Figure 5.

Resistance to extinction in the presence of drug-paired cues and enhanced cue-induced reinstatement. (a, b) Representative raster plot showing responding during 15 sessions of cues-ON extinction after cocaine self-administration for a Drd2^loxP/loxP (a) and an autoDrd2KO (b) mouse. (c, d) Rate of earned saline infusions during cues-ON (c) or cues-OFF (d) extinction sessions after cocaine self-administration by autoDrd2KO (solid red) and Drd2^loxP/loxP littermates (open red) (n=10–10 for ON and n=10–12 for OFF). *Genotype: F(1, 18)=4.65, p=0.045. (e) Rate of earned saline infusions during cues-OFF extinction (5 last sessions) (black) and during cue-induced reinstatement session (red) for autoDrd2KO mice (solid) and littermates (open) (n=13–10). *2W-ANOVA F(1, 42)=8.09, p=0.007, Tukey's p<0.05. (f) Rate of undelivered sucrose rewards during cues-ON extinction sessions after sucrose self-administration by autoDrd2KO (solid blue) and Drd2^loxP/loxP littermates (open blue) (n=9–12). *Genotype: F(1, 13)=0.08, p=0.78. (g, h) Normalized rate of earned saline infusion or undelivered rewards (to last 3 training sessions) for Drd2^loxP/loxP (g) and autoDrd2KO (h) for cues-ON (squared symbol, cocaine in red, sucrose in blue) and cues-OFF (cocaine in red, round symbol). Data expressed as mean±SEM.