Diabetes, Vol 42, Issue 10 1487-1496, Copyright © 1993 by American Diabetes Association
Effect of maternal diabetes on the expression of genes regulating fetal brain glucose uptake
RE Schroeder, UP Devaskar, SE Trail, DE Demello, DP Cole and SU Devaskar
Department of Pediatrics, St. Louis University School of Medicine, Missouri.
Diabetes alters adult brain glucose uptake and glucose transporter 1 gene
expression. To investigate the effect of diabetes on genes regulating fetal
brain glucose uptake, we examined the effect of moderate (blood glucose
10-16.7 mM, normoinsulinemia) and severe (blood glucose > 16.8 mM,
hypoinsulinemia) maternal diabetes on the expression of genes regulating
fetal brain glucose uptake in the genetically nonobese diabetic mouse. In
the moderately diabetic state, a 50% decline in fetal brain GLUT1 mRNA
levels was associated with a 20% increase in the corresponding GLUT1
protein levels. Simultaneously, although fetal brain GLUT3 mRNA and protein
levels were barely detectable, no change in hexokinase I enzyme mRNA,
protein (115,000 and 100,000 M(r)) or activity, was noted. In the severe
form of maternal diabetes GLUT1 protein was unchanged, GLUT3 protein levels
remained low, and a 2- to 3-fold increase in the lower molecular form of
the hexokinase I protein (100,000 M(r)) and enzyme activity occurred. These
observations suggest that moderate and severe forms of maternal diabetes do
not affect the fetal brain glucose transporter levels to a physiologically
significant extent. The severe form of maternal diabetes, however, enhances
1.5- to 3-fold the expression and activity of hexokinase I. This enzyme
mediates the rate-limiting step in brain glucose metabolism, namely the
intracellular conversion of glucose to glucose-6-phosphate.