Figure 5.

RGD into the NAcore during extinction training did not alter extinction or reinstated lever pressing, but acute RGD reduced cocaine-reinstated lever pressing. A, Treatment protocol for daily peptide injection, the first 8 d of extinction training, or acute peptide microinjected 10 min before an acute cocaine priming injection. B, Active lever pressing and cocaine intake were equivalent in animals receiving RAD and RGD during extinction training (see inset for average of the last 3 d of cocaine intake). C, Rats microinjected with RGD or RAD during extinction did not differ in extinction lever pressing. D, RGD during extinction (Ext) did not alter reinstated cocaine-seeking. A two-way ANOVA revealed significant differences between extinction lever pressing and lever pressing after cue (F_(1,15) = 23.53, p < 0.001) or cocaine (F_(1,15) = 6.96, p = 0.019), but no differences between RGD and RAD. ⁺p < 0.05, comparing cocaine and cue-induced reinstated lever pressing with extinction pressing using a Bonferroni post hoc test. E, Microinjection of the highest dose of RGD (10 nmol/side) reduced cocaine-induced reinstated lever pressing compared with RAD treatment (paired Student's t test, t₍₅₎ = 3.83, p = 0.012), while the lower dose (1 nmol/side) was without significant effect. *p < 0.05, comparing RAD to RGD.