Fig. 3.

New PSD95-GFP puncta induced by lithium are in close apposition to neurotransmitter release sites. Fluorescence and processed images from naive (control) (A) and lithium-treated (5 mM, 4 h) (B) cells show PSD95-GFP (green) and FM4-64FX-labeled functional release sites (red) and overlapping puncta (yellow). FM4-64FX was loaded into synaptic vesicles of neurons expressing PSD95-GFP by depolarization-induced (50 mM K⁺) vesicular recycling, fixed, and then imaged with confocal microscopy. Note that FM4-64FX labels all cells in the field, whereas PSD95-GFP puncta are only present in the transfected cell. Scale bar, 10 μm.