Environmental experience produces qualitative changes in the stimulant effects of beta-phenylethylamine in rats

The effects of beta-phenylethylamine (PEA 6.25, 12.5, and 25.0 mg/kg IP) on spontaneous motor activity were examined in rats before (novel situation) and after (familiar situation) they had experience of the test environment, in an undrugged state. In a novel cage, 12.5 mg/kg PEA stimulated rearing and locomotion. A dose of 25.0 mg/kg PEA also increased rearing and produced stereotyped head movements, but did not increase locomotion, in a novel environment. In a familiar cage, both 12.5 and 25.0 mg/kg PEA stimulated locomotion and sniffing, whereas rearing was unaffected by PEA treatment under these conditions. These data provide a striking instance of a qualitative change in the behavioural response to a psychostimulant compound which is associated with the relative familiarity of the animal with the test environment. In addition, the results show that PEA induces stereotypy at high doses and increases locomotor activity at moderate doses, which is a further illustration of the similarity in the unconditioned behavioural effects of PEA and amphetamine.