Figure 3
From: Transient ECM protease activity promotes synaptic plasticity
Inhibition of MMP-9 activity reduces the number of AMPAR-silent synapses presumably through the recruitment of AMPARs to the synapse.
(A–C) Schematic representation of the minimal stimulation protocol that was used to calculate the number of silent synapses. The graphs show 40–50 consecutive stimulation trials, resulting in either successes (gray, blue or red circles) or failures (black circles) in triggering AMPAR- and NMDAR-mediated EPSCs, recorded at −60 mV and +45 mV, respectively. (D) Summary bar graph that shows an increase in the number of silent synapses in rats that overexpressed MMP-9. Application of the MMP inhibitor GM6001 (25 μM) decreased the number of AMPAR-silent synapses. Numbers in brackets represent the number of recorded cells. (E) Example average traces of AMPA EPSCs that were recorded at −60 mV and composite AMPA and NMDA EPSCs that were recorded at +45 mV, peak-scaled to the size of the NMDA response in WT rats (shown in gray). The relative amplitude of AMPA responses decreased in MMP-9 TG animals (red) and increased upon MMP-9 inhibition with GM6001 (blue). (F) Summary bar graph that shows a decrease in the ratio of AMPA/NMDA EPSCs amplitudes in rats that overexpressed MMP-9. Application of the MMP inhibitor GM6001 increased the relative size of AMPAR-mediated currents. Numbers in brackets represent the number of recorded cells.
