Perseveration without hyperlocomotion in a spontaneous alternation task in rats sensitized to the dopamine agonist quinpirole

Behavioral sensitization induced by intermittent injections of the dopamine agonist quinpirole is characterized by hyperlocomotion and perseveration. This study tested whether in sensitized rats, the expression of perseverative behavior can be independent of hyperlocomotion. Rats received 10 injections of either quinpirole (0.5 mg/kg) or saline in a T-maze apparatus, a procedure that induced locomotor sensitization in the drugged animals. When tested later (under quinpirole) for spontaneous alternation in the same T-maze, in a discrete trial procedure, sensitized rats showed decreased spontaneous alternation, compared either to saline controls or acute quinpirole. The decrease in spontaneous alternation showed a tendency to be lower than chance level of alternation, suggesting perseveration. The possibility is discussed that the sensitization-reduced spontaneous alternation may relate to a diminution in the sense of task completion, and the increased perseveration may model a form of compulsive "checking" shown in obsessive-compulsive disorder.