大鼠孤束核内突触超微结构的衰老变化

Ultrastructural Aging Changes of Synapses in Rat Nucleus of Solitary Tract

在电镜下对3个月、12个月和25个月三组大鼠孤束核内侧亚核(mNTS)内突触超微结构的变化进行了定量研究。发现25个月组内mNTS神经毡中的突触密度、突触前轴突终末密度均较3个月和12个月组明显降低,含清亮囊泡伴大颗粒囊泡的突触前终末的构成比逐渐变小,而单纯含清亮囊泡的突触前终末的构成比则增大;但神经毡内线粒体密度、单个突触前轴突终末内的囊泡数、各型突触的构成比并无明显的变化。结果表明老年期大鼠mNTS内的突触有明显的衰老变化,这种衰老始于鼠龄1年以后,与该核功能的衰退有关。

Ultrastructural changes of synapses in rat medial subnucleus of the nucleus of solitary tract(mNTS)was studied quantitatively at 2,12,25 months.Densities of the synapses arid presyrnap- tic axon terminals in neuropil were significantly lower at 25 months than at 3 and 12 months.The pro- portion of synaptic axon terminals with spherical clear vesicles and large granular ones declined gradual- ly.By contrast,those with spherical clear vesicles were raised.But no significant changes existed in the density of mitochondrial profile per unit area neuropile,the number of synaptic vesicles per presynaptic axon terminal and the proportions of various types of synapses.The results indicate that changes of synapses in aged rat mNTS appear after the first postnatal year.It may be associated with functional aging of the nucleus.