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Neonatal Hyperoxia Perturbs Neuronal Development in the Cerebellum
Till Scheuer1,2,3, Yuliya Sharkovska4,5, Victor Tarabykin5
1Department for Neonatology, Charité University Medical Center, Berlin, Germany. Till.Scheuer@charite.de.
Insights
Postnatal oxygen toxicity in newborns can damage cerebellar neurons, potentially explaining developmental issues in preterm infants. This study shows hyperoxia impairs granule and Purkinje cell development, leading to long-term neurological deficits.
Area of Science:
- Neuroscience
- Developmental Biology
- Neonatal Research
Background:
- Preterm infants often experience impaired postnatal brain development, leading to neurological deficits.
- Cerebellar maldevelopment is increasingly linked to psychomotor impairments in former preterm infants, but causes remain unclear.
Purpose of the Study:
- To investigate the effects of neonatal hyperoxia on cerebellar granule cell precursors (GCPs) and Purkinje cells (PCs).
- To define the postnatal and long-term damage caused by hyperoxia in the developing cerebellum.
Main Methods:
- Newborn rats were exposed to 80% oxygen from postnatal day 6 to 7.
- Immunohistochemistry, qPCR, and Western blots were used to assess cell proliferation, apoptosis, neuronal markers, and SHH signaling.
- Dendrite outgrowth of Purkinje cells was analyzed using immunostainings and Golgi staining.
Main Results:
- Hyperoxia decreased GCP proliferation and increased apoptosis, with downregulated neuronal markers (Pax6, Tbr2, Prox1, NeuN) observed long-term.
- Reduced Sonic hedgehog (SHH) signaling was noted, coinciding with decreased CyclinD2 and Hes1 expression.
- Granule cell injury was associated with hampered Purkinje cell maturation, including delayed dendrite formation and impaired branching.
Conclusions:
- Neonatal hyperoxia induces significant damage to cerebellar granule cells and Purkinje cells.
- This damage inhibits neuronal development and function, suggesting postnatal oxygen toxicity as a potential cause of cerebellar maldevelopment in preterm infants.
Abstract:
Impaired postnatal brain development of preterm infants often results in neurological deficits. Besides pathologies of the forebrain, maldeveolopment of the cerebellum is increasingly recognized to contribute to psychomotor impairments of many former preterm infants. However, causes are poorly defined. We used a hyperoxia model to define neonatal damage in cerebellar granule cell precursors (GCPs) and in Purkinje cells (PCs) known to be essential for interaction with GCPs during development. We exposed newborn rats to 24 h 80% O2 from age P6 to P7 to identify postnatal and long-term damage in cerebellar GCPs at age P7 after hyperoxia and also after recovery in room air thereafter until P11 and P30. We determined proliferation and apoptosis of GCPs and immature neurons by immunohistochemistry, quantified neuronal damage by qPCR and Western blots for neuronal markers, and measured dendrite outgrowth of PCs by CALB1 immunostainings and by Sholl analysis of Golgi stainings. After hyperoxia, proliferation of PAX6+ GCPs was decreased at P7, while DCX + CASP3+ cells were increased at P11. Neuronal markers Pax6, Tbr2, and Prox1 were downregulated at P11 and P30. Neuronal damage was confirmed by reduced NeuN protein expression at P30. Sonic hedgehog (SHH) was significantly decreased at P7 and P11 after hyperoxia and coincided with lower CyclinD2 and Hes1 expression at P7. The granule cell injury was accompanied by hampered PC maturation with delayed dendrite formation and impaired branching. Neonatal injury induced by hyperoxia inhibits PC functioning and impairs granule cell development. As a conclusion, maldevelopment of the cerebellar neurons found in preterm infants could be caused by postnatal oxygen toxicity.
