FIGURE 4.

A_2AR blockade shifts reverses LTP to LTD at excitatory synapses in layer 5 FS interneurons. (A) Biocytin reconstruction of a FS interneuron from coronal slice of rat mPFC showing relative positions of recording and stimulating electrodes. (B) Voltage responses to hyperpolarizing (–80 pA) and depolarizing (+360 pA) somatic current injections to the soma of a FS interneuron. Scale bars: 20 mV, 200 ms. (C) Plasticity induction protocol. TBS was induced by stimulation of 10 bursts of five pulses each at 100 Hz, repeated three times. Scale bars: 10 mV, 200 ms. (D) After obtaining a baseline measure of EPSPs, TBS-LTP was induced. EPSPs were then recorded for up to 30 min to observe changes in EPSP slope. Slices were pre-incubated in either control ACSF (black traces) or in ACSF with added SCH58261 (100 nM; blue traces). Scale bars: 2 mV, 20 ms. Representative TBS-LTP experiments in control (E) and 100 nM SCH58261 (F) conditions showing slope and input resistance (top and bottom panels, respectively) versus time. Gray shading indicates time of TBS induction. (G) Summary plot of control (black symbols) and SCH58261 (100 nM; blue symbols) experiments, showing a robust LTP in control condition, and a strong LTD in SCH58261 pre-incubated cells. (H, left panel) The fraction of cells that obtain plasticity is reversed in control versus SCH58261 conditions. In control, 70% of cells display LTP, whereas in SCH58261, 70% of cells display LTD. (H, right panel) Summary bar chart of control and SCH58261 (100 nM) TBS-LTP experiments, showing percentage change in EPSP slope for both conditions (mean ± SEM; control: n = 10; SCH58261: n = 10). ^∗∗∗∗p < 0.0001 compared to the respective control (black dots), unpaired Student’s t-test. ^∗∗p < 0.01 compared to the hypothetical value of 100, one-sample t-test. ^∗∗∗p < 0.001 compared to the hypothetical value of 100, one-sample t-test.