Ketamine-induced locomotion in rats in an open-field

The effects of ketamine on locomotion in an open-field were determined in hooded rats. Animals were given intraperitoneal injections of saline, or of 1, 10, 50 or 100 mg ketamine/kg body weight on separate days. Open-field behavior was examined for 60 min following injection. The 50 mg/kg dose of ketamine produced an increase in locomotion which peaked approximately 30 min after injection. A cataleptic immobility produced by the 100 mg/kg dose was followed by postanesthetic locomotion. The ketamine-induced locomotion consisted largely of ambulation about the perimeter of the field and was accompanied by ataxia, but included relatively little tight circling (rotation) during the peak of activity. Comparisons with the results of past research suggests that test-chamber design influences the type of locomotion induced by ketamine.