Chronic exposure to heavy alcohol and cocaine use is known to result in widespread neuronal adaptations. Some of these changes may be specific to alcohol or cocaine exposure but other changes may be more general, reflecting shared pathways in addiction. In addition, inter-individual neurobiological variation contributes to the heritability of addiction. We have previously published a global analysis of differential expression of 16,008 gene transcripts that were detected in the postmortem hippocampus of alcoholics, cocaine addicts and controls [1]. The aim of the current study was to distinguish changes in expression of gamma-aminobutyric acid (GABA) pathway genes that might be unique to alcoholics or cocaine addicts, and to identify changes common to both. Moreover, we attempted to distinguish trait and state effects for addiction in humans by identifying differences in GABAergic gene expression in alcohol naïve rats selectively bred for high (P) and low (NP) alcohol preference, a model for vulnerability to alcohol dependence. P rats have also shown evidence for addiction vulnerability to other substances including nicotine and cocaine [2].
