The present study was designed to evaluate 17 beta-estradiol (E2) modulation of glucose transporter 1 (GLUT-1) protein and mRNA expression in blood-brain barrier (BBB) endothelium. Female rats were ovariectomized (OVX) for 12-14 days, then E2 was injected at dosages of 1-100 micrograms/kg sc at 2-16 h before sampling. Glucose transport into BBB endothelial cells was assessed using 2-deoxy-[14C]glucose (2-[14C]DG) uptake. GLUT-1 protein and mRNA samples were analyzed by Western and Northern blotting, respectively. E2 treatment caused dose- and time-dependent increases in 2-[14C]DG uptake and GLUT-1 protein expression by microvessels. The peak responses were induced by 10 micrograms/kg E2 dose at the 4-h sampling time (36.0 and 31.3% increases, P < 0.05, respectively). GLUT-1 mRNA demonstrated a transient increase at 15 min (55%, P < 0.05), then decreased to basal level by 2 h. This study shows that in vivo treatment with E2 increases 2-[14C]DG uptake into the BBB endothelial cells and suggests this E2 effect is due to its modulation of GLUT-1 mRNA and protein.