伽玛刀照射培养的海马神经元形态结构的变化

Morphologic changes of hippocampal neurons irradiated with Gamma knife

目的研究伽玛刀对体外培养的海马神经元的早期放射生物学反应。方法采用不同剂量的伽玛刀射线对细胞照射后进行相差显微镜和电镜观察。结果相差显微镜下可见受损的细胞呈退行性改变，表现为胞体肿胀，折光性减弱、消失；胞浆颗粒变性，突起增粗、断裂。扫描电镜显示胞体肿胀、体积增大、细胞表面皱褶消失、甚至胞膜破裂；细胞间网络稀疏，突起增粗、断裂。透射电镜显示，胞核异形，核膜内陷；线粒体肿胀、固缩，核糖体、神经微丝解聚，胞浆空泡样变。结论伽玛刀对体外培养的海马神经元的作用不同于正常脑组织，照射早期就能表现出明显的剂量效应关系。

Objective To study the early radiobiological response of Gamma knife to the cultured hippocampal neurons in vitro. Methods The light and electron microscopy were used to see the Gamma knife irradiated neurons of rat . Results Degenerated neurons showed swelling and refrangibility weakening or disappear ance of soma, pelletlike changes of cytoplasm, thickening and breaking of processes under phasecontrast inverted microscopy. Lesions with swelling of soma and fold vanish on cell surface, enlargement of volume and rapture of membrane, the sparse of network among the cells, thickening and breaking of processes were observated under scanning electron microscopy. The ultrastructure of the insulted neurons showed irregular nuclei and concavity of nucleus membrane, a lot of swelling or condensation of mitochondria, separation of ribosome and neurofilament, and vacuolated changes of cytoplasm. Conclusions The effect on Gamma knife irradiated neurons is similar to that of normal brain tissues. There is a doseresponse relationship at early stage. The study indicates that lowdose irradiation can cause damage to cells. 