老龄大鼠嗅球内神经元超微结构的改变

Changes of ultrastructures of the olfactory bulb neurons from aged rats

目的:观察老龄大鼠嗅觉障碍与嗅球内神经细胞超微结构改变的关系。方法:实验于2002-04/12在承德医学院电镜室完成。选用老龄和青龄雄性Wistar大鼠各6只,老龄组鼠龄在24个月以上,青龄组鼠龄三四个月。10g/L乌拉坦1g/kg腹腔注射麻醉后开胸,升主动脉插管,混合固定液灌流固定后取嗅球,振荡切片,平板包埋,光镜下选取嗅球各层,制备超薄切片,并在电镜下对比观察。结果:老龄组嗅球6层结构分界不明显,突触小球、小球周细胞、僧帽细胞、刷细胞和颗粒细胞数量均减少。小球周细胞的胞质和细胞器少,可见空泡或同心圆小体;僧帽细胞胞体变小,局部核膜断裂,染色质外溢,线粒体不规则,电子密度增高,线粒体嵴断裂或模糊不清,脂褐素增多;刷细胞粗面内质网、核糖体减少,高尔基复合体萎缩,溶酶体、空泡增多,线粒体固缩或形成髓鞘样小体;颗粒细胞核膜模糊,异染色质边集,细胞器明显减少。结论:嗅球内突触小球和神经元细胞减少、细胞器老化可能是导致老年性嗅觉障碍的主要原因。

AIM： To observe the association between dysosmia and the alteration of neuron uhrastructure in the olfactory bulb of aged rats. METHODS： The experiment was carried out in the Laboratory of Electron Microscopy, Chengde Medical College between April and December 2002. Six aged （above 24 months） and 6 young （3-4 months） male Wistar rats were used. The rats were anesthetized by intraperitoneal injection o 10 g/L urethane （1 g/kg）, and then chest was opened, ascending aortic cannlation was performed, and then they were perfused with compound fixative, the olfactory bulb was removed, the sections were oscillated, plate was embedded, the layers of olfactory bulb were selected under light microscope and cut into uhrathin section for comparative observation under electron microscope, RESULTS： Six layers of the olfactory bulb in aging rats were unclear. The numbers of synaptic glomerulus, glomerulus pericytes, mitral cells, brush cells and granule cells all decreased. The cytoplasm and organella of glomerulus pericyte decreased, vacuole and coeenric circle body were observed, The cell body of mitral cells became small, the chromatin effusion with karyolemma disrupted partly; the mitochondria in mitral cells were irregular and its density increased, the crista mitochondriales disrupted or unclear; the lipofuscin in mitral cells increased. The rough endoplasmic reticulum and ribosome in brush cells decreased; the Golgi complex shrank; the lysoome and vacuole increased in brush cells; the mitochondria in brush cells became pyknosis or formed myelinoid body. The karyolemma of granule cells became unclear, heterochromatin marginated and organella decreased obviously. CONCLUSION： The decreasing of the synaptic glomerulus and aging of the organella maybe the main factors that cause the olfactory bulb sensation obstruction.