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. 2004 Oct 28;562(Pt 1):65–72. doi: 10.1113/jphysiol.2004.077388

Figure 2. Kainate-induced changes of inward current, sIPSC and eIPSC are absent in GluR6−/− but not WT and GluR5−/− interneurones and pyramidal neurones.

Figure 2

A, in voltage clamp (Vh = −60 mV) bath application of 100 nm kainate induces an inward current in WT (−50.8 ± 9.5 pA; n = 8) and GluR5−/− (−71.4 ± 11.6 pA; n = 5), but not GluR6−/− interneurones (−1.9 ± 1.3 pA; n = 5; P = 0.002). In current clamp (interneurones held below firing threshold) bath application of 100 nm kainate leads to a depolarization and increase in firing frequency in WT interneurones (9.5 ± 2.0 mV; 3.2 ± 0.6 Hz; n = 11). Kainate-induced depolarization and increase in firing frequency are significantly bigger in GluR5−/− interneurones (16.8 ± 1.7 mV; 11.9 ± 1.4 Hz; n = 9; P < 0.02 depolarization, P < 0.0001 frequency) than in WT interneurones. Partly compromising inhibitory neurotransmission by application of 10 μm picrotoxin results in increased depolarization and firing frequency in WT interneurones (13.6 ± 1.4 mV; 11.2 ± 2.1 Hz; n = 4; P < 0.02 depolarization, P < 0.0001 frequency). B, in voltage clamp (Vh = 0 mV) bath application of 100 nm kainate (red) induces an increase in sIPSC amplitude and frequency in both WT and GluR5−/− but not GluR6−/− pyramidal neurones. Summary histogram and representative cumulative probability plots are shown. Kainate increases sIPSC amplitude and frequency in WT. In GluR5−/− sIPSC control amplitude and frequency is approximately half of WT control values. In GluR6−/− sIPSC amplitude and frequency remains unchanged by kainate at WT control levels. (n = 6 for WT and GluR5−/−, n = 5 for GluR6−/−; amplitude: P = 0.02 for WT and P < 0.09 for GluR5−/−; frequency: P < 0.1 for WT and P < 0.02 for GluR5−/−). C, paired eIPSCs show paired-pulse depression in WT and GluR6−/− but facilitation in GluR5−/− pyramidal cells in control conditions (black) as well as after application of 100 nm kainate (red). Paired pulse ratios (PPR) remain unchanged after the application of kainate. D, concomitantly, kainate (red) depresses eIPSC amplitude in WT and GluR5−/− but has no effect in GluR6−/− (n = 5 for WT and GluR6−/−, n = 4 for GluR5−/−; P < 0.0001). Figure redrawn from Fisahn et al. (2004); © Journal of Neuroscience 2004.