Lack of effect of antenatal glucocorticoid therapy in the fetal baboon on cerebral cortical glucose transporter proteins

BACKGROUND: Maternal antenatal glucocorticoid therapy is used to accelerate lung maturation of immature babies at risk of preterm delivery. It acutely affects brain activity of the human fetus and reduces the immunoreactivity of neurocytoskeletal and synaptic proteins in the fetal baboon brain. These effects might be based on cerebral energy failure due to a decreased neuronal glucose uptake that has been shown in vitro. METHODS: Glucose uptake into the brain is selectively facilitated by GLUT1 expressed in the blood-brain barrier and GLUT3 expressed in the neuronal membrane. Immunohistochemical distribution of GLUT1 and GLUT3 were examined in the frontal neocortex of the fetal baboon brain at 0.73 gestation (i.e. similar to 28 weeks of human gestation) after maternal betamethasone administration, mimicking the clinical dose regimen. RESULTS: Betamethasone did not alter GLUT1 and GLUT3 immunoreactivity. CONCLUSIONS: The results suggest that inhibition of glucose uptake is not the mechanism for the cerebral effects of antenatal glucocorticoids.