The role of environmental enrichment in promoting myelin formation and neural function in hypoxic-ischemic brain injury

Abstract:

Objective To explore the effects of environmental enrichment（EE） on neural function，myelin-related protein expression of periventricular white matter and hippocampus in rats with hypoxic-ischemic brain injury（HIBD）.Method Seven-day-old SD rats were randomly divided into sham surgery group，model+standard environment group（HIBD+SE group） and model + environmental enrichment group（HIBD+EE group），and the HIBD model was established with the Rice-Vannucci method. The sham surgery group and the standard environment group were raised in the standard environment without any intervention，and the environmental enrichment group was treated with enriched environment from 8 to 18 days after surgery. At day18 after the surgery，Morris water maze was used to determine the escape latency of finding the hidden platform. Western blot was used to detect the expression of UGT8，a myelination-related protein，in periventricular white matter and hippocampus，and expression of oligodendrocyte differentiation gene OLIG2. RT-qPCR was used to detect the mRNA expression levels of OLIG2、GLTP、MYRF、UGT8 in periventricular white matter and hippocampus. Immunohistochemistry was used to detect the expression levels of NeuN，and immunofluorescence was used to detect the expression of myelin basic protein（MBP） in the corpus callosum.Result At 18 days after surgery，compared with HIBD+SE group，platform crossing times of the HIBD+EE group increased（P<0.01）. The HIBD+EE group showed higher expression of UGT8 mRNA and protein in the periventricular white matter and hippocampus compared to HIBD+SE group（P<0.05）. The expression of OLIG2，GLTP，MYRF mRNA in the periventricular white matter and hippocampus increased（P<0.05），and the expression of NeuN in CA1 region was higher than that of HIBD+SE group（P<0.01），the fluorescent intensity of MBP in corpus callosum region was higher than that in standard environment group（P<0.05）.Conclusion Environmental enrichment promotes the differentiation of oligodendrocyte lineages and myelin development in neonatal rats with HIBD，and improves learning and memory ability，which may be related to up-regulating UGT8 protein expression in periventricular white matter and hippocampus and increasing the number of neuronal mature cells.