Autoradiographic analysis of the regional distribution of Glut3 glucose transporters in the rat brain.

Glut3 is a glucose transporter protein which facilitates the transport of glucose across the neuronal membranes. The local distribution of Glut3 in the brain is not well known. The present study had the aim to verify the local distribution of Glut3 in the brain and to compare it with the local glucose utilization. A polyclonal antibody directed against the C-terminal peptide sequence of Glut3 was applied to cryosections of rat brains. A secondary antibody was added which had been coupled to 35S. Using autoradiography and radioactive standards, 17 cerebral structures were investigated. The results show moderate differences of Glut3 density in the structures investigated ranging from -23% to +41% of the mean density. The pineal gland was an exception with a density 66% lower than mean. Local cerebral glucose utilization (LCGU) was analyzed in identical brain structures by application of the quantitative autoradiographic 2-deoxyglucose method to conscious rats. The range of LCGU was from -59% to +55% of the mean. No correlation was found between the moderately heterogeneous Glut3 transporter density and the strongly heterogeneous local cerebral glucose utilization. The results show that the local density of Glut3 glucose transporter protein does not reflect the local level of glucose utilization in the brain.