Influence of early intervention on learning memory ability and expression of NMDA receptor NR1 subunit protein of premature rats with brain damage

Objective To investigate the influence of early intervention on learning memory ability and expression of NR1 in premature rats with brain damage.Methods Two days old postnatal of periventricular leucomalacia(PVL) SD rats models were established by the method of SA Back.Then they were used and randomly divided into enriched environment(EE),impoverished environment(IE) and standard environment(SE) groups(n=20).The sham-operation(sham) rats were served as control group(n=20).The neonatal handling and enriched environment intervention were administrated to the EE groups.On 35d,the learning and memory function were evaluated.On 7,35d,the expression of NR1 in the hippocampus was measured by the method of immunohistochemistry.Results The learning and memory ability(escaped latent period:4.75±2.85 vs 12.45±3.23;8.42±2.23;space learning and memory test:61.36±8.12 vs 50.24±8.29,40.12±7.99)of EE group were improved compared with SE,IE group(P0.05).And those abilities of non-intervention group reduced and were much lower than those of sham group.Immunohistochemistry analysis showed that expression of NR1 on 35d in the hippocampus of EE group significantly increased compared with that of SE,IE and sham group(43.2±6.6 vs 59.5±8.1,88.5±15.5,62.3±9.5,P0.01).Conclusion Early intervention can improve learning memory ability in premature rats with brain damage.The enriched environment stimulation could increase the expression of NR1,and it may be mechanism of the recovery of PVL in the premature rats.