MARKED INCREASE IN GLUTAMATE-ASPARTATE TRANSPORTER (GLAST GLUT-1) MESSENGER-RNA FOLLOWING TRANSIENT RETINAL ISCHEMIA/

We have demonstrated the cellular localization of glutamate-aspartate transporter (GLAST/GluT-1) mRNA in the rat retina and its induction af ter ischemia by in situ hybridization. GLAST mRNA was expressed in the inner two-thirds of the inner nuclear layer (INL) and in sparse small cells in the inner portion of the ganglion cell layer (GCL) of the ad ult rat retina. GLAST mRNA was also found in about 90% of cells in the optic nerve head where more than 90% of cells express glial fibrillar y acidic protein (GFAP) mRNA. Moreover, experimental occlusion of the central retinal artery followed by reperfusion for 48 h resulted in de generation of neurons and a marked increase in GLAST mRNA expression i n the INL. These findings suggest that GLAST may be expressed in Mulle r cells and astrocytes in the retina, and may play an important role i n regulation of extracellular glutamate concentration especially under ischemic conditions.