Enhancement of sensory preconditioning by a moderate dose of ethanol in infant and juvenile rats

Abstract

Little is known regarding the effects of acute ethanol on learning and memory among infant and juvenile rats. Two experiments were designed to evaluate the influence of various doses of ethanol administration on sensory preconditioning and primary conditioning in preweanling (16-day-old) and postweanling (28-day-old) rats. Moderate doses of ethanol facilitated conditioning at both ages. In the absence of ethanol, sensory preconditioning was not statistically significant among postweanlings in Experiment 1, although the phenomenon was clear and robust among preweanlings. Sensory preconditioning was facilitated by administration of doses of 0.8 and 1.2 g/kg ethanol in preweanlings and a dose of 1.6 g/kg ethanol in postweanlings, whereas sensory preconditioning was impaired in preweanlings by a high dose (2.4 g/kg) of ethanol. This reflected a shift to the right, between the preweaning and the postweaning periods, in the dose-response curve. It was determined in Experiment 2 that the effect of ethanol on sensory preconditioning could not be explained by stimulus generalization or an effect of ethanol on first-order conditioning, confirming the effect of ethanol on learning of the odor-odor association in the preexposure phase. The basis for a dose-dependent biphasic effect of ethanol on sensory preconditioning is discussed.