Decrease of phosphorylated CREB and ERK in nucleus accumbens is associated with the incubation of heroin seeking induced by cues after withdrawal.

cAMP response element binding protein (CREB) signaling is involved in the heroin reward, but whether the CREB signaling is involved in the incubation of heroin-seeking remains unknown. Here we aim to explore the expression of p-CREB and the p-ERK, an upstream molecular of CREB, in the nucleus accumbens (NAc) in the incubation of heroin-seeking induced by cue after withdrawal. First, rats were trained to self-administer heroin for 14 days, and then assessed heroin-seeking induced by context cue (CC)or by conditioned cues (CS)after 1 or 14 d withdrawal. We found that the active responses induced by CC or CS was higher after 14 d withdrawal than that after 1 d withdrawal, and the extent increased was more significant by CS than that by CC. Meanwhile, the expression of p-ERK decreased significantly when rats exposed to the CS, and decreased more after 14 d withdrawal. In contrast, reduction of the expression of p-CREB was more obvious with exposure to CS after 14 d withdrawal. Furthermore, microinjection of rolipram into the NAc decreased the heroin-seeking behavior induced by CS after 14 d withdrawal, which was correlated to an enhancement in the expression of p-CREB in the NAc. These findings suggest that the inactivation of CREB and ERK may be involved in the incubation of heroin-seeking induced by cues after prolonged withdrawal.