INVESTIGADORES
PAUTASSI Ricardo Marcos
artículos
Título:
Opioid antagonists block the acquisition of ethanol-mediated conditioned preference in infant rats
Autor/es:
NIZHNIKOV M; PAUTASSI RM; TRUXELL E; SPEAR, N.E.
Revista:
ALCOHOL
Editorial:
Elsevier
Referencias:
Año: 2009 vol. 43 p. 347 - 358
ISSN:
0741-8329
Resumen:
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It has been difficult to find conditioned
preference for tactile cues paired with ethanol intoxication in rats. Toward
understanding the ontogeny of ethanol reinforcement, we aimed at establishing a
simple and reliable procedure for: (i) assessing primary appetitive conditioning
to ethanol in infant rats and (ii) discerning the role the opioid system plays in
ethanol-mediated conditioning at this age. Experiment 1 determined the
parameters (i.e., dose, interval of conditioning) for assessing
ethanol-mediated conditioning. Pups were then trained with differential
Pavlovian conditioning (Experiments 2 and 3) in which ethanol intoxication (1.0
2.0 g/kg, intragastrically or intraperitoneally delivered) was paired with a
tactile stimulus (sandpaper) while an alternative texture signaled the absence
of ethanols effects. Unpaired control conditions were also employed. Tactile
preferences were assessed after two conditioning sessions. Paired rats spent
significantly more time on sandpaper than unpaired controls, an effect that was
greater following intragastric administration of 1.0 than 2.0 g/kg ethanol.
This effect was replicated in Experiments 4a and 4c and found to be inhibited
by pretreatment with general (naloxone) or specific
(D-Pen-Cys-Tyr-D-Trp-Orn-Thr-Pen-Thr-NH2 [CTOP] and naltrindole) opioid
antagonists. Blood ethanol levels at conditioning were not altered by naloxone
(Exp. 4b). The study outlines a procedure that reveals appetitive conditioning
to ethanol by infant rats. The results are discussed in terms of a potential
ethanol-induced activation of the endogenous opioid system during the onset of
the intoxication process.