Abstract: To establish the models of moderate hypothermia intervention after hypoxic - ischemic brain damage (HIBD) in newborn rats,the posthypoxic - ischemic 7day -old rats,weighing 14g±2g，were divided into 4 groups. The rats in group 1～3 (i. e. Hy24 group，n=26 ;Hy48 group14；Hy72 group，n=20) were placed in water bath stabilized at 29℃ for 24h,48h .and 72h respectively and fed with formular milk at the same time,and those in group 4 (RoT group,n=44) were stayed in a breeding room (25～29℃) with dams. After the insult ,the levels of blood glucose,blood gas andplasma lactate were monitored. Two weeks after HIBD,body weight increase percents (WIP) .right brain injury scores (BIS) and percents of necrotic neurons in right hippocampus (HNNP) were determined. The results showed that the levels of blood glucose in the animals fed with formular milk for 72 h were kept at normal levels (＞3 mmol/L) ,and the brain temperatures were decreased by 4～5℃ after hypothermia intervention. At 6h after HIBD there were hypoxemia and metabolic acidosis in RoT group,but in Hy24 group all rats recovered with nearly normal levels of blood gas and plasma lactate. Two weeks after HIBD.WIP was significantly lower in RoT group than in Hy24 group (88.0% vs 134.5%，P＜0.01),and not different between Hy48 and RoT groups (P＞0.05). The results of neuropathological observation of the brains indicated that BIS and HNNP in Hy groups were significantly reduced by 53%～89% with 24h to 72h hypothermia intervention specially in Hy72 group,as compared to RoT group. The authors provided successful model of hypothermia intervention after HIBD in newborn rat by formular milk feeding,and found that the optimal effects of moderate hypothermia intervention after HIBD were reached when the intervention lasted 72h and made the brain temperature decreased by 4～5℃。

Key words: Formular milk, Moderate hypothermia intervention, Hypoxic - ischemic brain damage, Animal model, Rat