Olig2 downregulation mitigates early neurological deficits by modulating mitochondrial dynamics in neonatal hypoxic-ischemic brain injury

OBJECTIVE: Mitochondrial dysfunction and apoptosis are key pathological events in neonatal hypoxic-ischemic brain damage (HIBD). Oligodendrocyte transcription factor 2 (Olig2) is upregulated during the early phase of hypoxic-ischemic brain injury. This study aimed to investigate whether Olig2 downregulation modulates mitochondrial dynamics, apoptosis-related signaling, and early neurobehavioral outcomes in neonatal HIBD. METHODS: In vivo, postnatal day 3 (P3) rats were subjected to hypoxic-ischemic injury using the Rice-Vannucci model and were intracerebroventricularly injected with adenoviral vectors carrying Olig2-targeting RNAi or a matched control sequence. Olig2 knockdown and neurobehavioral performance were evaluated at P6/P10. In vitro, HT22 cells were subjected to 3-h oxygen-glucose deprivation, followed by 24 h of reoxygenation (OGD/R). Olig2 was silenced using small interfering RNA; then, mitochondrial morphology, ATP levels, and mitochondrial and apoptosis-related proteins were assessed. RESULTS: In vivo, Olig2 expression was upregulated following hypoxic-ischemic injury, and its knockdown partially improved early neurological deficits, including righting reflex and forelimb grasp at P6, as well as righting reflex, forelimb grip, and cliff avoidance at P10. In vitro, OGD/R-induced Olig2 upregulation, while Olig2 knockdown increased mitochondrial aspect ratio and partially restored ATP levels. OGD/R also elevated dynamin-related protein 1 (Drp1) expression and reduced B-cell lymphoma 2 and optic atrophy 1 levels compared with controls. Olig2 knockdown reversed these changes while decreasing Drp1 and mitofusin 1 (Mfn1), with mitofusin 2 (Mfn2) remaining unchanged. CONCLUSION: Downregulation of Olig2 was associated with improvements in early neurobehavioral outcomes and mitochondrial function, potentially mediated through suppression of apoptosis and modulation of mitochondrial dynamics.