GLUT1 and GLUT3 mRNAs in normal and post-ischemic gerbil brains were examined qualitatively and semi-quantitatively using in situ hybridization in conjunction with image analysis. Coronal brain sections at the level of the anterior hippocampus were prepared three hours, one day, and three days after animals were subjected to six min of ischemia. The sections were hybridized with vector- and PCR-generated RNA probes labeled with 35S. Microscopic evaluation of hybridized brain sections coated with autoradiographic emulsion indicated that GLUT1 mRNA was associated with brain microvessels, choroid plexus, and some ependymal cells. GLUT1 mRNA was not observed in neurons, except that one day following ischemia, this mRNA was induced in neurons of the dentate gyrus. GLUT3 mRNA was detected only in neurons. Image analysis of film autoradiograms revealed that both the GLUT1 and GLUT3 messages increased following ischemia but returned nearly to control levels by day three. In the CA1 region of the hippocampus the increase in GLUT3 mRNA was not statistically significant, and by day three the level had fallen significantly below the control, coinciding with the degeneration of the CA1 neurons. Our results suggest that the brain possesses mechanisms for induction and up-regulation of glucose transporter gene expression.