Fig. 4.

Cleavage of Gap43 by caspase-3 is required for LTD induction. Cultured hippocampal slices (Div 6–7) were biolistically transfected with a construct expressing the visual marker Venus along with an empty vector, or constructs expressing wild-type or mutant caspase-3 substrates. At 2–3 days after transfection, LTD was induced by low-frequency stimulation of the Schaffer collateral pathway. For clear visualization of EPSC data collected from different conditions, EPSCs recorded from CA1 neurons transfected with the empty vector or wild-type Gap43 were shown in (A), those from cells transfected with the empty vector or single Gap43 mutants in (B), and those from cells transfected with the empty vector, double or quadruple Gap43 mutants in (C). D, EPSCs at 30 min after LTD induction were normalized to pre-induction baselines. Sample traces of EPSCs collected at 10 min before (1) and at 30 min after LTD induction (2) are displayed and superimposed (1 + 2) on the top of histograms in (A–C). For each condition, the EPSC amplitude, which was normalized to baseline before LTD induction, was plotted as mean ± S.E. Two-tailed Student's t test was used for statistical analysis. n = 9–10 transfected neurons for each group; *p < 0.05, **p < 0.01, compared with cells transfected with the empty vector.