FIGURE 5.

Microglia are essential for long-term depression and fractalkine restores corticostriatal synaptic plasticity in 12-week-old R6/1 mice. (A) Drawing of a mouse brain sagittal section showing the location of stimulating and recording electrodes for corticostriatal fPSC recordings (adapted from Paxinos Mouse Brain Atlas). (B) Schematic of the TBS paradigm for LTD induction. A single train of stimuli is illustrated in brackets and annotated to show the stimuli number and frequency, as well as the time scale. (C) Representative fPSC traces prior to TBS (pre-TBS, black) and after TBS (post-TBS, blue) in the six conditions of electrophysiological recordings. (D) Histograms show the quantification of fPSC amplitude in the striatum of WT and R6/1 mice relative to WT (n = 10 male mice/group), and in the presence of either 100 μM minocycline (Mino; n = 5 male mice/group) in the bath or 2 nM fractalkine (FKN; n = 5 male mice/group) in the bath, relative to absence in the bath (Ctrl). fPSC amplitude was calculated as the mean of 30 different fPSC evoked every 30 s during 15 min prior to TBS. One-factor ANOVA test; *p < 0.05 different from WT (E,F) Graphs show the time course and quantification of fPSC evoked at corticostriatal synapses and the LTD induced after a TBS (arrow) in presence or absence of either (E) 100 μM Mino in the bath (n = 5 male mice/group) or (F) 2 nM FKN in the bath (n = 5 male mice/group). fPSC amplitudes are represented as a percentage of baseline. Histograms show the mean amplitude of fPSC evoked at 29–30 min after TBS. Bonferroni’s Multiple Comparison post hoc test; *p < 0.05, **p < 0.01, different from WT-Ctrl; ^#p < 0.05 different from R6/1-Ctrl.