The role of dopamine in alcohol self-administration in humans: individual differences.
OBJECTIVE
To clarify dopamine's role in alcohol self-administration in a heterogeneous sample of drinkers using acute phenylalanine/tyrosine depletion (APTD).


METHODS
Sixteen men with variable drinking histories were characterized on their ethanol-induced cardiac response, a marker previously proposed to index dopamine system reactivity and vulnerability to alcohol abuse. During separate sessions participants were administered (i) a nutritionally balanced (BAL) amino acid (AA) mixture, (ii) a mixture lacking the dopamine precursors, phenylalanine and tyrosine, and (iii) APTD followed by the dopamine precursor, L-DOPA. Five hours after AA administration, participants could earn units of alcohol using a progressive ratio breakpoint task.


RESULTS
Alcohol self-administration was reduced in the APTD and APTD+L-DOPA conditions relative to the BAL condition. In both cases the changes were predicted by ethanol-induced cardiac change.


CONCLUSIONS
The motivation to drink is likely regulated by more than one neurobiological mechanism. Individual differences in cardiac responsivity to ethanol might provide a peripheral marker of responsiveness to pharmacological manipulations of dopamine.
Barrett
Sean P
SP
Psychology Department, McGill University, 1033 Pine Avenue West, Montreal, Quebec, Canada.
Pihl
Robert O
RO
Benkelfat
Chawki
C
Brunelle
Caroline
C
Young
Simon N
SN
Leyton
Marco
M
D000328:Adult; D000428:Alcohol Drinking / Q000378:metabolism* / Q000523:psychology*; D000596:Amino Acids / Q000008:administration & dosage; D000704:Analysis of Variance; D004298:Dopamine / Q000378:metabolism*; D015259:Dopamine Agents / Q000008:administration & dosage; D004311:Double-Blind Method; D000431:Ethanol / Q000008:administration & dosage*; D006339:Heart Rate / Q000187:drug effects; D006801:Humans; D007206:Individuality; D007980:Levodopa / Q000008:administration & dosage; D008297:Male; D010649:Phenylalanine / Q000172:deficiency; D012646:Self Administration; D014443:Tyrosine / Q000172:deficiency
D000596:Amino Acids; D015259:Dopamine Agents; D000431:Ethanol; D014443:Tyrosine; D007980:Levodopa; D010649:Phenylalanine; D004298:Dopamine