下颌后缩对大鼠脑血流及脑卒中恢复的影响

The effect of mandibular retrusion on cerebral blood flow and stroke recovery in rats

目的探究下颌后缩对脑部血流的改变以及对脑卒中恢复产生的影响和潜在的机制。方法6周龄的SD雄性大鼠选作实验对象。金属套管粘接于大鼠上颌切牙1周,迫使下颌后缩(MR)。通过激光散斑成像检测MR对脑部血流改变;莫里斯水迷宫检测MR对认知功能改变。而后通过大脑中动脉阻塞法(MCAO)对MR建造脑卒中模型(MCAO MR)观察1周。此外,将MCAO MR大鼠在制备MCAO当天去除金属套管,使其在自然状态下恢复下颌骨的位置,设为脑卒中+咬合恢复(MCAO RO)组并作为阳性对照。至此将大鼠分为Sham组、MCAO组、MCAO MR组、MCAO RO组。通过改良神经评分检测神经功能;2,3,5-氯化三苯基四氮唑(TTC)染色检测大鼠大脑缺血面积;苏木精-伊红(HE)染色观察神经细胞变化;免疫组化检测血管内皮生长因子(VEGF)蛋白表达水平;Western blot检测血小板-内皮细胞黏附分子(CD31)、沉默调节蛋白6(SIRT6)、硫氧还蛋白互作蛋白(TXNIP)的蛋白表达水平,qRT-PCR检测SIRT6、TXNIP、VEGF的mRNA表达水平;免疫荧光检测小胶质细胞活化标志物离子钙结合衔接分子1(IBA-1)。结果激光散斑显示下颌后缩使脑部血流出现降低,水迷宫显示认知功能下降。MCAO MR相较于其他组,TTC染色显示的缺血面积更大,HE染色和神经评分显示神经系统功能恢复更差。Western blot和qRT-PCR显示MCAO MR组抑制SIRT6的mRNA和蛋白表达水平,上调了TXNIP的mRNA和蛋白表达水平,小胶质细胞活化增多。结论下颌后缩降低脑部血流改变大鼠认知功能,并调控SIRT6/TXNIP轴抑制脑卒中大鼠血流和神经恢复。

Objective To explore the changes in cerebral blood flow caused by mandibular retrusion,as well as the impact and potential mechanisms on stroke recovery.Methods 6-week-old SD male rats were selected as experimental subjects.The metal cannula was bonded to the rat maxillary incisor for one week,forcing mandibular retrusion(MR).Cerebral blood flow was detected by laser speckle imaging.Cognitive function was detected by the Morris water.Then,the stroke model was constructed in MR rats by using the middle cerebral artery occlusion(MCAO)method for one week.Meanwhile,metal cannulae were then removed in rats to restore the lower jaw′s position(MCAO RO),serving as a positive control group.Consequently,rats were randomly divided into the following groups:Sham groups,MCAO groups,MCAO MR groups,and MCAO RO groups.Neurological recovery was assessed through the modified neurological severity score(mNSS).The area of cerebral infarction was evaluated by using triphenyltetrazolium(TTC)staining.The changes in nerve cells were observed by using hematoxylin eosin(HE)staining.The protein expression level of vascular endothelial growth factor(VEGF)was detected by immunohistochemistry.The protein expression levels of platelet-endothelial cell adhesion molecule(CD31),sirtuin 6(SIRT6),and thioredoxin interaction protein(TXNIP)were detected by Western blot.The mRNA expression levels of SIRT6,TXNIP,and VEGF were determined by qRT-PCR.Microglia activation marker molecule 1(IBA-1)was detected by immunofluorescence.Resluts Because of mandibular retrusion,laser speckle showed decreased cerebral blood flow,and the water maze showed decreased cognitive function.Compared to other groups,MCAO MR showed a larger ischemic area in TTC staining,while HE staining and neurological scoring showed poorer neurological function recovery.Western blot and qRT-PCR showed that the MCAO MR group inhibited the mRNA and protein expression levels of SIRT6,upregulated the mRNA and protein expression levels of TXNIP,and increased the activation of microglia.Conclusion Mandibular retrusion reduces cerebral blood flow and alters cognitive function in rats.Mandibular retrusion inhibits recovery in stroke through the SIRT6/TXNIP axis.