Assessment of a proposed "three-criteria" cocaine addiction model for use in reinstatement studies with rats.

RATIONALE: Relapse is a primary obstacle in the treatment of addiction disorders, and as such, understanding this phenomenon is a major effort of clinical and preclinical studies of cocaine addiction.
OBJECTIVE: A recently developed protocol uses laboratory rats to model cocaine addiction by examining three criteria of addiction-like behaviors (persistent seeking in the absence of drug, high motivation for drug, and resistance to punishment during drug seeking) to detect subjects that possess an addiction phenotype. We closely followed this protocol in order to detect rats possessing this addiction phenotype, with the goal of utilizing this model in future studies investigating potential therapies for relapse in human cocaine addicts.
RESULTS: The majority of the rats used in this study exhibited multiple characteristics thought to be associated with addiction-like behavior in rats, including robust reinstatement to multiple stimuli and high motivation to obtain cocaine. However, no rats displayed the complete addiction phenotype as previously described, due to a complete lack of addiction-like behavior in all subjects on two of the three addiction criteria (drug seeking in the absence of drug and resistance to punishment).
CONCLUSIONS: Our data highlight the independence of behavioral aspects of a rat addiction-like phenotype and suggest that some of these behavioral criteria may be altogether absent in some rat populations. Furthermore, our results suggest a closer review and analysis of some parameters used in this protocol and its global utility.