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The Enigma of Conditioned Taste Aversion
Learning:
Stimulus Properties of 2-phenylethylamine Derivatives
A. J. GREENSHAW1, S. TURKISH2,
B. A. DAVIS2
1Neurochemical Research Unit, Department of
Psychiatry, University of Alberta and 2Neuropsychiatric
Research Unit, University of Saskatchewan, Canada
Summary
The functional aversive stimulus properties of several IP doses
of (±)-amphetamine
(1.25-10 mg.kg-1),
2-phenylethylamine (PEA, 2.5-10 mg.kg-1, following inhibition of
monoamine oxidase with pargyline 50 mg.kg-1) and
phenylethanolamine (6.25-50 mg.kg 1) were measured with the
conditioned taste aversion (CTA) paradigm.
A two bottle choice procedure was used, water vs. 0.1 %
saccharin with one conditioning trial and three retention
trials. (±)-Amphetamine
and phenylethanolamine induced a significant conditioned taste
aversion but PEA did not.
(±)-Amphetamine
and PEA increased spontaneous locomotor activity but
phenylethanolamine had no effects on this measure. Measurement
of whole brain levels of these drugs revealed that the peak
brain elevation of PEA occurred at approximately 10 min whereas
the peak elevations of ()-amphetamine and phenylethanolamine
occurred at approximately 20 min. The present failure of PEA to
elicit conditioned taste aversion learning is consistent with
previous reports for this compound. The differential functional
aversive stimulus effects of these three compounds are
surprising since they exhibit similar discriminative stimulus
properties and both (±)-amphetamine
and PEA are self-administered by laboratory animals. The present
data suggest that time to maximal brain concentrations following
peripheral injection may be a determinant of the aversive
stimulus properties of PEA derivatives.
Key
words
2-phenylethylamine • ()-amphetamine • Phenylethanolamine •
Conditioned taste aversion • Locomotor activity • Drug levels
Reprint
requests
Dr. A.J. Greenshaw, Department of Psychiatry, 1E7.44 WMC
University of Alberta, Edmonton, AB T6G 2R7, Canada, e-mail:
andy.greenshaw@ualberta.ca
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