Immunogold study of regional differences in the distribution of glucose transporter (GLUT-1) in mouse brain associated with physiological and accelerated aging and scrapie infection

Distribution of glucose transporter (GLUT-1) in brain microvascular endothelia, representing the anatomic site of the blood-brain barrier (BBB), was studied in adult, physiologically aged, senescence-accelerated prone (SAMP8) and in scrapie-infected mice. Sections of tissue samples obtained from four brain regions (cerebral cortex, hippocampus, cerebellum, and olfactory bulb) and embedded in Lowicryl K4M were exposed to anti-GLUT-1 antiserum followed by gold-labeled secondary antibody. Labelling density was recorded over luminal and abluminal plasma membranes of the microvascular endothelial cells. We found that the density of immunosignals for GLUT-1 in the cerebral cortex showed a tendency toward insignificant diminution according to the following gradation-adult > SAMP8 > scrapie > aged mice-whereas in the hippocampus, this gradation was slightly different: adult > aged > scrapie > SAMP8 mice. In the cerebellum, immunolabelling was insignificantly diminished in aged mice, whereas it was significantly decreased in scrapie-infected and SAMP8 mice. The intensity of labelling of the vascular endothelium in the olfactory bulb was significantly lower than that in other brain regions, showing a slight decrease in the following sequence: adult > aged > scrapie > SAMP8 mice. These findings suggest that the process of aging as well as of related neurodegenerative disease affects unequally the distribution of GLUT-1 in the vasculature of different brain regions.