SIRT3 is required for the protective function of ketogenic diet on neural inflammation and neuropathic pain

Chronic neuroinflammation is a key pathological feature of neuropathic pain. The ketogenic diet (KD) has demonstrated potential to reduce neuronal excitability and alleviate inflammation in epilepsy, yet its effects and precise mechanisms in neuropathic pain remain elusive. We first observed that β-hydroxybutyrate (BHB), a key metabolite induced by KD, was reduced in mice following neuropathic pain induced by chronic constriction injury (CCI). Subsequently, we demonstrated that KD effectively alleviated CCI-induced thermal hyperalgesia and mechanical allodynia, while mitigating neuroinflammation through reduced microglial activation and pro-inflammatory cytokine levels. BHB reduced reactive oxygen species (ROS) production, which coincided with enhanced mitochondrial membrane potential in microglia, thereby attenuating microglia-mediated inflammatory responses. Both in vivo and in vitro experiments revealed KD-induced upregulation of uncoupling protein 2 (UCP2), sirtuin 3 (SIRT3) and peroxisome proliferator-activated receptor gamma coactivator 1 alpha (PGC-1α) in the spinal dorsal horn. Importantly, SIRT3 deficiency abolished KD's protective effects against neuropathic pain and reduced BHB levels, potentially attributable to diminished expression of hepatic ketone body synthases and spinal ketone body-utilizing enzymes. These findings highlight SIRT3 as a promising therapeutic target for neuropathic pain within the ketogenic diet paradigm, providing a foundation for novel therapeutic strategies.