【摘要】 目的 调查新生大鼠缺氧缺血脑白质和灰质损伤的组织学和磁共振 (MR)影像的变化。方法 7日龄Wistar鼠(n=24)随机分为假手术组和实验组(右 颈动脉结扎+吸入8％氧1．5 h)。在缺氧前、缺氧最后5-10分钟、缺氧后1 h和24 h行头部MR扫描获得12和表面弥散系数(ADC)。结果 1．5 h缺氧将结束时,在 缺氧缺血半球皮质下白质和顶部灰质可见ADC明显降低和T2增高;缺氧缺血后1 h,皮质下白质和顶部灰质ADC部分恢复,T2持续增高,而缺氧缺血后24 h,T2进一 步增高。与灰白质类似的MRI改变相反,组织学检查显示:缺血半球白质不可逆细 胞损伤发生早于灰质。在缺氧缺血后1 h,缺血半球皮质下白质可见神经纤维稀疏或 紊乱,并可见TUNEL阳性细胞增加,而在缺血半球顶部灰质区未见明显细胞损伤或 TUNEL阳性细胞增加,到缺氧缺血后24 h,灰白质均可见明显的损伤。结论 在目 前的新生鼠脑缺氧缺血模型,T2和ADC均能发现急性缺氧缺血脑白质和灰质水肿 或损伤,但它们不能区分白质和灰质不同的病理变化,组织学上新生鼠脑白质比灰质 更易遭受缺氧缺血损害。更多还原

【Abstract】 Objective To investigate changes of histology and magnetic resonance ( MR) imaging in the cerebral gray and white matter damage in neonatal rats following an episode of hypoxia-ischemia. Methods Seven days old Wistar rats ( n = 24 ) were subjected to either sham procedures or cerebral hypoxia-ischemia (HI, right carotid artery occlusion +8% oxygen for 1.5 h). Maps of T2 and the Apparent Diffusion Coefficient (ADC) of water were acquired prior to cerebral HI, within last 5-10 min of HI and at 1 h or 24 h after HI. Results Near the end of HI, ADC decreased and T2 increased in both parietal cortical gray and subcortical white matter of HI hemisphere. One hour after HI, ADC partially recovered but T2 remained increased and then increased further at 24 h post HI. In contrast to the similar MR responses in white and gray matter, histological evidence for irreversible cell damage occurred in white matter earlier than in gray matter within the HI hemisphere. At 1 h post HI, rarefied or disrupted nerve fibers and TUNEL-positive cells increasing were observed within subcortical white matter of HI hemisphere whereas neurons within the cortical gray matter appeared normal. By 24 h post HI, damage was apparent in both white and gray matter. Conclusions ADC and T2 can detect acute cerebral edema or damage following HI in both gray and white matter, but it can’t distinguish the early irreversible histological tissue injury in white and gray matter更多还原