Early Life Supraphysiological Levels of Oxygen Exposure Permanently Impairs Hippocampal Mitochondrial Function

Area of Science:

• Neuroscience
• Mitochondrial Biology
• Developmental Biology

Background:

• Preterm infants often require prolonged oxygen therapy, which is linked to later-life cognitive dysfunction.
• Previous studies showed spatial and learning deficits in mice exposed to hyperoxia as newborns.
• Hippocampal shrinkage was observed in these mice, suggesting a neurological impact.

Purpose of the Study:

• To investigate the hypothesis that neonatal hyperoxia induces hippocampal mitochondrial dysfunction.
• To determine the long-term effects of neonatal hyperoxia on hippocampal mitochondrial function and proteomic alterations.

Main Methods:

• C57BL/6J mouse pups were exposed to 85% oxygen or room air from postnatal day 2 to 14.
• Hippocampal proteomic analysis was conducted in young adult mice (14 weeks old).
• Mitochondrial bioenergetics were measured in both neonatal (P14) and young adult mice.

Main Results:

• Hyperoxia exposure reduced mitochondrial ATP-linked oxygen consumption and increased proton leak in both neonatal and young adult mice.
• Complex I function was decreased at P14 but increased in young adult mice.
• Proteomic analysis revealed alterations in mitochondrial complexes I, III, and IV subunits following hyperoxia exposure.

Conclusions:

• Neonatal hyperoxia permanently impairs hippocampal mitochondrial function, including alterations in Complex I activity.
• These mitochondrial changes in the hippocampus may underlie cognitive deficits observed in preterm infants.
• This mechanism could also contribute to other brain disorders associated with oxidative stress.