The Mechanical Sensitivity of Vesicle Dynamics in In Vivo and In Vitro Neurons

Axonal tension exists in neurons and may be involved in neuronal signaling. We study the effect of mechanical strain on the dynamics of vesicles in in vivo Drosophila motor neurons and in vitro Aplysia neurons. Neurons are stretched or compressed while observing vesicle dynamics by high-resolution live-imaging. In response to mechanical stretch we observe the dynamic accumulation of synaptic vesicles at the in vivo neuromuscular junction (NMJ) after approximately 50 min. Vesicle accumulation at the NMJ persists for at least 30 min after stretch is removed. In response to compression we observe disruption of vesicle dynamics in in vitro growth cones. Range and processivity of vesicle motion decrease immediately after applied compression and do not recover for at least 20 min after compression is removed. Through live-imaging this study shows that mechanical stretch promotes vesicle clustering in in vivo synapses, and compression impedes vesicle transport in in vitro growth cones.