Esketamine alleviates trigeminal neuralgia and anxiety-like behaviors in mice by inhibiting RIPK1/RIPK3/MLKL-mediated necroptosis

BACKGROUND: Trigeminal neuralgia (TN) is a debilitating orofacial pain condition frequently complicated by anxiety and depression, forming a self-reinforcing pain-affect cycle with limited therapeutic options. METHODS: A TN mouse model with anxiety-like behavior was established using partial infraorbital nerve transection (pIONT). Esketamine (ES) (5 or 10 mg/kg) was administered intraperitoneally from postoperative day 14 for five days. Pain thresholds, anxiety-like behaviors, and despair-like behaviors were assessed. Neuronal injury and necroptosis-related molecules in the trigeminal ganglion and hippocampus were evaluated by histology, immunofluorescence, qRT-PCR, and western blotting. A necroptosis activator was used to verify the pathway involvement. RESULTS: ES dose-dependently alleviated mechanical allodynia and anxiety-like behaviors in pIONT mice. ES treatment ameliorated neuronal damage, increased Nissl body content, and restored dendritic spine density in the hippocampal dentate gyrus region. Mechanistically, pIONT induced the significant upregulation of RIPK1, RIPK3, and MLKL at both the mRNA and protein levels in the hippocampus, with increased colocalization of RIPK3 and MLKL with NeuN-positive neurons. Administration of ES markedly suppressed these changes. Co-administration of a necroptosis activator reversed the analgesic, anxiolytic, and neuroprotective effects of ES, confirming that the therapeutic effects are mediated via inhibition of the RIPK1/RIPK3/MLKL necroptosis pathway. CONCLUSIONS: ES alleviated pain and anxiety in pIONT mice by inhibiting hippocampal necroptosis via the RIPK1/RIPK3/MLKL pathway, highlighting necroptosis as a key mechanism in TN-associated emotional disorders and supporting ES repurposing as a dual-acting therapeutic strategy.