外源性谷氨酸致新生鼠脑兴奋毒性神经变性的形态学研究

Morphological study on excitotoxic neurodegeneration of exogenous glutamate in newborn rat brain

目的 :探讨外源性谷氨酸对新生鼠脑细胞的兴奋毒性作用。方法 :新生 7天SD大鼠 ,背部皮下注射单钠谷氨酸 (MSG) 2mg/ g ,在 2h、6～ 8h、2 4～ 2 8h分别光镜和电镜观察脑细胞的形态改变。结果 :光镜下 ,2h未见明显异常 ,此后可见多处脑细胞肿胀 ,进而细胞固缩。电镜着重观察海马神经元 ,变化一为神经元胞体和树突巨大膨胀 ,伴随着内质网膜的空泡化及线粒体由最早期的浓缩到巨大膨胀 ,轴突基本正常 ,核染色质由簇状集聚于核膜下呈钟面排列到向中央积聚成轮廓不规则的团块 ;变化二为胞浆和胞核均浓缩 ,胞奖中有大小不等的空泡。结论 :外源性谷氨酸能引起未成熟脑细胞的死亡 ,为某些食品添加剂对儿童脑细胞的影响的相关研究提供一定的形态学基础。

Objective:To explore the excitotoxic action of exogenous glutamate on the newborn rat brain cells.Methods:The morphological changes of brain cells in the 7-day-old SD rats were observed with light and electron microscope 2 h,6-8 h,24-28 h after treated with monosodium L-glutamate (MSG) subcutaneously.Results:The cell edema in several brain regions was observed by light microscopy.Under electron microscopy there were 2 type changes of neurons in the hippocampus.The first excitotoxic cell death process was massive swelling of neuronal dendrites and cell bodies accompanied with changes in cytoplasmic organelles,including vacuolation of endoplasmic reticular membranes,initial condensation followed by massive swelling of mitochondria.The nuclear chromatin changes begining with the formation of small clumps of chromatin in a marginal clodkface pattern,finally coalescing into central chromatin masses with irregular contour.The second excitotoxic cell death process was progressive condensation of both the cytoplasm and nucleus with vacuoles in cytoplasm.Conclusion:The exogenous glutamate can cause neuron death in the immature brain.This provide a morphological base for the relevant study on the effect of some food additives on the children brain cells.