Figure 10.

Synapsin IIIa accelerates synaptic depression. Time courses of synaptic depression at inhibitory synapses activated by trains of 500 stimuli applied at 10 Hz are shown. A, Depression of eIPSC amplitudes during the stimulus trains; amplitude of every tenth eIPSC is plotted. B, Mean time constant of depression in TWT and TKO neurons, as well as in TKO neurons expressing indicated synapsin isoforms. Depression was significantly faster in TKO neurons expressing synapsin IIIa. Statistical comparisons were done with ANOVA, followed by Holm–Bonferroni post hoc test; asterisks indicate significant differences (p < 0.05). C, Correlation (r² = 0.91) between rate of depression and the amount of transmitter release, as measured by eIPSC charge. Points indicate mean values ± SEM for indicated genotypes, as well as TWT neurons exposed to high (4 mm) external Ca²⁺. Sample sizes are as follows: TWT (12), TKO (10), synapsin Ia (13), synapsin Ib (11), synapsin IIa (17), synapsin IIb (10), synapsin IIIa (17), and TWT in 4 mm [Ca²⁺] (14).