Unilateral hypoxic-ischemic injury in the neonatal rat brain evaluated by in vivo MRI: Correlation with histopathology and neuroprotection by MK- 801

RATIONALE AND OBJECTIVES. MRI was used for the in vivo evaluation of unilateral hypoxic-ischemic brain injury and the evaluation of MK-801 in the neonatal rat. METHODS. T2-weighted scans were obtained during the acute phase of HI injury and 3 months later. Histology was performed to correlate MRI signal changes with pathology. Finally, the effectiveness of MK-801 to limit brain injury was regionally assessed in vivo using T2-weighted MRI. RESULTS. Injury visualized by MRI at 72 hours after hypoxia correlated strongly with histopathologic analysis. Transient injury was identified. MK-801 significantly reduced the lesion extent at the level of the hippocampus. Patterns of unilateral versus bilateral neonatal brain injury were found to differ. CONCLUSIONS. The study demonstrates unique patterns of brain injury not seen in adult animal hypoxia-ischemia studies, and the sensitivity of the corpus callosum to hypoxia-ischemia. MK-801, although neuroprotective, did not offer any selective neuroprotective benefit.