GLUCOSE-TRANSPORTER GLUT1 IN HUMAN BRAIN MICROVESSELS REVEALED BY ULTRASTRUCTURAL IMMUNOCYTOCHEMISTRY

The brain glucose transporter GLUT1 is a transmembrane glycoprotein be longing to the glucose carrier family comprising five isoforms charact erized by different functional properties and tissue specificity. Bioc hemical and immunohistochemical analyses have demonstrated that GLUT i soform 1 is localised within the brain microvascular endothelium, wher e it controls glucose uptake through the blood-brain barrier (BBB). In this study the expression of GLUT1 was analysed by means of light and electron immunocytochemistry in the adult human cerebellar cortex. Th e glucose transporter is strongly expressed in cerebellum microvessels , and is localised not only within endothelial cells but also in micro vascular pericytes. Moreover, some glial expression of GLUT1 was obser ved in the neuropil and in perivascular glial sheaths. The observation s demonstrate that different cellular types are involved in the contro l of brain glucose homeostasis by GLUT1 expression at the BBB site, an d support the postulated highly specialised role of brain microvascula r pericytes.