Glycerol-3-Phosphate Attenuates Hypoxic-Ischemic Brain Injury via Modulation of Microglia-Mediated Neuroinflammation

Hypoxic-ischemic encephalopathy (HIE) is a severe perinatal brain injury that often leads to neurological impairments in survivors. Currently, effective therapeutic strategies for HIE remain limited and require further exploration. Emerging evidence indicates that microglia-mediated neuroinflammation plays a pivotal role in the pathophysiology of HIE. Nevertheless, clinically effective anti-inflammatory agents specifically targeting HIE are still lacking. Glycerol-3-phosphate (G3P) is a biologically significant metabolite involved in various cellular metabolic pathways. In this study, we investigated the neuroprotective effects of G3P against hypoxic-ischemic (HI)-induced brain injury by modulating microglial activation. In LPS-treated microglia, G3P suppressed the release of pro-inflammatory cytokines IL-6, IL-1β, and TNF-α, reduced reactive oxygen species (ROS) levels, restored mitochondrial membrane potential (MMP), and promoted a shift toward an anti-inflammatory microglial phenotype. In addition, G3P treatment in zebrafish showed no toxicity and significantly mitigated HI-induced oxidative stress, while suppressing both the recruitment and pro-inflammatory activation of mpeg1⁺ macrophages and lyzc⁺ neutrophils. Moreover, administration of G3P dramatically reduced infarct volume and alleviated neuronal loss in rats with hypoxic-ischemic brain damage (HIBD). Y-maze and Morris water maze tests demonstrated that G3P treatment significantly enhanced spatial learning and memory in HIBD rats. Furthermore, G3P markedly reduced the hyperactivation of microglia and astrocytes in both cortical and hippocampal regions. Mechanistically, Immunofluorescence and Western blot analyses revealed that G3P exerted anti-inflammatory effects by inhibiting cyclic GMP-AMP synthase -stimulator of interferon genes (cGAS-STING) signalling pathway and its downstream TBK1/the nuclear factor kappa B (NF-κB) signaling pathway. These findings highlight G3P as a promising therapeutic candidate for HIE.