Patterns of locomotor and stereotypic behavior during continuous amphetamine administration in rats

The present study examined the behavioral effects of continuous subcutaneous infusion of amphetamine (AMPH) to rats. Saline and 3 AMPH doses were infused for 96 hr (0.2 mg/kg/hr, 0.55 mg/kg/hr, 0.9 mg/kg/hr; n = 12). Locomotor behavior, grooming, gnawing and licking, sniffing, and head-bobbing were recorded for each animal for 1 hr in the light cycle and 1 hr in the dark cycle. The low dose AMPH animals exhibited increased locomotor activity. The medium and high dose groups developed similar behavioral patterns consisting of increased grooming and sniffing and changes in circadian rhythms of activity. Although most behaviors exhibited were similar to those discussed in previous literature describing the effects of chronic amphetamine, the pattern of the behaviors was not. Furthermore, continuous administration of AMPH seems to reliably increase the frequency of behaviors which are rarely observed after acute or chronic amphetamine. This finding has important implications since administration of AMPH to rats has been suggested to be an animal model of schizophrenia.