脑发育不同阶段丰富环境刺激对大鼠海马突触素表达的影响

Influence of environmental enrichment at different stages of development on the expression of p38 in hippocampus of hypoxia-ischemic brain damaged rats

【目的】探讨脑发育不同阶段丰富环境刺激对缺氧缺血性脑损伤(hypoxic-ischemic brain damage,HIBD)新生鼠神经可塑性的影响及机制。【方法】7日龄SD大鼠通过结扎左侧颈总动脉,吸入8%氧氮混合气,制成HIBD模型,分为早期干预组、晚期干预组、非干预组,另设假手术组。早期干预组于脑发育关键期内,即建模后第2 d开始进行丰富环境(environmental enrichment,EE)干预。晚期干预组于脑发育关键期后,即建模后第23 d(日龄30 d)开始进行EE干预。两组干预条件一致,总干预时间为20 d。各组大鼠饲养至日龄100 d时用免疫组织化学法检测患侧海马突触素(synaptophysin,p38)的表达水平。【结果】早期干预组患侧海马p38的表达明显高于晚期干预组和非干预组(P<0.01),早期干预组与假手术组差异无显著性(P>0.05),晚期干预组p38的表达高于非干预组(P<0.05)。【结论】EE干预可增强神经可塑性。p38在海马表达的变化,可能参与了脑发育不同阶段EE对HIBD神经可塑性的影响机制。

[Objective] To explore the effects of environmental stimulation on neuronal plasticity and possible mechanisms at different stages of development of hypoxia-ischemic brain damaged （HIBD） postnatal rats. [Methods] The Sprague-Dawley （SD） rats＇ models of HIBD were established by the method of Rice. Then the rats with HIBD were divided randomly into 3 groups：early intervention group, late intervention group and non-intervention group. The sham-operation rats served as sham-operation group. Environmental enrichment intervention was administrated to the early intervention group rats for 20 day since the 2nd day after HIBD. The same intervention to the late intervention group rats since the 23rd after HIBD. On the age of 100 day, the immunohistochemieal stain was used to detect the gray values of p38 in hippocampus respectively. [Results] lmmunohistoehemical analysis showed that the expression of p38 in left-sided hippocampus of early intervention group significantly increased as compared with that of late intervention group （P〈0.01）. There was no significant difference between early intervention group and Sham group （P〉0. 05）, and the expression of p38 of late intervention group were stronger than that of non-intervention group （P〈0. 05）. [Conclusions] The neuronal plasticity of early intervention group is promoted more than that of late intervention group. The changes of p38 in their hippocampuses are possibly associated with the influence of environment on neuronal plasticity at different developmental stage of HIBD.