The deposition of beta-amyloid (Aβ) in the brain is detected in Alzheimer’s disease and during ageing. Until now, ultrastructural studies of changes caused by Aβ in the dentate gyrus are very scarce. The effects of Aβ 1-42 injection into the CA1 field of rat hippocampus were studied by electron microscopy. In 2 weeks after injection of aggregated Aβ in low concentrations, destructive changes were seen in the structure of dentate gyrus cells, which consisted in a decrease in the number of dentate gyrus neurons and axo-dendritic synapses. These changes were accompanied by enlargement of the endoplasmic reticulum cisterns and widening of the active zones of synapses. Thus, injection of aggregated Aβ 1-42 into the hippocampus led to irreversible (a decrease in the number of neurons and axo-dendritic synapses, agglutination of synthetic vesicles) and adaptive changes (an increase in the sizes of endoplasmic reticulum cisterns and active zones of synapses) in dentate gyrus neurons aimed at the maintenance of functional activity of the nervous system.

中文翻译：

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海马内注射 β-淀粉样蛋白 1-42 引起齿状筋膜颗粒神经元的超微结构改变

β-淀粉样蛋白 (Aβ) 在大脑中的沉积可在阿尔茨海默病和衰老过程中检测到。到目前为止，关于齿状回中 Aβ 引起的变化的超微结构研究非常少。通过电子显微镜研究了Aβ 1-42 注射到大鼠海马CA1区的影响。在注射低浓度聚集的 Aβ 2 周后，齿状回细胞的结构出现破坏性变化，包括齿状回神经元和轴突-树突触的数量减少。这些变化伴随着内质网池的扩大和突触活动区的扩大。因此，将聚集的 Aβ 1-42 注射到海马中会导致不可逆转的（神经元和轴突-树突突触的数量减少，