Wagner Nicole, Laugks Ulrike, Heckmann Manfred, Asan Esther, Neuser Kirsa
Institute of Anatomy and Cell Biology, University of Wuerzburg, 97070, Wuerzburg, Germany.
Department of Molecular Structural Biology, Max Planck Institute of Biochemistry, D-82152, Martinsried, Germany.
J Comp Neurol. 2015 Nov 1;523(16):2457-75. doi: 10.1002/cne.23798. Epub 2015 Jun 10.
Although age-related changes in synaptic plasticity are an important focus within neuroscience, little is known about ultrastructural changes of synaptic morphology during aging. Here we report how aging affects synaptic ultrastructure by using fluorescence and electron microscopy at the adult Drosophila neuromuscular junction (NMJ) of ventral abdominal muscles. Mainly four striking morphological changes of aging NMJs were revealed. 1) Bouton size increases with proportionally rising number of active zones (AZs). 2) Synaptic vesicle density at AZs is increased in old flies. 3) Late endosomes, cisternae, and multivesicular bodies accumulate in the presynaptic terminal, and vesicles accumulate between membranes of the terminal bouton and the subsynaptic reticulum. 4) The electron-dense pre- and postsynaptic apposition is expanded in aging NMJs, which is accompanied by an expansion of the postsynaptic glutamate receptor fields. These findings suggest that aging is possibly accompanied by impaired synaptic vesicle release and recycling and a potentially compensatory expansion of AZs and postsynaptic densities.
尽管突触可塑性的年龄相关变化是神经科学的一个重要研究重点，但对于衰老过程中突触形态的超微结构变化却知之甚少。在此，我们通过荧光显微镜和电子显微镜观察成年果蝇腹侧腹肌神经肌肉接头（NMJ），报告衰老如何影响突触超微结构。主要揭示了衰老NMJ的四个显著形态学变化。1）突触小体大小增加，活性区（AZs）数量相应增加。2）老年果蝇中AZs处的突触小泡密度增加。3）晚期内体、扁平囊泡和多囊泡体在突触前终末积累，小泡在终末突触小体和突触下网状结构的膜之间积累。4）衰老的NMJ中电子致密的突触前和突触后附着区域扩大，同时伴随着突触后谷氨酸受体区域的扩大。这些发现表明，衰老可能伴随着突触小泡释放和再循环受损，以及AZs和突触后密度的潜在代偿性扩大。
