Cue-Elicited Reward-Seeking Requires Extracellular Signal-Regulated Kinase Activation in the Nucleus Accumbens

Presentation of a reward-paired cue results in increased ERK2 activation in the Nacc. After four training sessions, rats were presented with the tone stimulus previously paired with reward (trained-tone; n = 8) or were placed in the training context (trained-context; n = 8) with no tone or food presentations. A, Although the total number of food-cup approaches was similar in both groups of rats, rats presented with the tone made a significantly greater number of approaches during the tone compared with the pretone period. B, ERK2 activation was greater in NAcc samples taken from rats after they were presented with the tone compared with samples taken from rats that were presented with the training context (ctx) only and from control (cont) rats (white bars; n = 5). C, No effect of cue presentation on ERK2 activation was observed in samples taken from the dorsal striatum. Representative pERK and tERK Western blots are shown for each treatment group. The lower (p42) band was used for analysis. *Significantly different from pretone responding; **significantly different from control ERK activation; ^#significantly different from trained context ERK activation, all at p < 0.05. All data are represented as mean ± SEM.