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. 2022 Dec 21;110(24):4144–4161.e7. doi: 10.1016/j.neuron.2022.09.035

Figure 7.

Figure 7

Robust PDBU sensitivity of uEPSCs in O-LM INs

(A) Confocal maximum intensity projection image of a biocytin-filled, synaptically connected PC – O-LM IN pair in the hippocampal CA1 region (top). Note the extensive axonal arbor of the O-LM IN in the stratum lacunosum moleculare (s.lm.). Bottom left: epifluorescent image of a tdTomato-positive IN, acquired prior to patching. Bottom right: DIC image of the same IN, with the patch pipette.

(B) Individual (thin traces) and the averaged (thick traces) uEPSCs evoked by three action potentials at 40 Hz are shown for the baseline (gray) and after 4-AP wash-in (red) of the recording period from the same pair (left). Superimposed averaged traces of the first uEPSCs at the beginning (black) and end (dark red) of the recording are on the top, right. The amplitude of the first uEPSCs is not significantly different at the beginning of the recording and after the application of 5 μM 4-AP (bottom right; baseline: mean of 60 traces, 0–10 min; 4-AP: mean of 60 traces, 20–30 min; p = 0.17, WSR test, n = 11 pairs in 9 mice). Presynaptic PCs were recorded in whole-cell configuration.

(C) Same as (B) but showing the effect of 1 μM PDBU on uEPSCs in O-LM cells. PDBU significantly increased the amplitude of first uEPSCs of the train (n = 9 pairs in 9 mice; p = 0.013 WSR test). Presynaptic PCs were recorded in perforated patch configuration.

(D) Same as (B) but demonstrating the effect of simultaneous application of PDBU and 4-AP (n = 12 pairs, in 11 mice, p = 0.009, WSR test). Presynaptic PCs were recorded in whole-cell configuration.

(E) Summary of the effects of different drugs on the amplitude of first uEPSCs recorded from O-LM cells and FSINs. Plots show normalized drug effects, corrected to the rundowns measured in control recordings for O-LM, but not for FSIN or for O-LM∗ (seeFigures 6B, S2A, and S2D). All data, apart from O-LM∗, were obtained with presynaptic PCs recorded in the whole-cell configuration. Data indicated with O-LM∗ were obtained with PCs recorded in the perforated patch configuration. Statistical comparison between FS and O-LM was assessed with MWU test (p = 0.007 in 4AP, p = 0.16 in PDBU [FS vs. O-LM], p = 0.024 in PDBU [FS vs. O-LM∗], p = 0.015 in 4-AP + PDBU).

Horizontal lines in the boxplots: 25th, 50th, and 75th percentiles, rectangle: mean, whiskers: SD.