Background: Acute in utero fetal hypoxia can adversely impact on the integrity of the fetal brain. A primary manifestation of hypoxic injury is cellular energy failure mediated by mitochondrial dysfunction. Creatine is a dietary metabolite that acts as a spatial and temporal energy buffer, allowing continued generation of ATP under anaerobic conditions. It is hypothesized that creatine supplementation protects the fetal brain against mitochondrial dysfunction caused by acute in utero hypoxia in late gestation by preserving mitochondrial respiration.
Methods: At 118 days of gestation (term = 147), surgically prepared singleton sheep fetuses of 29 pregnant ewes were randomly allocated to receive an intravenous infusion of either creatine (6mg/kg/h) or saline. After 13 days of infusion, fetuses were subjected to 10 minutes of severe fetal hypoxia by complete occlusion of the umbilical cord (n=8 creatine; n=8 saline). Control fetuses did not receive a hypoxic insult (n=7 creatine; n=6 saline). 72-hour post-injury, fetal brains were collected, and mitochondria freshly isolated from grey matter, white matter and the hippocampus were used for assessment of basal, complex-II mediated, ADP-linked and uncoupled respiration. Data was analysed by Two-Way ANOVA with Turkey’s multiple comparisons.
Results: In the white matter (WM) and hippocampus (HIP), complex-II mediated (WM p=0.01, HIP p=0.03), ADP-linked (WM p=0.02, HIP p=0.01) and uncoupled respiration (WM p=0.02, HIP p=0.02) were significantly reduced following UCO. To date, no differences have been observed in the grey matter, nor has creatine treatment impacted any of these outcomes.
Conclusions: Results suggest that mitochondrial respiration is adversely impacted in the fetal white matter and hippocampus by acute in utero hypoxia. Creatine supplementation did not significantly improve mitochondrial respiration, and hence the neuroprotective effect of creatine supplementation may not directly involve preservation of mitochondrial respiratory activity. Further characterisation of mitochondrial injury through gene expression and immunohistochemical analysis is now underway.