Text Box: MODEST HYPOTHERMIA PROVENTS APOPTOSIS IN A NEONATAL RAT MODEL OF HYPOXIC-ISCHEMIC BRAIN DAMAGE Guo Y-L, Li R-L Department of Pediatrics, Second Hospital of Xi’an Jiao Tong University, Xi’an, China Objective: Recent studies in neonatal animals have shown that even slightly decreasing in brain or core temperature could ameliorate the damage resulting from hypoxic-ischemia insults. But the influence of hypothermia which had been used after the end of hypoxia-ischemia of the model hypoxia-ischemia brain damage (HIBD) was unknown. This research wanted to investigate whether hypothermia of defferent begin time after HIBD still can protect the brain in neonatal rats. Methods: Pericranial temperatures were adjusted to 31℃ in neonatal rats immediately or 2 h after the end of hypoxia-ischemia (HI), the number of apoptosis cells in HIBD rats’ brain had been counted, rat pups’ storing food ability had been observed. Results:Apoptosis increased obviously when rat pups were 8 days old, hypothermia reduced apoptosis when rat pups were 8 days old, and postponed apoptosis expression in group that 31℃ hypothermia was used immediately or 1 h after the end of HI, and hypothermia improved the rat pups’ storing food ability. This effect was more obviously in the group that hypothermia was used immediately after the end of HI than in the group that hypothermia was used 1 h after the end of HI. But the protective effect was not clear in the group that hypothermia was used 2 h after the end of HI. Conclusion: Hypothermia which was used within 1 h after the end of HI could protect the HIBD neonatal rat pups’ brain, this effect was more obviously in the hypothermia be used early after the end of HI group than in the hypothermia be used late after the end of HI group. 1126