Baicalin targets AMPKα1 to alleviate microglial inflammation by increasing the protein stability of HDAC1 in hypoxic–ischemic encephalopathy

Background Hypoxic–ischemic encephalopathy (HIE) is a serious neonatal neurological disorder in which microglia-mediated acute neuroinflammation serves as a critical driver of disease progression. Our previous work revealed that H3K9 lactylation-driven microglial M1 polarization promotes neuroinflammation as a key mechanism in HIE. Baicalin, a natural compound isolated from the traditional Chinese herb Scutellaria baicalensis , is well known for its anti-inflammatory effect, but whether it can treat HIE through this anti-inflammatory effect remains unclear. Purpose This study aimed to determine whether baicalin can inhibit H3K9 lactylation-mediated microglial M1 polarization and neuroinflammation in HIE. Methods In vivo, an HIE rat model was established in which rats were treated with intraperitoneal injections of baicalin. In vitro, an oxygen‒glucose deprivation model was constructed using BV2 microglia. Network pharmacology and molecular docking were employed to predict and validate the potential targets of baicalin, after which functional assays were performed. Co-immunoprecipitation combined with mass spectrometry was further used to explore the underlying molecular mechanisms. Results Through network pharmacology analysis, molecular docking and validation experiments, we revealed that baicalin exerts its anti-inflammatory effects via the activation of adenosine 5′-monophosphate-activated protein kinase α subunit 1 (AMPKα1). Further co-immunoprecipitation and mass spectrometry analyses revealed that AMPKα1 activation promotes the phosphorylation of histone deacetylase 1 (HDAC1), a key delactylase, thus inhibiting the degradation of HDAC1 mediated by the E3 ligase ubiquitin protein ligase E3A (UBE3A). Finally, baicalin increases HDAC1 protein levels to inhibit H3K9 lactylation-mediated microglial M1 polarization via targeting AMPKα1. Conclusion These findings suggest that, when administered at an early stage after HIE, baicalin may contribute to the attenuation of HIE pathology, at least in part by increasing HDAC1 stability through AMPKα1- and UBE3A-mediated “phosphorylation–ubiquitination hierarchical regulation”, thereby reducing H3K9 lactylation and suppressing microglial M1 polarization. Download: Download high-res image (186KB) Download: Download full-size image