The aim of this study of GABAergic gene expression in postmortem hippocampal samples was to distinguish changes that were common to both addictions as well as changes that might be unique to alcoholics or cocaine addicts. Many of these gene expression changes are likely to reflect tolerance to chronic, heavy use but it is possible that some differences between dependent individuals and controls may represent risk factors for addiction. Therefore we attempted to gain insight into trait versus state effects by comparing gene expression changes in alcoholics and cocaine addicts versus controls with gene expression changes in alcohol-naïve P and NP rats that were selectively bred for extremes of alcohol consumption behavior and are considered to be a realistic animal model of human alcohol dependence [25], [26], [30], [31]. P rats also show addiction vulnerability to other substances including cocaine [2].
