N-Acetylcysteine protects the developing brain in neonatal sepsis-like inflammation via a redox-neurovascular pathway.

BACKGROUND: Neonatal sepsis can disrupt brain development through oxidative stress, blood-brain barrier (BBB) dysfunction, peripheral leukocyte infiltration, and white matter injury. N-acetylcysteine (NAC), a glutathione precursor with antioxidant and immunomodulatory properties, is a promising neuroprotective candidate, but its effects in neonatal sepsis-like brain injury remain incompletely defined. The purpose of this study was to investigate whether early NAC pretreatment, followed by continued treatment, was associated with protection in a neonatal LPS model and examine the principal mechanisms associated with its effects.

METHODS: In this study, neonatal C57BL/6J mice received lipopolysaccharide (LPS; 3 mg/kg, subcutaneously) on postnatal day (PND) 3 to model sepsis-like injury. NAC was administered intraperitoneally 2 h before LPS (200 mg/kg), followed by daily treatment (100 mg/kg/day) through PND14. Survival was monitored to PND21. Acute outcomes at PND4 included oxidative stress, glial/inflammatory markers, MPO-positive cell accumulation, apoptosis, and BBB-related injury. Longer-term outcomes included myelination, dentate gyrus proliferation, and behavior.

RESULTS: NAC improved survival after neonatal LPS exposure, with exploratory sex-stratified analyses suggesting greater benefit in males. NAC partially restored cortical glutathione levels and reduced lipid peroxidation, indicating improved redox balance. Although it did not significantly alter galectin-3, GFAP, or NLRP3 at the time point examined, NAC reduced cortical MPO-positive cell burden and attenuated markers associated with neurovascular injury and BBB-associated pathology, including matrix metallopeptidase-9 expression and albumin extravasation. NAC also decreased apoptosis in selected brain regions and partly improved white matter-related outcomes, including oligodendrocyte precursor cell abundance, myelination, and early sensorimotor performance. However, long-term behavioral performance in the open field and novel object recognition tests was not significantly improved at PND60.

CONCLUSIONS: Overall, early NAC pretreatment followed by continued treatment mitigated neonatal LPS-induced sepsis-like brain injury and improved survival, with protection associated with restoration of redox homeostasis and reduction of MPO-positive leukocyte and markers associated with neurovascular injury and BBB-associated pathology rather than broad suppression of measured inflammatory mediators. These findings are consistent with a potential role for a redox-neurovascular-leukocyte pathway in NAC-associated neuroprotection and support further evaluation of NAC in prevention-oriented experimental paradigms relevant to high-risk preterm populations.