Genome-wide transcriptional profiling of central amygdala and orbitofrontal cortex during incubation of methamphetamine craving.

Methamphetamine (Meth) seeking progressively increases after withdrawal (incubation of Meth craving), but the transcriptional mechanisms that contribute to this incubation are unknown. Here we used RNA-sequencing to analyze transcriptional profiles associated with incubation of Meth craving in central amygdala (CeA) and orbitofrontal cortex (OFC), two brain areas previously implicated in relapse to drug seeking. We trained rats to self-administer either saline (control condition) or Meth (10 days; 9 h/day, 0.1 mg/kg/infusion). Next, we collected brain tissue from CeA and OFC on withdrawal day 2 (when Meth seeking is low and non-incubated) and on day 35 (when Meth seeking is high and incubated), for subsequent RNA-sequencing. In CeA, we identified 10-fold more differentially expressed genes (DEGs) on withdrawal day 35 than day 2. These genes were enriched for several biological processes, including protein ubiquitination and histone methylation. In OFC, we identified much fewer expression changes than in CeA, with more DEGs on withdrawal day 2 than on day 35. There was a significant overlap between upregulated genes on withdrawal day 2 and downregulated genes on withdrawal day 35 in OFC. Our analyses highlight the CeA as a key region of transcriptional regulation associated with incubation of Meth seeking. In contrast, transcriptional regulation in OFC may contribute to Meth seeking during early withdrawal. Overall, these findings provide a unique resource of gene expression data for future studies examining transcriptional mechanisms in CeA that mediate Meth seeking after prolonged withdrawal.