Figure 4. Metformin protected mitochondrial networks in MPP⁺-treated differentiated SH-SY5Y cells. Cells were pretreated with metformin (500 µM) for 1 h before exposure to MPP⁺ (1000 µM) for 24 h. The mitochondria were labeled with MitoTracker red-labeled probes, and the nuclei were stained with DAPI. Images were obtained using a laser scanning confocal microscope. The circled areas indicate a tubular or thread-like appearance of the mitochondria, and the arrows indicate short-rod or sphere-like appearance.