Long-term effect of hypoxic-ischemic brain damage on learning and memory capacity of neonatal rats

【Objective】To evaluate the long-term effects and mechanism of hypoxic-ischemic brain damage(HIBD) on learning and memory capacity by HIBD model of neonatal rats.【Methods】7-day-old rats(n=90) were randomly divided into three groups:control group,sham-operation group and HIBD group and further separated into 6 h,24 h,72 h,7 d and 42 d groups.The animal models were established according to Rice's method.The change of neural behavior was observed in all groups.HE and TUNEL stain were employed to study the morphologic change and apoptosis cells in CA1 and CA3 region of hippocampus at the time of 6 h,24 h,72 h,7 d after HIBD The ability of learing and memory tested in 42 d group through Morris water maze.【Results】The swollen neuron and disorder arrangement in left-side of hippocampus in HIBD group were observed after 6 h.Degeneration and necrosis were observed after 24 h,especially apparent after 72 h.Lamellar necrosis was found after 7 days.The apoptosis cells appeared after 6 h in HIBD group and lasted for 7 days.The learing and memory ability in HIBD group significantly decreasuo compared with the control group.【Conclusions】The decrease of long-term learing and memory capacity in the HIBD rats may relate to the apoptosis of hippocampal cell.