Behavioral pattern analysis and dopamine release in quinpirole-induced repetitive behavior in rats.

Obsessive-compulsive disorder (OCD) is a chronic and disabling psychiatric disease with a lifetime prevalence of 2-3%. People with OCD suffer from intrusive, unwanted and recurrent thoughts (obsessions) and/or repetitive ritualistic behaviors (compulsions). The aim of this study is to quantify the dimensions of ritualistic 'compulsive-like' behavior in quinpirole-induced behavior in rats by using T-pattern behavioral analysis. In addition, we investigated whether the behavioral effects elicited by quinpirole sensitization remained after 2 weeks of cessation of treatment. Finally, to study the neurobiological underpinnings of this 'compulsive-like' behavior, we investigated the effect of quinpirole treatment on the extracellular dopamine levels in the nucleus accumbens. Once established, 'compulsive-like' behavior is dependent upon quinpirole administration, as this behavior rapidly normalized after cessation of treatment. After a single dose of quinpirole the dopamine level decreased more in saline pre-treated animals as compared with animals given quinpirole treatment continuously. Furthermore, T-pattern analysis revealed that quinpirole-induced behavior consists, unlike OCD rituals, of a smaller behavioral repertoire. As seen in patients with OCD, quinpirole-treated animals performed these behaviors with a high rate of repetition. These findings suggest that quinpirole-induced behavior mimics only part of the compulsive behavior as shown in OCD patients.