Abstract: Objective To compare different ischemic methods for establishing a reliable neonatal rat model for periventricular leukomalacia (PVL) which is expected to be similar to PVL in human preterm infants pathologically. Methods Two-old-day neonatal rats were randomly divided into bilateral common carotid artery ligation group，unilateral common carotid artery ligation group, and sham group.The weighing, cerebral pathological assessments under either light or electronic microscopes were respectively undertaken 2 days and 21 days after operation. Results The body weights in bilateral common carotid artery ligation group was reduced significantly compared to those in either unilateral common carotid artery ligation group or sham group (P＜0.05 for all). The relatively intact cortex but obvious pathological change of white matter in 2 days after operation and the cystic, loose, and necrotic white matter in 21 days after operation were observed under light microscope in bilateral common carotid arteries ligation group，while a diffuse neuronal injuries in cortex with a basic normal white matter was found in unilateral common carotid artery ligation group. There was significant difference in patho-logical score of white matter injury on day 21 after operation (X²=8.751, P=0.003). The myelination under electronic microscope reduced remarkably in bilateral common carotid arteries ligation group.Conclusions The ligation of the unilateral common carotid artery can induce cortical damage and the ligation of the bilateral common carotid arteries can result in white matter injury principally, and suggesting the ligation of the bilateral common carotid arteries is a reliable method for establishment of PVL model.

Key words: Periventricular leukomalacia(PVL), Model, Ischemic method, Neonatal rat