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ETHANOL ACUTE INTOXICATION DISRUPTS THE ACQUISITION OF AN ODOR AVERSION IN INFANT RATS Pautassi R.M., Melloni C., Ponce L.F., Spear N. E. & Molina J.C. Instituto Ferreyra, Argentina, Dept. of Psychology, Binghamton University, NY and Fac. de Psic., UNC. Preweanling pups show a remarkable capacity to generate associative memories through the pairing between a neutral cue and a biologically relevant event. Yet, recently we have been unable to replicate previous research (Molina & Chotro, 1989) that found appetitive conditioning in young rats when pairing a neutral odor cue with the intraoral infusion of sweetened solutions. Specifically, we have observed that pups avoid an odor previously paired with sucrose infusion, a result seemingly caused by aversive properties inherent to the intraoral infusion procedure. Interestingly, Molina & Chotros work took advantage of the fact that about 10% of ethanol (EtOH) is excreted unchanged through respiration and salivation, thus allowing odor perception of EtOH during the toxic state. Consequently, their conditioning procedure was defined by the contiguity between alcohol intoxication and the availability of sucrose, and resulted in an enhanced preference for EtOHs odor. Here, we examined whether EtOHs intoxication is critical in terms of modulating the expression of an associative learning comprising the pairing of a novel odor and sucrose. Fourteen-day old Wistar rats were administered with ethanol (0.25, 0.5 or 1.25 g/kg) or vehicle and were then exposed during 5 to a lemon-scented chamber while intraorally infused with sucrose (12% v/v). Four of these pairings were conducted immediately after EtOH administration. Control pups experienced these stimuli explicitly unpaired. Blood ethanol concentrations attained 10 after administration with the described doses were equivalent to 11, 39 and 83 mg%, respectively. On postnatal day 15 animals were tested in an odor preference test. ANOVAs indicated that animals administered with vehicle exhibited a strong aversion to the lemon odor relative to control subjects. This aversion was reduced in those pups that received the 0.5 and 1.25 g/kg doses while completely vanished in those treated with 0.25 g/kg. This result indicates that EtOHs unconditional effects modulate the acquisition of aversive associative memories, a phenomenon that probably explains Molina & Chotros (1989) results. Recent research shows that infants are highly sensitive to EtOHs anxiolytic properties, a phenomenon that probably mediates the effects of the drug upon the attenuation of aversively motivated memories.

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