Hypoxia-ischemia (HI) in newborns causes severe damage to the basal ganglia and life-long neurological consequences. Acute increases in extracellular glutamate and resulting excitotoxicity are possible triggers for nonapoptotic neuronal death in the striatum following HI. Deficient uptake of excitatory amino acids by neuronal and glial cell membrane glutamate transporters may contribute to this excitotoxic process. We used a piglet model of HI to test the hypothesis that subsequent striatal neurodegeneration is associated with changes in the GLAST glutamate transporter, a protein primarily expressed by astroglia. One-week-old piglets were subjected to 30 minutes of hypoxia(arterial O2 saturation 30%), followed by 7 minutes of airway occlusion(arterial O2 saturation 5%), resulting in asphyxic cardiac arrest. Cardiopulmonary resuscitation and return of spontaneous circulation were followed by recovery for 3, 6, 12, 24, 48, or 96 hours. The percentage of neurons with ischemic cytopathology in the putamen was 16%, 31%, 47%, and 79% at 3, 6, 12, and 24 hours. Immunoblot analysis revealed that the levels of mature GLAST monomers (≈65 kDa) in striatal membrane fractions were 79%, 75%, 99%, 72%, 77%, and 47% of control at 3, 6, 12, 24, 48, and 96 hours, respectively. Immunocytochemical analysis revealed no overall change in GLAST immunoreactivity density in the caudate and putamen; however, the cellular localization and intracellular compartmentalization of GLAST was altered by HI. Electron microscopic analyses demonstrated rapid and sustained subcellular damage to striatal neuron organelles, such as the rough endoplasmic reticulum and Golgi, that are crucial for the synthesis and post-translational processing of integral cell membrane proteins. These ultrastructural abnormalities were consistent with excitotoxic neuronal death. We conclude that changes in the expression and cellular localization of the GLAST glutamate transporter occur within the striatum early after HI in newborns, potentially contributing to the mechanisms for subsequent excitotoxic striatal neurodegeneration.