Biochemical Properties of

Drugs of abuse, Including nicotine, activate common pathways in the brain that lead to reinforcement and addiction. Each drug, however, has unique molecular targets. This article describes what is known about the neurobiological processes underlying the re-inforcing actions of nicotine that ultimately lead to nicotine dependence. The pathway starts with binding of nicotine to nicotinic acetylcholine receptors, its biochemical targets in the brain, which results in altered dopamine physiology and, ultimately, smoking be-havior. Experiments using genetically altered mice have begun to identify the molecules involved in this pathway. This type of experiment will ultimately allow identification of the individual molecules in the brain that carry out the steps leading to nicotine addiction and may identify sites of intervention that could lead to novel treatments for nicotine addiction