BRAIN-DERIVED PEPTIDES REGULATE THE STEADY-STATE LEVELS AND INCREASE STABILITY OF THE BLOOD-BRAIN-BARRIER GLUT1 GLUCOSE-TRANSPORTER MESSENGER-RNA

The blood-brain barrier (BBB) GLUT1 glucose transporter gene expressio n is known to be regulated by putative brain trophic factors. Therefor e, the present study investigated the effect of a brain-derived peptid e rich preparation containing a neurotrophic factor-like action [Cereb rolysin (Cl), EBEWE, Austria]. In cultures of brain capillary endothel ial cells, Cl induced a transient increase in the abundance of BBB-GLU T1 relative to actin measured by reverse transcription-polymerase chai n reaction during the first 2 h of incubation, whereas a significant r eduction in the GLUT1 transcript was observed at 20 and 48 h. In addit ion, Cl abolished the fall in GLUT1 levels induced by actinomycin D. T he present data suggest that brain-derived factors in Cl are able to m odulate the expression of the BBB-GLUT1 gene increasing the BBB-GLUT1 transcript stability.