibly through effects on dopamine signaling.

## Contribution

The study introduces E3330 as a potential therapeutic agent for inflammatory pain by modulating APE1/Ref-1 and dopaminergic pathways.

## Key findings

- E3330 improved pain thresholds and reduced inflammatory markers in formalin-induced pain in rats.
- E3330 treatment preserved APE1/Ref-1 levels and improved mitochondrial organization.
- E3330 altered dopamine receptor expression and possibly interacts with dopamine receptor sites.

## Abstract

Pain is a multifaceted condition intricately linked to inflammation, which plays a critical role in its onset and progression.

To investigate the influence of APE1/Ref-1 on oxidative stress and inflammatory marker expression, we employed a hind paw sensitization model induced by formalin. We inhibited the redox function of APE1 using E3330 and assessed its effects on pain behavior. Mitochondrial morphology was examined via electron microscopy, and the impact on dopaminergic signaling alongside bioinformatics analyses to explore potential E3330 binding to dopamine receptors.

Administration of E3330 in formalin-induced rats resulted in improved pain thresholds, as evidenced by behavioral assessments. Notably, E3330 treatment maintained normal APE1/Ref-1 levels and promoted a more organized mitochondrial structure. Administration of E3330 correlated with increased dopamine levels, a decrease in the mRNA expression of dopamine receptors DRD1 and DRD5, and a restoration of DRD2 expression in the ipsilateral spinal cords. Moreover, E3330 administration significantly reduced the expression of key inflammatory mediators including inflammasome markers. Our bioinformatics analysis using Molecular Operating Environment software indicated that E3330 possibly interacts with critical active sites within specific dopamine receptor pocket as preliminary results.

These findings suggest that E3330 may modulate pain signaling pathways from the periphery to the spinal cord, offering a novel approach for the management of inflammatory pain conditions, potentially through the modulation of the dopaminergic signaling pathway. Further research is warranted to elucidate E3330’s role in regulating central nervous system pain signal transmission, as it emerges as a promising therapeutic candidate in clinical contexts.