Granulocyte stimulating factor attenuates hypoxic-ischemic brain injury by inhibiting apoptosis in neonatal rats

Purpose: This study was undertaken to determine the neuroprotective effect of granulocyte stimulating factor (G-CSF) on neonatal hypoxic-ischemic brain injury. Materials and Methods: Seven-day-old male newborn rat pups were subjected to 110 minutes of 8% oxygen following a unilateral carotid artery ligation. Apoptosis was identified by performing terminal deoxynucleotidyl transferase-mediated dUTP nick end-labeling (TUNEL) staining and flow cytometry with a combination of fluorescinated annexin V and propidium iodide (PI) and JC-1 (5,5′,6,6′-tetrachloro-1,1′,3,3′- tetraethylbenzimidazolyl-carbocyanine iodide). The extent of cerebral infarction was evaluated at 2 weeks after recovery. Results: With a single dose (50 μg/kg) of G-CSF treatment immediately after hypoxic-ischemic insult, hypoxia-ischemia induced increase in TUNEL-positive cells, annexinV+/PI- and JC-1 positive apoptotic cells in the ipsilateral cerebral cortex was significantly reduced at 24 hours, measured by flow cytometry, and the extent of cerebral infarction at 2 weeks after recovery was also significantly attenuated compared to the hypoxia-ischemia control group. Conclusion: Our data suggest that G-CSF is neuroprotective by inhibiting apoptosis, thereby reducing the ensuing cerebral infarction in a newborn rat pup model of cerebral hypoxia-ischemia (HI).