Study of effect of enriched environmental inteference on neurons in hippocampus of HIBD neonatal rats

Objective To explore the possible mechanism of the recovery of hypoxic-ischemic brain damage(HIBD) and the reconstruction of the brain nervous net with early envinonmental inteference.Methods The Sprague-Dawley(SD) rat′s models of HIBD were established by the method of Rice.Then the rats were divided into 3 groups at random:normal control group,hypoxic-ischemic(HI) group and enriched environment(EE) group.The early touch and enriched environment interference were administrated to the rats since 2d after HIBD.On 28d,Morris water maze was used to evaluate the learning and memory ability,also the weight of rats were measured.The HE stain and the Nissl stain were respectively employed to observe the morphopathologic changes and the number of live neurons in the left-sided hippocampus of the rats.Results The water maze scores of EE group in place navigation test and spatial probe test were much higher than that of HI group(P0.001),there was no significant difference compared EE group with the normal control group(P0.05).The weight of EE group was much higher than that of HI group(P0.01),there was no significant difference compared EE group with normal control group(P0.05).HE stain displayed that the left-sided hippocampus of EE group was minimal abnormal with the slightly disorganized neurons and some cells lost;while the morphology of HI group was obviously abnormal with reduced cell layers;the morphology of normal control group was normal.The Nissl stain showed that the number of live neurons in the left-sided hippocampus of EE group was much more than that of HI group(P0.01).There was no significant difference compared EE group with normal control group(P0.05).Conclusion(1)The decreased neuron damage in the injured side brain tissue of HIBD neonatal rats implies that the enriched environment could protect both the neuron and the axon.(2)The neonatal rats with HIBD have disturbance with the ability of long-term learning and memory,while the enriched environmental inteference can markedly improve this ability,which indicates that early environmental inteference has great benefit to the protection of long-term learning and memory.