Figure 1.

NMDAR activation controls accumulation of synapsin at developing excitatory presynaptic terminals. (A, B) Immunofluorescence images of synapsin in a control neuron (A) and a neuron treated with APV to block NMDAR activation (B). Fluorescence intensity is pseudo-colored according to the indicated scale. Scale bar: 10 μm. (C) APV treatment decreases accumulation of synapsin at developing presynaptic terminals. To ensure that presynaptic puncta were synaptic, analysis was limited to synapsin puncta that overlapped with PSD95. (D) APV similarly decreased the apparent size of synapsin puncta. (E) APV did not significantly decrease the density of synapsin puncta. Data are presented as mean ± standard error of the mean, normalized to the control mean, and the number of puncta (C-D) and images (E) measured are indicated on each bar. *, significant difference (P-values are indicated in the figure). (F) Immunoblot demonstrating that overall levels of synapsin were unchanged by APV treatment. (G) Quantification of synapsin integrated density from immunoblotting. The small difference in intensity was not significant (P = 0.28).