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. 2017 Nov 17;37(2):300–320. doi: 10.15252/embj.201796484

Figure 4. Synaptic transmission is partly restored during sustained stimulation.

Figure 4

Synaptic transmission was assessed during and immediately after sustained stimulation in autaptic excitatory munc18‐1 neurons expressing M18WT or M18Y473D.
  1. Rundown of EPSC amplitude during 100 pulses at 10 Hz. Top: example traces of the current evoked by 40‐Hz stimulation.
  2. EPSC charge during 100 pulses at 40 Hz. Top: example traces of the current evoked by 40‐Hz stimulation. Insert shows total charge transferred during entire train (M18WT: 2.63 ± 0.38 nC, n = 18; M18Y473D: 1.48 ± 0.24 nC, n = 18; t‐test with Welch correction, *P = 0.0177).
  3. Synaptic transmission was assessed before [naive (n)] and 2 s after (a) 40‐Hz stimulation. Average EPSC charge M18WT (naive: 70.9 ± 19.5 pC; after HFS: 75.4 ± 17.4 pC, n = 12, paired t‐test, P = 0.4049). Average EPSC charge M18Y473D (naive: 0.888 ± 0.342 pC, after HFS: 25.6 ± 9.3 pC, n = 9, paired t‐test, *P = 0.0271).
  4. A hypertonic sucrose solution (500 mM, 3.5 s) was applied to release the RRP before [naive (n)] or 2 s after (a) HFS (100 pulses at 40 Hz, gray box).
  5. Quantification of RRP and P ves (EPSC charge/RRP charge * 100) from (C and D). Average RRP size M18WT (naive: 1.73 ± 0.69 nC, after HFS: 1.34 ± 0.54 nC, n = 12, paired t‐test, P = 0.0557). Average RRP size M18Y473D (naive: 0.061 ± 0.019 nC, after HFS: 0.207 ± 0.050 nC, n = 9, paired t‐test, *P = 0.0246). Average P ves M18WT (naive: 7.07 ± 0.76%, after HFS: 10.6 ± 1.6%, n = 12, paired t‐test, *P = 0.0201). Average P ves M18Y473D (naive: 0.27 ± 0.22%, after HFS: 10.8 ± 2.2%, n = 9, paired t‐test, **P = 0.0012).
  6. PDBu application (1 μM) enhanced EPSC size in neurons expressing M18Y473D.
Data information: Data are presented as mean values ± s.e.m.