3-硝基丙酸致未成熟鼠脑室周围脑白质软化的神经行为学及磁共振成像变化

Behavior assessment and magnetic resonance imaging examination on premature rats with periventricular leukomalacia induced by intracerebral injection of 3-nitropropionic acid

目的通过脑内定位注射3-硝基丙酸(3-NPA)建立新生鼠脑室周围白质软化(PVL)模型,探讨远期神经行为学和磁共振成像(MRI)变化。方法新生5 d(P5)SD大鼠随机分成实验组(NPA组)与假手术组(PBS组),脑立体定位仪定位于左侧脑室上方胼胝体,分别注入等量3-NPA和PBS,造模后1、2、3、9 d灌注固定取脑,石蜡切片作HE染色;术后不同时间点观察体重、睁眼时间等生长发育情况;P29-30进行神经行为学检测,观察两组大鼠肢体肌力、随意运动、情感行为能力和学习记忆能力;P30行MRI检查。结果NPA组大鼠术后睁眼时间延迟,体重增加高于PBS组,差异有统计学意义(P<0.05);HE染色显示NPA组大鼠P6、P7、P8 NPA组注射3-NPA侧皮质下及脑室周围白质出现不同程度疏松及液化灶,P14时出现同侧脑室明显扩大,PBS组无明显变化;神经行为学检测实验组鼠肢体肌力、随意运动、情感行为能力和学习能力较假手术组减退,评分差异有统计学意义(P<0.05);P30 MRI检查显示NPA组脑内注射侧脑室周围局部有脑组织软化信号改变。结论P5大鼠脑内注射3-NPA制作的脑室周围白质软化模型,能真实地模拟在体病理改变,经神经行为学检测与临床症状相符,MRI检查可显示脑白质损伤的解剖形态学变化,作为诊断PVL的方法具有可行性。

Objective To establish the model for periventricular leukomalacia （PVL） by intracerebral injection of 3-nitropropionic acid （3-NPA） and explore realistic model for concerned studies and investigate the diagnostic method with magnetic resonance imaging （MRI） examination. Methods Sprague-Dawley rat pups of both sexes at the age of postnatal day 5 （P5） were randomized and divided into two groups： NPA group and PBS group , and they were injected the same volume of 3-NPA and PBS with a tip located at the corpus callosum above the left ventricle by stercotaxis instrument, respectively. One day （P6）, two days （P7）, three days （P8） and nine days （P14） after injection, the injections were transcardially perfused and brains vcere collected. Then sections of brains were undertaken HE staining; growth and the time of opening eyes of the rats in the two different groups were observed and compared. Neurobehavioral activity and memory tests were performed on postnatal day 29 （P29） and day 30 （P30）. MRI examination was performed on postnatal day 30 （P30）. Results More weight increase and slower opening eye time were found in the NPA group compared with PBS group （P 〈 0.05）. In the NPA group, subortical and periventricular white matter rarefaction were observed by HE staining on P6, P7 and P8, significant lateral ventricle enlargement was found on P14, while the same changes were not found in the PBS group, and no histological changes in gray matter were noted in both groups. The outcomes of neurobe- havioral tests of NPA group were much more abnormal compared with the PBS group （P 〈 0.05）. MRI examination disclosed the signal changes of brain tissue is worse in the NPA group than that of the PBS group in muscle strength of limbs, autocinesis, capability and white matter. Conclusions The model for PVL induced by intracerebral injection of 3-NPA is characterized by damage to the periventricular white matter. The model can stimulate the pathologic change factually in vivo. The neurobehavioral movement is consistent with clinical symptom. It can be used as a model to investigate some related disease. MRI examination is a feasible diagnostic method to show anatomic changes of white matter injury of the brain.