Objective     To investigate the effects of enriched environment and hydrotherapy on neonatal rats with hypoxia-ischemia brain damage.      Methods     The 7-day-old SD rats were randomly divided into intervention group (enriched environment group

hydrotherapy group

enriched environment+hydrotherapy group)

non-intervention group and sham operation group. The intervention group were treated by the methods mentioned above respectively for 28 days after HIBD. Immunohistochemical method was used to de

tect the expression of NMDA receptor NR1 subunit in hippocampal CA1 region at different time points. Behavior training (Morris water maze) for the learning and memory abilities and electron microscopy for synaptic structure were performed.      Results     The expression of NR1 in hippocampal CA1 region increased and the learning and memory abilities were improved obviously in intervention group as compared with non-intervention group

but  showed no marked difference between the enriched environment group

enriched environment+hydrotherapy group and sham group (

P

>0.05)

reduced obviously in hydrotherapy group as compared with sham group. Postsynaptic density (PSD) in hippocampus was more in intervention group than non-intervention group.      Conclusion     Enriched environment stimulus and hydrotherapy can promote the rehabilitation of neonatal rats with HIBD. The intervention effects of enriched environment and combined application of enriched environment stimulus and hydrotherapy is better than hydrotherapy. The change of NMDA receptor in hippocampus might be one of the mechanism.