Fig. 4

The reversal of rotenone-induced DA neuron toxicity is associated with the mitochondria transfer from astrocytes to DA neurons. a-b Astrocyte was plated on cell culture inserts (fitted with 1.0 μM or 0.4 μm filters) for co-cultures to either allow or prevent access of astrocyte-derived mitochondria to DA neurons (The filtration membranes of pore size 1.0 μm allowed whereas 0.4 μm excluded the released mitochondria to pass into the co-culture media). Co-cultures with 1.0 μm filters increased the cell viability of DA neurons following rotenone (a), while the protective role was eliminated when the mitochondria were prevented to go into the media by the 0.4 μm filters (d). b, e The intracellular ATP of DA neurons showed similar trends. The intraneuronal ATP levels fell significantly (~ 50%) after rotenone (N + rot), which were significantly elevated after co-culture with astrocytes seeded on cell culture insert with 1.0 μm filters (b). In contrast, there was no recovery of intraneuronal ATP levels in the co-culture system containing a cell culture insert with a 0.4 μm filter (e). c, f Similar changes were observed with the real-time oxygen consumption rate (OCR) analysis. The OCR in rotenone-neurons was decreased, indicating a reduction in neuronal respiration and mitochondrial function, which was recovered in the co-culture system containing the 1.0 μm filters allowing mitochondria transfer. Results were presented as mean ± SEM of the triplicate assay in each experiment. Three independent experiments (N = 3). * P < 0.05, *** P < 0.001, and ^#P < 0.05