Sex-Dependent Effects of Neonatal Hyperoxia on Prefrontal Cortex Development

Premature infants often require oxygen therapy, which increases the risk of bronchopulmonary dysplasia and long-term cognitive impairment. The prefrontal cortex (PFC), essential for higher-order cognition, may be particularly vulnerable to neonatal hyperoxia, yet the cellular and molecular effects remain unclear. We exposed C57Bl/6 mouse pups to hyperoxia (85% O₂) or normoxia from postnatal days 1–14 and performed single nucleus RNA and ATAC sequencing of the PFC, complemented by oligodendrocyte progenitor cell assays and validation in mouse and human brain tissues. Hyperoxia reduced L4/5 intratelencephalic projecting glutamatergic neurons in females and mature oligodendrocytes in males, accompanied by consistent repression of myelination genes proteolipid protein 1 (Plp1) and myelin basic protein (Mbp) and altered chromatin accessibility. Oligodendrocyte transcription factor 2 (Olig2) was induced in both sexes, whereas lysine demethylase 3A (Kdm3a) activation was female specific. Hyperoxia activated Netrin-1 signaling in males and disrupted tumor protein p53 (TP53)-regulated metabolic pathways in females. Oligodendrocyte progenitor cell proliferation and differentiation were inhibited in vitro, and human bronchopulmonary dysplasia PFC samples recapitulated these core alterations. Together, these findings demonstrate that neonatal hyperoxia disrupts PFC development through sex-dependent effects on neuronal differentiation, oligodendrocyte maturation, and transcriptional regulation. Concordant mouse-human myelination deficits highlight the pathological relevance of oxygen exposure and underscore the importance of considering sex as a biological variable in preterm brain injury.