Comparison between behaviours elicited by high doses of amphetamine and fenfluramine: Implications for the concept of stereotypy

The behavioural effects of a range of high doses of D-amphetamine and DL-fenfluramine were investigated in rats. Subjects were observed individually for 1 min in every 5 for a period of an hour. During each observation period the presence of any of 6 behavioural patterns was recorded in an “all or none”; fashion Behaviour patterns recorded included: Rearing, Forward Locomotion, Immobility, Backward Locomotion, Circling and Head Swaying. The last 3 behaviours are considered “Abnormal”; in that they were never observed in saline treated controls. The results indicate that, at the doses used in this study, both compounds induce abnormal behaviours, the latency of onset of which is directly proportional to dose. For both compounds an inverse correlation was found between normal and abnormal behaviours. However, the type of abnormal behaviour observed differed considerably between drugs in that fenfluramine elicited Backward Walking and Circling with no Head Swaying, over the dose range 10–30 mg per kg; whilst the predominant abnormal behaviour elicited by D-amphetamine, over the range 5–20 mg per kg, was Head Swaying. At the highest doses of amphetamine used some Backward Walking was elicited, behaviour which was totally absent at the lower doses. The implications of these results for the concept of “stereotypy”; are discussed, and attention is drawn to an important distinction between abnormal and stereotyped behaviour.