RAT PUPS REJECT ETHANOL’s SENSORY CUES AND ARE POSITIVELY REINFORCED BY THE DRUG’s POSTABSORTIVE EFFECTS

PAUTASSI, R.M.; MOLINA, J.C.; SPEAR, N.E.

Chicago, Illinois, EEUU

Congreso; 2007 Annual Meeting of the Research Society on Alcoholism.; 2007

Research Society on Alcoholism

Operant self-administration studies suggest both aversive and appetitive hedonic effects of EtOH in preweanling rats (Pautassi et al., 2006). Specifi cally, pups are reluctant to perform an operant response when reinforced with intraoral EtOH infusion, a result suggesting aversive orosensory properties of the drug. Yet, after ethanol intake takes place, its postabsortive effects seem capable of supporting appetitive learning. Two experiments were conducted to further test these effects. Both studies included a pre-exposure phase on postnatal day 13 (PD13) in which pups were intraorally stimulated with water or 5% v/v EtOH (30 2-s pulses, 5 ul per pulse). In Experiment 1, pups were given one daily conditioning trial on PD14 and PD15. They were exposed to a tactile conditioned stimulus (CS, sandpaper or smooth cardboard) for 20 min while experiencing either intraorally delivered EtOH (5% v/v) or water (65 2-s pulses, 5 ul each). Tactile preferences were assessed on PD16. ANOVAs revealed that pups spent significantly less on the CS paired with acute EtOH infusion relative to time spent on the alternative CS, F (1,46) = 5.86; p < 0.005. No significant main effect or interactions involving pre-exposure condition were detected. In Experiment 2 pups were exposed to sandpaper while intraorally infused with 5% v/v EtOH or during a later EtOH postinfusion interval (14.5–27 min). A two-way tactile locational test (sandpaper vs. novel texture) was conducted on PD 16. EtOH-preexposed animals that experienced sandpaper paired with postabsortive EtOH exhibited a significant preference for this texture, F(1, 89) = 8.35; p < 0.005. This preference was observed even relative to a control group that experienced non-reinforced exposure to the tactile CS during conditioning, F (1, 89) = 4.00, p < 0.05. These results confirm the hypotheses that although intraoral ethanol acts as an aversive unconditioned stimulus, a brief preexposure to the orosensory features of EtOH allows later expression of appetitive learning mediated by the postabsortive effects of the drug.