Concurrent measures of feeding and locomotion in rats

Psychostimulants including amphetamine and cocaine induce locomotion and stereotypy and suppress eating. Studies of the biobehavioral actions of psychostimulants commonly focus on locomotion and less commonly on feeding, and only rarely are these measures considered in conjunction within the same animal. Inasmuch as hyperactivity induced by a psychostimulant may compete with other motor behaviors, including eating, it would be important to concurrently assess changes in eating and locomotion after psychostimulant treatment. The present paper describes a modification of an automated activity chamber in which minute-by-minute recordings of food consumption are gathered in parallel with an assessment of locomotion. The present experiment illustrates the method by characterizing the temporal changes in locomotion and eating produced by administration of hypophagic doses of nicotine tartrate (0.28 mg/kg (as the base), IP) or cocaine hydrochloride (7.5 mg/kg, IP). At these doses, nicotine suppressed eating and locomotion, whereas cocaine suppressed eating, but facilitated forward locomotion. These outcomes support the viability of this apparatus and the concurrent method for the dissociation of feeding and locomotion.