UDP-糖、GDNF和美金胺改善新生大鼠缺血性脑白质病变的光电镜病理评估

Effect of single or combined application of UDP-glucose, GDNF and memantine on improvement of white matter injury in neonatal rats assessed with light and electron microscopy pathologically

摘要:

目的：通过光镜和电镜下脑病理研究，评估单用或联用UDP-糖、胶质细胞源性神经营养因子（GDNF）和美金胺对缺血型脑室周围白质软化（PVL）新生大鼠脑白质病变的改善效果。方法：一侧颈总动脉结扎伴缺氧2 h，建立5日龄新生大鼠PVL模型，随机分为假手术（Sham）组、PVL组、UDP-糖组（PVL后即刻腹腔注射UDP-糖2000 mg/kg）、GDNF组（PVL后即刻脑内注射GDNF 100 μg/kg）、美金胺组（PVL后即刻腹腔注射美金胺20 mg/kg）以及三联药组（PVL后即刻联用UDP-糖、GDNF和美金胺），每组各30只。每组大鼠分别于造模后7 d及21 d断头取脑，电镜下观察髓鞘形成情况，计算髓鞘数目及厚度；光镜下对脑白质病变进行病理分级及评分。结果：造模后7 d及21 d电镜结果显示，PVL组大鼠罕见髓鞘形成，排列松散，髓鞘壁明显变薄，髓鞘数量及厚度均明显少于Sham组、UDP-糖组、GDNF组、美金胺组及三联药组（P<0.01）。光镜下脑白质病理分级结果显示，PVL组大鼠在造模后7 d和21 d，其脑白质均呈轻度病变（38%~50%）或重度病变（50%~62%）。4个用药组大鼠在造模后7 d和21 d有50%~88%呈正常脑白质，呈重度病变的比例为13%~25%。病理评分显示，PVL组在造模后7 d及21 d的病理评分最高，显著高于其他5组（P<0.05）。结论：单用或联用UDP-糖、GDNF和美金胺可明显改善PVL大鼠脑白质病变。推测良好的改善作用与这些药物能促进脑内源性的神经再生及改善脑微环境密切相关。

Abstract:

OBJECTIVE: To evaluate pathologically the effect of the single or combined application of UDP-glucose, GDNF and memantine on the improvement of white matter injury in neonatal rats with periventricular leukomalacia (PVL) under light and electron microscopy. METHODS: A five-day-old neonatal rat model for PVL was established by ligation of the lateral common carotid artery following 120-minute hypoxia. Rats were randomly divided into six groups (30 rats in each group): sham-operated, PVL, UDP-glucose (UDP-glucose 2000 mg/kg intraperitoneally after PVL), GDNF (GDNF 100 μg/kg intracerebrally after PVL), tmemantine (memantine 20 mg/kg intraperitoneally after PVL), and a combination administration of three drugs (UDP-glucose, GDNF and memantine). The rats were sacrificed 7 or 21 days after PVL for assessment of pathological changes in the white matter under both light and electron microscopy. The number and thickness of the myelin sheath in the white matter were measured under electron microscopy, and both of pathological grading and scoring were undertaken under light microscopy. RESULTS: There was rare and sparse myelinogenesis with a loose arrangement of nerve fibers in the white matter under electron microscopy in the PVL group at 7 and 21 days after PVL. The number and thickness of the myelin sheath in the PVL group were significantly less than in the sham-operated, UDP-glucose, GDNF, memantine and combination administration groups (P<0.01). The results of pathological grading of white matter under light microscopy showed that all rats in the PVL group manifested either mild injury (38%-50%) or severe injury (50%-62%) at 7 and 21 days after PVL. The majority of rats (50%-88%) in the four drug administration groups had normal white matter at 7 and 21 days after PVL. The pathological scores at 7 and 21 days after PVL in the PVL group were the highest, and they were significantly higher than in the other five groups (P<0.05). CONCLUSIONS: The single or combined application of UDP-glucose, GDNF and memantine may significantly improve pathological changes in the white matter of rats with PVL. The favorable effect is inferred to be closely correlated with the improvement of brain microenvironment and the enhancement of nerve regeneration promoted by the three drugs.