File:Lu Nicoll 2009 FIG2.jpg

Figure 2.

Synaptic Physiology and Morphology of CA1 Pyramidal Neurons without AMPARs (A) Confocal images (left, low magnification; right, high magnification of the boxed area in left) show mosaic expression of Cre-GFP in the CA1 region of a typical hippocampal acute slice made from a triple-GRIAXfl/fl mouse at P25 injected at P0 with rAAV-Cre-GFP. Scale bar, left, 0.2 mm; right, 20 μm. (B) Scatter plots show amplitudes of EPSCs for single pairs (open circles) and mean ± SEM (filled circles), respectively. The scatter plots represented the data recorded from acute slices (P22–P30) infected with rAAV-CRE-GFP at P0. Distributions of EPSC amplitudes show a virtual elimination of AMPAR EPSCs (B1, Control [Cnt], −127.1 ± 26.6 pA; Cre, −3.1 ± 1.0 pA; n = 13; ∗p < 0.001) but no change in NMDAR EPSCs (B2, control, 32.0 ± 5.1 pA; Cre, 34.7 ± 8.0 pA, n = 13; p = 0.73). (Inset in B1) Sample traces are as follows: black, control cell; green, Cre cell. (B3) Bar graph shows average AMPAR (top) and NMDAR (bottom) EPSCs presented in (B1 and B2). (C) Traces of glutamate-evoked currents from OOPs in control (black) and Cre cells (green). Bar graph shows that deletion of GluA1, -A2, and -A3 eliminated the AMPAR-mediated current (Cnt, −648.7 ± 45.2 pA; n = 23; Cre, −1.0 ± 0.7 pA; n = 8; ∗p < 0.001). Scale bar, 200 pA, 1 s. (D) Bar graph shows the decay time constant of NMDAR EPSCs recorded in NBQX at +40 mV (Cnt, 0.24 ± 0.01 s, n = 22; Cre, 0.23 ± 0.01 s, n = 24; p > 0.05). Scale bar, 0.5 s. (E) (E1 and E2) Ifenprodil (3 μM) depressed NMDAR EPSCs recorded at +40 mV in Cnt and Cre cells to a similar extent. (E2) Traces of NMDAR EPSCs from the two groups of cells before and 30 min after ifenprodil application were shown on the right. Bar graph shows the average percentage of NMDAR EPSCs remaining after ifenprodil application (Cnt, 66.8% ± 3.7%, n = 4; Cre, 74% ± 4.8%, n = 5; p > 0.05). Scale bar, 50 pA, 0.1 s. (F) I/Vs of synaptic NMDARs. NMDAR EPSCs were recorded at various holding potentials (−80, −60, −40, −20, 0, +20, and +40 mV) with 4 mM Mg2+. Junction potentials have been corrected. (G) Representative confocal stacks from Cnt and Cre cells. Bar graph in right shows average number of dendritic branchpoints and dendritic length (Cnt, n = 10; Cre, n = 8; p > 0.05). Scale bar, 20 μm. (H) Representative confocal stacks of 20 μm secondary apical dendrites from Cnt and Cre cells. Bar graph in right shows average spine density (Cnt, n = 11; Cre, n = 11; p > 0.05). Scale bar, 2 μm. (A–H) The recordings and anatomy were made from acute slices (P20–P30) from animals injected at P0 with rAAV-Cre-GFP.