Background: Hypoxic-ischemic injury of neurons is a pathological process observed in several neurological conditions, including ischemic stroke and neonatal hypoxic-ischemic brain injury (HIBI). An optimal treatment strategy for these conditions remains elusive. The present study delved deeper into the molecular alterations occurring during the injury process in order to identify potential therapeutic targets. Methods: Oxygen-glucose deprivation/reperfusion (OGD/R) serves as an established in vitro model for the simulation of HIBI. This study utilized RNA sequencing to analyze rat primary hippocampal neurons that were subjected to either 0.5 or 2 h of OGD, followed by 0, 9, or 18 h of reperfusion. Differential expression analysis was conducted to identify genes dysregulated during OGD/R. Time-series analysis was used to identify genes exhibiting similar expression patterns over time. Additionally, functional enrichment analysis was conducted to explore their biological functions, and protein-protein interaction (PPI) network analyses were performed to identify hub genes. Quantitative real-time polymerase chain reaction (qRT-PCR) was used for validation of hub-gene expression. Results: The study included a total of 24 samples. Analysis revealed distinct transcriptomic alterations after OGD/R processes, with significant dysregulation of genes such as Txnip, Btg2, Egr1 and Egr2. In the OGD process, 76 genes, in two identified clusters, showed a consistent increase in expression; functional analysis showed involvement of inflammatory responses and signaling pathways like tumor necrosis factor (TNF), nuclear factor kappa-light-chain-enhancer of activated B cells (NF-κB), and interleukin 17 (IL-17). PPI network analysis suggested that Ccl2, Jun, Cxcl1, Ptprc, and Atf3 were potential hub genes. In the reperfusion process, 274 genes, in three clusters, showed initial upregulation followed by downregulation; functional analysis suggested association with apoptotic processes and neuronal death regulation. PPI network analysis identified Esr1, Igf-1, Edn1, Hmox1, Serpine1, and Spp1 as key hub genes. qRT-PCR validated these trends. Conclusions: The present study provides a comprehensive transcriptomic profile of an in vitro OGD/R process. Key hub genes and pathways were identified, offering potential targets for neuroprotection after hypoxic ischemia.

Background: Neonatal hypoxic-ischemic encephalopathy (HIE) is a major cause of neonatal mortality and long-term neurological impairments. Apart from therapeutic hypothermia, there are currently no effective pharmacological treatments. Microglia, as the resident immune cells of the nervous system, play a critical role in the pathogenesis and subsequent neural repair processes of HIE. However, the exact mechanisms underlying these roles remain unclear, and potential therapeutic targets for modulating microglial polarization still need to be explored. Methods: This review outlines the physiological functions of microglia in the developing brain and the role of microglial polarization in neonatal HIE. It discusses several strategies for targeting the modulation of microglial polarization and their underlying molecular mechanisms. Results: Microglial activation is one of the core pathophysiological mechanisms of neonatal HIE. During the acute phase of hypoxic-ischemic injury, microglia are typically activated to an M1 pro-inflammatory phenotype, mediating inflammatory responses and exacerbating neuronal damage. Over time, some microglia transition into the M2 phenotype, where they play a role in tissue repair and neuroprotection. The balance between pro-inflammatory and anti-inflammatory microglial phenotypes plays a crucial role in determining the prognosis of neonatal HIE. Several interventions targeting the modulation of microglial polarization, including IL-4, miRNA, and cyclic GMP-AMP synthase (cGAS), have shown promising results in animal models. However, the therapeutic mechanisms and safety of these approaches still require further investigation. Conclusions: Understanding how to effectively regulate microglial phenotype polarization to maximize neuroprotective effects and promote brain repair holds significant potential for the treatment of neonatal HIE. This could help open new therapeutic avenues and improve the prognosis of affected infants.