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. 2015 Jan 7;35(1):308–315. doi: 10.1523/JNEUROSCI.1944-14.2015

Figure 4.

Figure 4.

Proteasome activity was required for FMRP downregulation and the induction of prolonged epileptiform discharges in glutamate-exposed slices. A, Summary data of the effect of glutamate exposure on FMRP levels in the absence (ACSF) and presence (MG-132) of a proteasome inhibitor, MG-132 (1 μm). In the presence of MG-132, FMRP levels remained stable (MG-132, empty column) and were not altered by glutamate exposure (MG-132, filled column). Representative Western Blots are shown on the right. Ba, In the presence of MG-132 (gray bar), bicuculline perfusion after glutamate exposure elicited short epileptiform discharges (Bic 10 min) with durations that remained stable with extended perfusion (Bic 40 min). Bb, MG-132 was applied after prolonged epileptiform discharges were induced in glutamate-exposed slices by bicuculline (Bic 40 min). Addition of MG-132 had little effect on ongoing prolonged epileptiform discharges (Bic 90 min). C, Summary data of the effects of mGluR antagonists (LY + MPEP), anisomycin (aniso), and MG-132 (MG-132) on the induction of prolonged epileptiform discharges in glutamate-exposed slices. There were no significant differences in initial short epileptiform discharges among mGluR antagonists, anisomycin, or MG-132-treated slices (at Bic 10 min: in control, 427 ± 40 ms, n = 11; in LY + MPEP, 396 ± 34 ms, n = 8; in anisomycin, 418 ± 32 ms, n = 8; in MG-132, 452 ± 44 ms, n = 8; one-way ANOVA, p = 0.80). With further bicuculline perfusion, prolonged epileptiform discharges were elicited only in the control group but not in the mGluR antagonist or MG-132 groups (at Bic 40 min: in control, 4474 ± 394 ms, n = 11; in LY + MPEP, 427 ± 33 ms, n = 8; in anisomycin, 411 ± 23 ms, n = 8; in MG-132, 422 ± 49 ms, n = 8; one-way ANOVA, p < 0.001). D, Summary data showing the effects of mGluR antagonists, anisomycin, and MG-132 on ongoing prolonged epileptiform discharges. Addition of LY367385 and MPEP effectively suppressed the occurrence of prolonged epileptiform discharges (LY + MPEP: control, 4681 ± 440 ms; after drug, 452 ± 51 ms; n = 6; p < 0.001). However, addition of anisomycin or MG-132 afterward had little effects on prolonged epileptiform discharges (anisomycin: control, 4553 ± 301 ms; after drug, 4240 ± 429 ms, n = 6; p = 0.56; MG-132: control, 4485 ± 495 ms; after drug, 4587 ± 435 ms, n = 6; p = 0.89).