In the magnitude of depression induced by the treatments applied at later stages suggests that time-dependent unspecific factors could affect results when transmission was monitored for long times. In this set of experiments, we compared the effects of treatments that were applied at two different times during recording. Therefore, we designed a different experimental procedure to verify if there is occlusion or not. This time we concurrently recorded the effect of a specific treatment on two slices that were either transiently pre-incubated with the complementary drug or exposed to ACSF solution Mitomycin C changes mimicking pre-incubation and drug washout. A double recording chamber allowed simultaneous measuring of field potentials in two slices belonging to different groups. This design has the advantage of avoiding differences in the timing of drug application. Moreover, slices from test and control groups came from the same animal and were subjected to the same drug application during recordings, allowing pair comparison. Summary plots for these experiments are shown in Fig. 5. The facilitation of CN depression in Ca2+ -free conditions may be related to the uptake mechanisms of cell-penetrating peptides. In parallel with endocytocis, CPP can directly penetrate through the plasma membrane. This transiently disturbs membranes but a repair response activated by local Ca2+ influx reseals them in seconds. In regular conditions uptake of ant peptide by this pathway is negligible, but it is enhanced upon lowering extracellular Ca2+. It is thus possible that the increased depression observed in low Ca2+ conditions could be due to higher peptide uptake. A main conclusion of these experiments is that Ca2+ signaling is not required for CN-depression to occur, consistent with synaptic activity-independence. Several studies highlight the importance of protein synthesis and degradation in synaptic plasticity processes. While changes in protein metabolism are not involved in expression of NMDARLTD, the situation is different for mGluR-LTD. This type of synaptic depression requires rapid protein synthesis in the dendrites and it is also regulated by Talampanel proteasome-mediated protein degradation. Our experiments showed, however, that CN-induced depression does not require and is
