The ontogeny of ethanol aversion

Abstract

Recent work has suggested separate developmental periods within the broader framework of adolescence, with data suggesting distinct alterations and vulnerabilities within these intervals. While previous research has suggested reduced sensitivity to the aversive effects of alcohol in adolescence relative to adults, a more detailed ontogeny of this effect has yet to be conducted. The adolescent brain undergoes significant transitions throughout adolescence, including in regions linked with drug reward and aversion. The current study aimed to determine the ontogeny of ethanol aversion by utilizing a conditioned taste aversion procedure at six different ages to test the hypothesis that the transitions into, through, and out of adolescence are associated with ontogenetic alterations in sensitivity to the aversive properties of ethanol. Non-deprived animals given Boost® as the conditioned stimulus (CS) were used in Experiment 1, whereas Experiment 2 used water-restricted animals provided with a saccharin/sucrose solution as the CS. In both experiments, an attenuated sensitivity to the aversive properties of ethanol was evident in adolescents compared to adults, although more age differences were apparent in water deprived animals than when a highly palatable CS was given to ad libitum animals. Overall, the data suggest an attenuated sensitivity to the aversive properties of ethanol that is most pronounced during pre- and early adolescence, declining thereafter to reach the enhanced aversive sensitivity of adults.

Keywords: Adolescence; Conditioned taste aversion; Ethanol; Water deprivation.

Figure 1

In males given Boost® as the CS, the 3 youngest age groups required a higher ethanol dose (2 g/kg) to express CTA when compared to the 3 older ages (1.5 g/kg). *denotes significant difference from age-matched saline control

Figure 2

In males given SS as the CS, notable age differences across age were evident in ethanol CTA, with early adolescents failing to develop a CTA, preadolescents displaying significant CTA at only the 2 g/kg dose, and CTA expressed among older adolescents beginning at 1.5 g/kg, and among adults at all doses. * denotes significant difference from age-matched saline control

Figure 3

In females given SS as the CS, early and preadolescents displayed significant CTA at only the 2 g/kg dose, older adolescents beginning at a dose of 1.5 g/kg, and adults at all doses. * denotes significant difference from age-matched saline control