DUSP1 Promotes Microglial Polarization toward M2 Phenotype in the Medial Prefrontal Cortex of Neuropathic Pain Rats via Inhibition of MAPK Pathway.

Shifting microglial polarization from M1 toward M2 phenotype represents a promising therapeutic strategy for neuropathic pain (NP). Dual-specificity phosphatase-1 (DUSP1) is a key component in regulating anti-inflammatory response. The medial prefrontal cortex (mPFC) is implicated in emotional disorders associated with NP and constitutes a neuroanatomical substrate for exploring mechanisms underlying NP. This study aims to investigate whether DUSP1 regulates microglial M1/M2 polarization in the mPFC in a rat model of NP. Rat model of NP was established by chronic constriction injury (CCI) of the rat sciatic nerve. Lipopolysaccharide (LPS) was used to activate HAPI rat microglial cells as an in vitro inflammatory model. CCI-induced decreased pain threshold, increased cell apoptosis in mPFC, elevated pro-inflammatory M1/M2 microglia ratio, and activated MAPK signaling in the mPFC of rats. Importantly, intra-mPFC injection of DUSP1-expressing lentivirus counteracted these abnormalities. In vitro assay further confirmed that DUSP1 overexpression switched microglial M1 to M2 polarization through inhibition of MAPK signaling activation. DUSP1 switched microglial M1 to M2 polarization in the mPFC and attenuated CCI-induced NP by inhibiting the MAPK signaling.