Figure 4.

MPP⁺ does not affect axonal movement of synaptic vesicles. Dissociated DA/GFP cultures were transduced with Syn-Cer lentivirus at DIV2. Vesicular movement was assessed on DIV12–13 before and after toxin treatment. A, Although some vesicles were clumped and appeared to overlap mitochondria, individual vesicles labeled with Syn-Cer (arrows) were also visualized adjacent to mitochondria labeled with MTR (arrowheads). B, Vesicular movement was observed for 5 min before and after 30 min of incubation with and without 2 μm MPP⁺. Because of the smaller size of vesicular particles and the relative “dimness” of the cerulean emission, tracks of moving particles are shown below for clarity. C, D, Quantification of moving particles (C) and speed (D) were determined as described in Materials and Methods. Scale bar: 10 μm. Mean ± SEM, ns, nonsignificant, total of 25 (control) and 38 (MPP⁺-treated) axons from 4 and 5 dishes in 4 independent experiments. Total lengths of control and MPP⁺-treated axons sampled were 2247 and 3497 μm, respectively. Hatching indicates toxin treatment.