Social interaction modulates the intensity of compulsive checking in a rat model of obsessive-compulsive disorder (OCD).

Here we present an empirical study that provides a basis for understanding the impact of the social environment on individuals with mental disorders. Rats treated chronically with the dopamine-agonist quinpirole offer a solid animal model for compulsive behavior that has been comprehensively evaluated and validated in numerous studies. Moreover, the method of behavioral analysis used in the quinpirole rat model has been similarly applied to the analysis of compulsive rituals in OCD patients, revealing similarities to the structure of compulsions in the quinpirole-sensitized rats. Here, we examined how compulsive checking by quinpirole-sensitized rats was modulated by the presence of a partner that was also treated with quinpirole or a partner that was treated with saline, compared to the typical expression of compulsive checking shown by rats tested alone. Our results demonstrate that the presence of a partner does indeed modulate the performance of checking behavior. Specifically, the vigor of compulsive checking was attenuated in the presence of a saline-treated partner, and augmented in the presence of a quinpirole-treated partner. This finding provides compelling evidence that social interactions modulate the expression of compulsive checking in the quinpirole rat model of OCD. This uncovering of the effectiveness of social modulation, indicates the quinpirole preparation as a paradigm for investigating the mechanisms by which the social environment modulates the development and expression of OCD. More generally, it presents a paradigm for the study of the influence of drug effects as a function of social interaction.