As noted above, rats permitted to self-administer cocaine during extended (≥ 6 h) but not restricted (1 h) daily session demonstrate the emergence of compulsivelike cocaine intake, including escalation of daily cocaine intake reminiscent of the increasingly uncontrolled intake seen in human addicts bingeing on the drug. Our laboratory has used miRNA gene expression arrays to characterize miRNA expression profiles in striatum of cocaine-naive rats and in rats with restricted or extended daily access to cocaine. We also assessed miRNA expression in “yoked” rats that received cocaine infusions noncontingently when rats in the extended access group volitionally consumed the drug. We found that two miRNAs, miR-212 and miR-132, were upregulated in the striatum of the extended access rats 24 hours after the last cocaine self-administration session relative to the yoked, restricted access and cocaine-naive control groups.115 We verified these findings using Taqman assay.115 These two miRNAs are arrayed in tandem in the miR-212/132 cluster located on chromosome 17 in humans and chromosome 10 in rats.116 As such, both miRNAs are thought to function similarly. Next, to investigate the potential role
