Smith Heather L, Bourne Jennifer N, Cao Guan, Chirillo Michael A, Ostroff Linnaea E, Watson Deborah J, Harris Kristen M
Department of Neuroscience, Center for Learning and Memory, Institute for Neuroscience, University of Texas at Austin, Austin, United States.
Department of Cell and Developmental Biology, University of Colorado Denver - Anschutz Medical Campus, Aurora, United States.
Elife. 2016 Dec 19;5:e15275. doi: 10.7554/eLife.15275.
Mitochondria support synaptic transmission through production of ATP, sequestration of calcium, synthesis of glutamate, and other vital functions. Surprisingly, less than 50% of hippocampal CA1 presynaptic boutons contain mitochondria, raising the question of whether synapses without mitochondria can sustain changes in efficacy. To address this question, we analyzed synapses from postnatal day 15 (P15) and adult rat hippocampus that had undergone theta-burst stimulation to produce long-term potentiation (TBS-LTP) and compared them to control or no stimulation. At 30 and 120 min after TBS-LTP, vesicles were decreased only in presynaptic boutons that contained mitochondria at P15, and vesicle decrement was greatest in adult boutons containing mitochondria. Presynaptic mitochondrial cristae were widened, suggesting a sustained energy demand. Thus, mitochondrial proximity reflected enhanced vesicle mobilization well after potentiation reached asymptote, in parallel with the apparently silent addition of new dendritic spines at P15 or the silent enlargement of synapses in adults.
线粒体通过产生三磷酸腺苷（ATP）、隔离钙、合成谷氨酸以及其他重要功能来支持突触传递。令人惊讶的是，海马体CA1区不到50%的突触前终扣含有线粒体，这就提出了一个问题，即没有线粒体的突触是否能够维持效能变化。为了解决这个问题，我们分析了出生后第15天（P15）和成年大鼠海马体中经过theta爆发刺激以产生长时程增强（TBS-LTP）的突触，并将它们与对照或无刺激的突触进行比较。在TBS-LTP后30分钟和120分钟，仅在P15时含有线粒体的突触前终扣中囊泡减少，并且在成年含有线粒体的终扣中囊泡减少最为明显。突触前线粒体嵴变宽，表明能量需求持续存在。因此，在增强达到稳定状态后很长时间，线粒体的接近程度反映了囊泡动员的增强，这与P15时新树突棘的明显沉默添加或成年时突触的沉默扩大并行。
