Effects of enriched environmental intervention on synaptic ultrastructure and synaptophysin expression in hippocampus of neonatal rats

Objective To observe the effect of early enriched environmental intervention on synaptic ultrastructure and the synaptophysin expression (p38) in hippocampal CA1 area after hypoxia-ischemic brain damage(HIBD) in neonatal rats. Methods The rat model of HIBD was made by the method of Rice in 20 Sprague-Dawley rats, and divided randomly into 2 groups: the intervention group, non-intervention group. Another 10 rats underwent sham-operation as control. From the second day after HIBD, the rats of the intervention group were kept in an enriched environment for 20 d, the rats of non-intervention group and sham-operation group were raised in standard enviroment instead. The hippocampal ultrastructure was observed with electron microscope and the p38 expression was detected immunohistochemically in all rats. Results The ultrastructure of hippocampus CA1 pyramidal neuron in the non-intervention group were distorted as compared with that in the intervention group and control group. The corrected optical densities (COD) of immunoreactive products of the hippocampal p38 were significantly decreased in non-intervention group as compared with intervention group and control group (P0.01). There were no marked difference of either ultrastructure or immunohistochemically reactived COD of p38 between intervention group and control group (P0.05). Conclusion Early enriched environment intervention could improve the synaptic reconstruction and reduce the ultrastructural damage induced by hypoxic-ischemia.