Figure 4.

A single in vivo cocaine exposure does not induce a generalized alteration of prefrontal cortex-NAc synapses. a, Single cocaine injection (n = 7) did not alter mGluR2/3-LTD [compared with sham; n = 10; 60 min after application of the selective mGluR2/3 agonist LY354740 (200 nm) for 10 min; p > 0.05]. The dashed line represents 100%. b, Single cocaine exposure did not change NAc protein levels of mGluR2/3. Densitometry measurements are expressed as percentage of control ± SEM. Single cocaine exposure (n = 4) did not alter mGluR2/3 protein levels in the NAc, compared with saline (n = 3; p > 0.05). c, Input-output curves for sham-treated mice and mice treated with a single injection of cocaine were similar. d, Left, Paired-pulse ratios were augmented after eCB-LTD induction in sham animals (1.21 ± 0.0910 min before tetanus compared with 1.36 ± 0.09 50 min after tetanus; n = 12; ^***p < 0.05 but not in cocaine-treated animals (1.17 ± 0.08 10 min before tetanus compared with 1.12 ± 0.09 50 min after tetanus; n = 20; p > 0.05). Right, Baseline paired-pulse ratios were identical in vehicle- and cocaine-treated animals [1.21 ± 0.09 (n = 12) in sham animals compared with 1.17 ± 0.08 (n = 20) in cocaine-treated animals; p > 0.05], suggesting that basal probability of transmitter release was unchanged after cocaine injection. tet, Tetanus.