Ojo Bunmi, Davies Heather, Rezaie Payam, Gabbott Paul, Colyer Francis, Kraev Igor, Stewart Michael G
Department of Life, Health and Chemical Sciences, The Open University, Walton Hall, Milton Keynes MK7 6AA, UK.
Neurosci J. 2013;2013:839535. doi: 10.1155/2013/839535. Epub 2013 Jun 24.
Advanced ageing is associated with hippocampal deterioration and mild cognitive decline. The hippocampal subregion CA3 stratum lucidum (CA3-SL) receives neuronal inputs from the giant mossy fibre boutons of the dentate gyrus, but relatively little is known about the integrity of this synaptic connection with ageing. Using serial electron microscopy and unbiased stereology, we examined age-related changes in mossy fibre synapses on CA3 thorny excrescences within the CA3-SL of young adults (4-month-old), middle-aged (12-month-old), and old-aged (28-month-old) Wistar rats. Our data show that while there is an increase in CA3 volume with ageing, there is a significant (40-45%) reduction in synaptic density within the CA3-SL of 12- and 28-month-old animals compared with 4-month-old animals. We also present preliminary data showing that the CA3 neuropil in advanced ageing was conspicuously full of lipofuscin and phagolysosome positive, activated microglial cellular processes, and altered perivascular pathology. These data suggest that synaptic density in the CA3-SL is significantly impaired in ageing, accompanied by underlying prominent ultrastructural glial and microvascular changes.
衰老与海马体退化及轻度认知衰退相关。海马体亚区CA3透明层（CA3-SL）接收来自齿状回巨大苔藓纤维终扣的神经元输入，但关于这种突触连接随衰老的完整性所知相对较少。我们使用连续电子显微镜和无偏立体学方法，研究了年轻（4个月大）、中年（12个月大）和老年（28个月大）Wistar大鼠CA3-SL内CA3棘状突起上苔藓纤维突触的年龄相关变化。我们的数据显示，虽然随着年龄增长CA3体积增加，但与4个月大的动物相比，12个月和28个月大的动物CA3-SL内的突触密度显著降低（40-45%）。我们还提供了初步数据，表明在衰老后期，CA3神经毡明显充满脂褐素且吞噬溶酶体呈阳性，有活化的小胶质细胞过程，且血管周围病理改变。这些数据表明，衰老过程中CA3-SL的突触密度显著受损，同时伴有潜在的明显超微结构胶质和微血管变化。
