Preclinical Behavioral Models for Addressing Unmet Needs in Opiate Addiction

Addiction is a behavioral state characterized by loss of control over drug use and must be appreciated as a chronic relapsing, not acute, disorder. Factors that contribute to the transition from casual use of a drug to loss of control and compulsive use include positive reinforcement (e.g., euphoria, reward), negative reinforcement (e.g., self-medication, alleviation of withdrawal), and conditioned reinforcement (either positive or negative). These same factors may interact to produce relapse even after prolonged periods of abstinence. This review summarizes the current status of animal behavioral and neurobiological models which were designed to address the multiplicity of factors contributing to the addiction process. Use of these models is critical in assessing efficacy of novel treatments, in exploring the neurobiological substrates of reinforcement, dependence, and withdrawal in an effort to identify new targets for treatment intervention, and in uncovering genetic factors that predispose certain individuals to addiction.