Infant rats exhibit aversive learning mediated by ethanol's orosensory effects but are positively reinforced by ethanol's post-ingestive effects.
Previous work suggest aversive and appetitive hedonic effects of intraorally delivered EtOH in pre-weanling rats. Pups are reluctant to perform an operant response when reinforced with intraoral EtOH infusions, a result suggesting aversive orosensory properties of EtOH. Yet, post-absorptive effects of ethanol seem capable of supporting appetitive conditioning. Two experiments were conducted to test this phenomenon. Both included a pre-exposure phase (postnatal day 13, PD13) comprising intraoral stimulation with water or EtOH. In Experiment 1, pups were given pairings between a tactile conditioned stimulus (CS) and intraoral infusions of EtOH or water. A subsequent tactile preference test revealed that pups spent significantly less on the EtOH-related CS relative to time spent on the alternative CS. In Experiment 2 pups were exposed to a texture CS (sandpaper) while intraorally infused with EtOH or during a later EtOH post-infusion interval. A tactile locational test conducted on PD16 indicated that EtOH-pre-exposed animals that experienced sandpaper paired with EtOH's post-absorptive effects exhibited a significant preference for the CS, even relative to a control group that experienced non-reinforced exposure to the tactile CS during conditioning. These results confirm that intraoral ethanol acts as an aversive tastant. A brief pre-exposure to EtOH allows later expression of appetitive learning mediated by the drug's post-ingestive effects.
Pautassi
Ricardo Marcos
RM
Center for Developmental Psychobiology, Binghamton University, Binghamton, NY 13902-6000, USA. pautassi@binghamton.edu
Molina
Juan Carlos
JC
Spear
Norman
N
D000280:Administration, Inhalation; D000284:Administration, Oral; D000704:Analysis of Variance; D000818:Animals; D000831:Animals, Newborn / Q000523:psychology*; D001362:Avoidance Learning / Q000187:drug effects*; D002492:Central Nervous System Depressants / Q000008:administration & dosage / Q000494:pharmacology*; D003463:Cues; D003627:Data Interpretation, Statistical; D000431:Ethanol / Q000008:administration & dosage / Q000494:pharmacology*; D051381:Rats; D017207:Rats, Sprague-Dawley; D012054:Reinforcement, Psychology; D012903:Smell / Q000187:drug effects*; D013649:Taste / Q000187:drug effects*; D014110:Touch / Q000187:drug effects
D002492:Central Nervous System Depressants; D000431:Ethanol