LOCOMOTOR AND REWARDING EFFECTS OF AMPHETAMINE IN ENRICHED, SOCIAL, AND ISOLATE REARED RATS

This study examined the influence of environmental enrichment on the b ehavioral response to amphetamine. Beginning at 21 days of age, rats w ere raised in one of three different environmental conditions: a) an e nriched condition CEC), in which animals were caged in groups and prov ided with novel objects daily; b) a social condition (SC), in which an imals were caged in groups without any novel objects; and c) an isolat ed condition (IC), in which animals were caged individually without an y novel objects. At 53 days of age, animals from each environmental co ndition were assessed for amphetamine-induced changes in locomotor act ivity and reward using the conditioned place preference (CPP) paradigm . Results from saline-injected control animals indicated that EC anima ls exhibited less vertical activity than IC animals when exposed to th e CPP apparatus. When challenged with amphetamine (0.5 or 2.0 mg/kg), there were no significant differences between SC and IC animals in eit her locomotor behavior or CPP. However, EC animals exhibited more hori zontal and vertical activity following amphetamine than both the SC an d IC animals. Similarly, EC animals exhibited a greater magnitude of a mphetamine-induced CPP than both the SC and IC animals.