Fig. 9.

Effect of phosphatase inhibitors on synapsin I phosphorylation in stage V neurons. A, Embryonic hippocampal neurons at 7 DIV were exposed for 10 min to KRH in the absence or presence of either OA (O.A.; 500 nm) or norokadaone (Nok; 500 nm). In the stimulated samples (KCl), 55 mm KCl was present during the last minute of the incubation. The samples were then fixed and processed for double immunofluorescence with anti-synapsin (Syn; left panels) and phosphospecific anti-synapsin I (P-syn I; right panels) antibodies. Scale bar, 10 μm. B, The percentage of phosphosynapsin I-positive boutons (mean ± SD) was calculated for all of the samples in A (n = 260–280,gray bars). In phosphosynapsin I-positive boutons, the average fluorescence intensity ratio between the signals for phosphosynapsin I and for total synapsins was also calculated (white bars).