The effects of psychomotor stimulants on stereotypy and locomotor activity in socially-deprived and control rats.

Using measures of locomotor activity and stereotypy, dose-response curves to several psychomotor stimulant drugs were obtained on rats reared in deprived or normal environments. At both 0.5 and 1.5 mg/kg d-amphetamine, the deprived rats exhibited more intense stereotyped behavior than the control rats. At 5.0 mg/kg, both groups showed maximum response. However, there was no significant difference between the two groups in locomotor response. A similar pattern of results was found for pipradrol, cocaine, and apomorphine. The findings show that different social and environmental experience can modify the response to dopaminergic stimulating agents. The results also suggest that stereotyped behavior should not be considered on the same continuum as locomotor activity. These two behaviors may be mediated by different mechanisms.