丰富环境对新生缺氧缺血性脑损伤大鼠运动控制及海马脑源性神经营养因子和突触蛋白的影响

Effects of enriched environment on the motor control and hippocampal brain-derived neurotrophic factor and synaptophysin in newborn rats with hypoxic-ischemic brain injury

目的:探讨丰富环境对新生缺氧缺血性脑损伤大鼠运动控制功能,以及海马区脑源性神经营养因子(BDNF)、酪氨酸激酶受体B(TrkB)、突触蛋白(SYP)表达的影响。方法:SPF级孕鼠4只,分娩出健康大鼠幼仔45只,将7日龄大鼠幼仔按随机数字表法分为空白组(n=11),假手术组(n=11),剩余23只采用改良Rice法建立新生大鼠HIBD动物模型,从造模成功的模型大鼠中二次随机分为模型组(n=12),丰富环境组(n=11)。丰富环境组在造模后24h予丰富环境刺激,连续干预28d,余组不进行处理。各组大鼠于造模前、造模后7、14、21、28d进行平衡木试验,干预结束后行HE染色观察大鼠海马病理形态变化、荧光定量PCR法检测BDNF、TrkB基因表达量、Western Blot法测定SYP蛋白水平。结果:模型组HE染色下海马CA1区细胞排列紊乱呈弥漫性分布,神经元数量减少,空泡化增加,出现水肿和坏死细胞;丰富环境组HE染色下海马CA1区细胞排列紊乱情况有所改善,水肿改善明显。与空白组和假手术组相比,模型组造模后21、28d平衡木试验评分升高(P<0.05);海马BDNF、TrkB基因相对表达量明显下降(P<0.01,P<0.05);SYP蛋白表达降低(P<0.05)。与模型组相比,丰富环境组造模后21、28d平衡木试验评分明显降低(P<0.01);海马BDNF、TrkB基因相对表达量显著升高(P<0.01);SYP蛋白表达升高(P<0.05)。结论:丰富环境可改善新生缺氧缺血性脑损伤大鼠运动控制功能,其机制可能是通过上调海马BDNF、TrkB,促进SYP表达实现的。

Objective:To explore the effects of rich environment on the motor control function of newborn rats with hypoxic-ischemic brain injury,as well as brain-derived neurotrophic factor(BDNF),tyrosine kinase B(TrkB),and synaptic protein(SYP)in the hippocampus.Method:Four SPF pregnant rats and 45 healthy rat pups were delivered.The 7-day-old rat pups were divided into blank group(n=11)and sham operation group(n=11)according to the random number table.The remaining 23 HIBD animal models of newborn rats were established by the modified Rice method,and the successfully modeled rats were randomly divided into a model group(n=12)and an enriched environment group(n=11).The enriched environment group was given enriched environment stimulation 24 hours after the model was established,and continued for 28 days,while the rest of the group was not treated.The rats in each group were subjected to balance beam test before modeling and 7,14,21,and 28 days after modeling.After the intervention,HE staining was performed to observe the pathological changes of rat hippocampus.BDNF and TrkB gene expression were detected by fluorescence quantitative PCR.Western Blot method was used to determine the level of SYP protein.Result:The cell arrangement disorder in the hippocampus CA1 area of the model group was diffusely distributed under HE staining,the number of neurons was reduced,vacuolation increased,and edema and necrotic cells appeared;the cell arrangement disorder in the hippocampus CA1 area of the rich environment group was improved by HE staining,and edema improved.Compared with the blank group and the sham operation group,the balance beam test scores of the model group increased at 21 and 28 days after modeling(P<0.05);the relative expression of hippocampal BDNF and TrkB genes decreased(P<0.01,P<0.05);The expression of SYP protein was reduced(P<0.05).Compared with the model group,the scores of the balance beam test in the rich environment group were significantly reduced at 21 and 28 days after modeling(P<0.01);the relative expression of hippocampal BDNF and TrkB genes was significantly increased(P<0.01);the expression of SYP protein was increased(P<0.05).Conclusion:Enriched environment can improve the motor control function of neonatal rats with hypoxic-ischemic brain injury.The mechanism may be up-regulating hippocampal BDNF and TrkB and promoting the expression of SYP.