Insulin-responsive glucose transporters-GLUT8 and GLUT4 are expressed in the developing mammalian brain

We investigated the spatial and temporal distribution of insulin-responsive facilitative glucose transporter isoforms GLUT4 and GLUT8 in the developing mouse brain. Employing Western blot analysis and specific antibodies, GLUT4 and GLUT8 peaked during the suckling phase. Immunohistochemical analysis revealed the presence of GLUT4 mainly in neurites in sensory and motor areas of cortical and subcortical structures of the brain from P7 until adulthood. In contrast, GLUT8 was found in the same anatomical structures within neurites and cell bodies. Most striking was the presence of GLUT8 in the cell bodies of the substantia nigra. We conclude that both GLUT4 and GLUT8 are present in murine brain, with highest concentrations noted during the suckling phase. These insulin-responsive isoforms may have a unique role in augmenting substrate delivery under conditions of increased demand.