Terzibasi E, Calamusa M, Novelli E, Domenici L, Strettoi E, Cellerino A
Istituto di Neuroscienze, Consiglio Nazionale delle Ricerche, Via G. Moruzzi 1, 56100 Pisa, Italy.
Neurobiol Aging. 2009 May;30(5):819-28. doi: 10.1016/j.neurobiolaging.2007.08.017. Epub 2007 Oct 24.
We have investigated morphological changes in second-order neurons of the mouse retina during aging by using immunohistochemistry and electron microscopy. We observed sprouting of rod bipolar cells dendrites and horizontal cells arborizations: neuronal processes of both neuronal types showed irregular extensions beyond the outer plexiform layer, toward the outer limiting membrane, as well as into the outer nuclear layer (ONL). These processes were first observed in animals of 12 months of age and increased in numbers steadily until 24 months, which represent the last age examined. The ectopic processes are decorated by puncta immunoreactive for pre-synaptic markers typical of photoreceptor terminals juxtaposed to post-synaptic neurotransmitter receptors, demonstrating the presence of the entire molecular machinery of functional synapses. Electron microscopy confirmed that ectopic processes receive synapses from photoreceptor terminals. We conclude that during the second year of life retinal rod bipolar and horizontal cells undergo sprouting and form ectopic synapses in the ONL.
我们通过免疫组织化学和电子显微镜研究了衰老过程中小鼠视网膜二级神经元的形态变化。我们观察到视杆双极细胞树突和水平细胞分支的发芽：这两种神经元类型的神经突都显示出不规则的延伸，超出外网状层，朝向外界膜，以及进入外核层（ONL）。这些过程首先在12个月大的动物中观察到，并持续稳定增加，直到24个月，这是所检查的最后一个年龄。异位神经突被对突触前标记物免疫反应的斑点所修饰，这些标记物是与突触后神经递质受体并列的光感受器终末所特有的，表明存在功能性突触的整个分子机制。电子显微镜证实异位神经突接受来自光感受器终末的突触。我们得出结论，在生命的第二年，视网膜视杆双极细胞和水平细胞会发生发芽，并在外核层形成异位突触。
