Activation of PPARγ attenuates neuropathic pain by modulating spinal cuproptosis-associated mitochondrial dysfunction and neuroinflammation

Abstract

Abstract Cuproptosis is a recently identified form of programmed cell death driven by copper accumulation. Increasing evidence suggests that copper dyshomeostasis contributes to neuroinflammatory processes. Peroxisome proliferator-activated receptor gamma (PPARγ) activation has been implicated in the regulation of cuproptosis; however, its role in cuproptosis-associated neuropathic pain remains poorly understood. This study aimed to investigate whether spinal PPARγ modulates cuproptosis and thereby influences neuropathic pain in a rat model of chronic constriction injury (CCI). Neuropathic pain behaviors were assessed using mechanical and thermal sensitivity tests. Intrathecal catheterization was performed for spinal drug administration. Mitochondrial ultrastructure was examined by transmission electron microscopy. Copper concentration, protein expression, oxidative stress, mitochondrial function and inflammatory signaling were evaluated using western blotting, immunofluorescence staining, dihydroethidium staining and the enzyme activity assay kit. CCI induced a time-dependent increase in spinal copper levels, accompanied by upregulation of the copper transport-related proteins SLC31A1, ATP7A, and SCO1, and downregulation of the cuproptosis-related protein FDX1. These changes were coincided with excessive mitochondrial structural damage, ROS accumulation, reduced mitochondrial respiratory chain complex IV activity and progressive activation of the NF-κB signaling pathway. Activation of spinal PPARγ significantly alleviated CCI-induced mechanical allodynia and thermal hyperalgesia. This effect was associated with restoration of copper homeostasis, suppression of SLC31A1, ATP7A, and SCO1 expression, enhancement of FDX1 expression, improvement of mitochondrial function and inhibition of NF-κB p65 phosphorylation in the spinal cord. These findings suggest that PPARγ activation alleviates neuropathic pain by modulating copper dyshomeostasis, mitochondrial dysfunction, and neuroinflammatory signaling associated with cuproptosis. Targeting the PPARγ regulated spinal cuproptosis-associated mitochondrial dysfunction and neuroinflammation may represent a promising therapeutic strategy for neuropathic pain.