Molecular and regional targets of cocaine in primate brain: liberation from prosaic views

Abstract The neurochemical processes underlying initial exposure to and reinforcing effects of cocaine are not fully understood. An enduring hypothesis of cocaine addiction is based on an underlying premise that dopamine is the acute mediator of the rewarding effects of cocaine and this nefarious role extends through each phase of addiction. Cocaine is an effective inhibitor of the dopamine transporter, thereby increasing extracellular dopamine levels. Euphoria is attributed to the cocaine-induced inundation of extracellular dopamine and the withdrawal and craving for cocaine after cessation of drug use are attributed to neuroadaptive processes to dampen dopaminergic transmission. Nevertheless, our understanding of the role of dopamine transporter blockade in cocaine addiction is not fully understood. The objectives of this laboratory are to investigate the primary targets of cocaine in the brain, those associated with the initial phase of cocaine use and that can provide leads for investigating neuroadaptive processes that may trigger addiction. Two prosaic views of the neurobiology of cocaine addiction are examined in this review. The first is based on the assumption that the dopamine transporter contributes significantly to the stimulant and reinforcing effects of cocaine, and focuses on how stimulant drugs of abuse such as cocaine bind to the dopamine transporter. We present evidence that the widespread assumption that dopamine transporter blockers require an amine nitrogen in their structure is incorrect as non-amines are effective blockers of transporters. The second prosaic view, based on the assumption that the dopamine transporter fulfills a paramount role in cocaine addiction, is assessed in view of mounting evidence that the transporter may not account for the full spectrum of cocaine's effects. Other targets of cocaine, which may be relevant to the acute and chronic effects of cocaine, are presented.