Repeated administration of amphetamine (AMPH) produces behavioral sensitization,
a proposed model for the escalation of drug use characteristic of human addicts. β-
Phenylethylamine (PEA) is an endogenous trace amine found in mammalian brain and
resembles AMPH both structurally and behaviorally. Previously, it has been reported
that chronic PEA administration produces behavioral sensitization to the challenges of
AMPH. However, these data were obtained with very high amount of PEA for a
relatively long period of time. Further, the effect of PEA challenge on the expression
of behavioral sensitization developed by AMPH pre-exposures has not been tested yet.
Thus, we examined in the present experiment the expression of behavioral sensitization
with AMPH challenge after a mild chronic PEA treatment. Rats were repeatedly
administered with systemic injections of saline, β-phenylethylamine (PEA) (10 or 50
mg/kg), or amphetamine (AMPH) (1.5 mg/kg). When challenged a week after the last
pre-injection, rats pre-exposed to either PEA or AMPH showed behavioral sensitization
to AMPH (1.0 mg/kg), while these effects were not observed to PEA (50 mg/kg) itself.
These results demonstrate that repeated exposure to PEA produces behavioral sensitization
to AMPH challenge, while PEA challenge has no effect on the expression of
behavioral sensitization developed by AMPH pre-exposures, suggesting that PEA may
play a role in the development of locomotor sensitization to AMPH, but not in the expression
of it.
Key words: β-phenyl