Celastrol Ameliorates Vincristine-induced Neuropathic Pain by Inhibiting Spinal Astrocyte Hyperactivation-mediated Inflammation, Oxidative Stress, and Apoptosis.

BACKGROUND: Neurotoxicity is the severe adverse reaction induced by chemotherapy drugs, characterized by neuropathic pain. However, there is a notable lack of therapeutic drugs for chemotherapy-induced neuropathic pain (CINP). Celastrol, a naturally occurring terpenoid active compound extracted from the roots of Tripterygium wilfordii Hook f., exhibits a neuroprotective effect, yet its therapeutic potential in CINP has not been reported. OBJECTIVE: In this study, with vincristine-induced neuropathic pain (VINP) as a model, we aimed to investigate the therapeutic effect of celastrol on VINP and its specific mechanisms. METHODS: Vincristine (VCR, 0.1 mg/kg, intraperitoneal injection) was used to induce a neuropathic pain model. Celastrol (0.5, 1.0, and 2.0 mg/kg, intraperitoneal injection) was administered to assess its therapeutic effects on VINP. Transmission electron microscopy (TEM) was employed to examine damage to the sciatic nerve fibers and mitochondria. Flow cytometry was used to detect mitochondrial membrane potential (MMP), reactive oxygen species (ROS), and cell apoptosis. Primary astrocyte cultures were utilized further to validate the therapeutic mechanisms of celastrol in VINP. RESULTS: Here, we demonstrate that celastrol inhibits VCR-induced activation of spinal astrocytes by suppressing CaMKII phosphorylation. Additionally, celastrol alleviates the Cx43-dependent inflammation caused by VCR through the inhibition of the CaMKII/NF-κB signaling pathway. Concurrently, celastrol modulates the production of reactive oxygen species (ROS) and the expression of apoptosisrelated proteins (Cleaved Caspase-3, Bax, and Bcl-2) by suppressing the phosphorylation of CaMKII in astrocytes, thereby ameliorating the mitochondrial damage and cell apoptosis caused by VCR. DISCUSSION: This study delves into the efficacy of celastrol in treating VINP and elucidates its underlying mechanisms. The findings demonstrate that celastrol elevates pain thresholds in mice, ameliorates neuropathy, and inhibits VCR-induced astrocyte activation, as well as spinal dorsal horn inflammation, oxidative stress, and apoptosis, by blocking CaMKII phosphorylation. Unlike first-line CINP drugs, celastrol targets multiple CINP-related pathological pathways. However, this study primarily focuses on male mice and lacks a naive group, which may affect the interpretation of baseline physiological parameters. Therefore, future research will incorporate female mice and naive groups to further enhance the study's comprehensiveness and reliability. CONCLUSION: Our findings reveal that celastrol exerts therapeutic effects on VINP through its antiinflammatory, antioxidant, and anti-apoptotic properties. Furthermore, we preliminarily explore the molecular mechanisms underlying these effects, thereby providing a scientific basis for celastrol as a potential therapeutic agent for CINP.