Hydrogen-Rich Water Enhances Ibuprofen-Induced Antinociception and Modulates NOX Signaling and the NLRP3 Inflammasome in Chronic Inflammatory Pain

Chronic inflammatory pain is sustained by persistent oxidative stress and inflammatory signaling that promote peripheral and central sensitization. Although nonsteroidal anti-inflammatory drugs (NSAIDs), including ibuprofen, remain first-line therapies, their long-term use is limited by dose-dependent adverse effects. Therefore, strategies capable of enhancing NSAID efficacy while maintaining an acceptable safety profile are of considerable therapeutic interest. In this study, we investigated whether hydrogen-rich water (HRW) enhances the antinociceptive effects of ibuprofen in male C57BL/6J mice with complete Freund’s adjuvant (CFA)-induced chronic inflammatory pain. Dose–response studies demonstrated that both HRW and ibuprofen significantly attenuated mechanical allodynia and thermal hyperalgesia. Notably, co-administration of a low dose of HRW with ibuprofen produced significantly greater antiallodynic and antihyperalgesic effects than either treatment alone. Molecular analyses further showed that the combined treatment reduced the paw expression of the oxidative stress marker 4-hydroxynonenal (4-HNE) and the inflammasome component NLRP3, as well as spinal NADPH oxidases (NOX), NOX1 and NOX4 expression, while maintaining the CFA-induced upregulation of heme oxygenase-1 (HO-1) and superoxide dismutase-1 (SOD-1) protein levels. In contrast, spinal NOX2 expression remained unchanged. These findings indicate that the enhanced antinociceptive effect of HRW plus ibuprofen is associated with coordinated modulation of oxidative stress and inflammatory pathways at peripheral and/or spinal levels. Collectively, our results support HRW as a promising adjuvant strategy for improving NSAID-mediated analgesia and provide a strong preclinical rationale for further mechanistic and translational investigation of this combination as a multimodal therapeutic approach for chronic inflammatory pain.