abstract
- The present study examines the influence of size of testing environment on the behavioral profile seen following injection of the dopamine D2 receptor agonist quinpirole (0.5 mg/kg, n = 16) or saline (n = 16). All rats were tested in a counterbalanced order in both a small and large environment. Oral (licking) behaviors were observed exclusively in the small environment and only in drug-treated rats; moreover, quinpirole increased rearing in the small but not large environment. Other behaviors--sniffing, face and body grooming--were affected by quinpirole but not in an environment-dependent manner. It is concluded that limiting environmental space promotes emergence of oral responding under quinpirole. The self-directed nature of this licking (paw- and tail-licking) may reflect a hierarchical transformation of quinpirole-induced hyperactivity from exploration of space to investigation of body parts.