Effect of maternal deprivation on learning and memory ability and hippocampal nerve regeneration in rats with hypoxic-ischemic brain damage

Objective To observe the effect of maternal deprivation(MD) on learning and memory ability and hippocampal pathology and nestin expression in rats with hypoxic-ischemic brain damage (HIBD). Methods The models of HIBD SD male rats were established by the method of Rice, and were randomly divided into 2 groups: MD group and control group.In addition, the sham-operation group(sham group) models were established.The MD group rats were separated from their mother 3 hours per day from the second day after modeling to the 21st postnatal day.After 28 postnatal days, Morris water maze was used to evaluate the learning and memory ability of the rat models.HE staining was employed to observe the hippocampal pathological change in the rats.Then, the expression of nestin in the hippocampus was measured by the method of immunohistochemistry. Results Their body mass changes showed that quality of sham group was higher than that of the control and the MD groups, and quality was improved in the control group, compared with the MD group, and the differences were statistically significant(q=9.860 8, 3.880 7, 5.980 1, all P<0.05). The water maze scores of the MD group in place navigation test and spatial probe test were much lower than that of the control group and the sham group, and the scores of the sham group were higher than that of the control group, the differences were statistically significant(all P<0.05). The findings of HE stain showed that the pathology in the right-sided hippocampus of the sham group was normal and neurons were well-arranged, and that of control group was minimally abnormal, and the neurons were almost arranged orderly and remained normal.While, the pathomorphology of the MD group was obviously abnormal, the neurons were arranged disorderly, many of the neurons lost.According to the immunohistochemical findings, the number of nestin-positive cells in right-sided hippocampus of the MD group was significantly less than that of the control group, and the number of nestin-positive cells of the sham group was less than that of the MD group, which showed significant differences among the groups(all P<0.05). Conclusions MD aggravated injury to learning and memory ability of neonatal rats with HIBD, and decrease the number of nestin-positive cells of MD markedly, which is not good for the recovery of brain injury. Key words: Hypoxic-ischemic; Maternal deprivation; Learning and memory; Pathology; Nestin