Abstract: ObjectiveTo study the effects and mechanisms of hypoxia-ischemia (HI) on long-term learning and memory abilities and astrocytes in hippocampal formation and the efficacy of nimotop in treating hypoxic-ischemic brain damage. MethodsThe rats were subjected to right common carotid artery ligation followed by exposure to 8% oxygen at 37℃ for 2 h and then 13 rat pups received an introperitoneal injection of nimotop per day immediately following cerebral hypoxia-ischemia for 5 days. When the rats were 80-day-old, they were given test of Y-maze to determine their learning and memory abilities, and then their brain tissues were studied by immunohistochemistry for glial fibrillary acidic protein (GFAP) that marked astrocytes. ResultsThe learning and memory abilities of the HI group were lower than those of the normal control and nimotop treated group (P<0.01), nimotop significantly increased Y-maze learning abilities (P<0.05) of rats received HI, but did not affect their memory abilities. The numerical density of GFAP-positive cells in CA1 radiatum stratum of hippocampal formation were markedly higher in the HI group than those in the other two groups (P<0.01), but the others strata showed no difference. ConclusionHypoxic-ischemic brain damage cause rats to disorders of learning and memory that may be correlated with increase astrocyte in hippocampal formation which became easy to be damaged of declining regulation abilities of neurons microenvironment. Nimotop may be effective to counteract hypoxic-ischemic brain damages.

Key words: hypoxia-ischemia, learning, memory, astrocyte, nimotop, rat