https://www.selleckchem.com/products/GDC-0449.html CB1 expression was higher in sign-trackers compared with that in goal-trackers in the prelimbic cortex, but there were no significant differences in CB1 or FAAH expression in the infralimbic cortex, dorsal or ventral CA1, dorsal or ventral CA3, dorsal or ventral dentate gyrus, or amygdala. Conclusions These results demonstrate that cannabinoid signaling can specifically influence behavioral biases toward sign- or goal-tracking. Pre-existing differences in CB1 expression patterns, particularly in the prelimbic cortex, could contribute to individual differences in the tendency to attribute incentive salience to reward cues.Rationale The long-held speculation that the brain serotonin system mediates some behavioral effects of the psychostimulant cocaine is supported in part by the high affinity of cocaine for the serotonin transporter (SERT) and by reports that the serotonin transporter (SERT), estimated by SERT binding, is increased in brain of human chronic cocaine users. Excessive SERT activity and consequent synaptic serotonin deficiency might cause a behavioral (e.g., mood) abnormality in chronic users of the drug. Objective and methods Previous studies focused on changes in SERT binding, which might not necessarily reflect changes in SERT protein. Therefore, we compared levels of SERT protein, using a quantitative Western blot procedure, in autopsied brain (striatum, cerebral cortices) of chronic human cocaine users (n = 9), who all tested positive for the drug/metabolite in brain, to those in control subjects (n = 15) and, as a separate drug of abuse group, in chronic heroin users (n = 11). Results We found no significant difference in protein levels of SERT or the serotonin synthesizing enzyme tryptophan hydroxylase-2 among the control and drug abuse groups. In the cocaine users, no significant correlations were observed between SERT and brain levels of cocaine plus metabolites, or with levels of serotonin or i