Long-Term Transcriptional Consequences of Drug Exposure as Cues to Understand Vulnerability to Relapse: Advances and Perspectives.

Quitting drug abuse represents a true challenge for addicted individuals because of the highly persistent vulnerability to relapse. Identifying long-lasting, drug-induced alterations in the brain-including at the transcriptome level-that underlie such vulnerability appears invaluable to improve relapse prevention. Despite substantial technological developments and research effort, however, the picture of drug-induced adaptations provided by high-throughput transcriptomics remains frustratingly partial, notably because of methodological issues. Major advances were made, however, regarding the time course and specificity of long-term transcriptional consequences of drug exposure as well as the recruitment of small, noncoding mRNAs (or miRNAs [microRNAs]) that were previously undetectable. Most importantly, high-throughput studies have benefited from systems biology approaches and shifted their interest toward regulations within functional gene networks rather than individual changes. Such network-based gene discovery approaches have proven informative to delineate the physiological processes, cellular signaling pathways, and neuronal populations altered by drug exposure. Provided the high-throughput effort will be pursued, together with the development of adapted bioinformatics tools, addiction transcriptomics should progressively integrate data across multiple scales (from epigenome to protein), allowing a better understanding of the genetics of drug abuse and opening novel therapeutic trails.