Examination of the rewarding effects of nicotine during the adolescent period of development
Clinical studies suggest that there is a heightened vulnerability to nicotine dependence during adolescence and that exposure to nicotine during this period may facilitate drug dependence later in adulthood. This study compared the rewarding effects of nicotine in adolescent, adult, and adult rats pre-exposed to nicotine during adolescence using conditioned place preference (CPP) procedures. Male Wistar adolescent (postnatal day [PND] 28-42) and adult (PND 60-72) rats were tested for their initial preference for either of two distinct compartments of our conditioning apparatus. Six days later, conditioning was conducted over eight days where rats received nicotine (0, 0.2, 0.4, 0.6, 0.8 or 1.2 mg/kg; sc, base; n=8-14 per group) in their initially non-preferred side on one day and saline in the other compartment on alternate days. Following conditioning, rats were tested for CPP. A subsequent study compared CPP produced by various doses of d-amphetamine (0, 0.5, 1.0 or 2.0 mg/kg, base; n=8-14 per group) in adolescent and adult rats. This was done in order to compare developmental differences to another psychostimulant drug with rewarding properties. In a final study, we prepared adolescent rats with subcutaneous pumps that delivered nicotine (4.7 mg/kg/per day; base) for 14 days. These rats were conditioned later as adults (n=9-14 per group) using the same nicotine doses and conditioning procedures as described previously. Nicotine produced CPP in an inverted U-shaped dose-response manner in both age groups. However, adolescents displayed a larger upward shift in CPP that was significant across a larger range of doses relative to adults. These results appear to be nicotine-specific, since there were no developmental differences to CPP produced by d-amphetamine. Pre-exposure to nicotine during adolescence decreased the aversive effects of the highest nicotine dose in adult rats. Our findings support the hypothesis that adolescence is a period of enhanced vulnerability to nicotine. ^
Psychology, Psychobiology|Psychology, Behavioral|Psychology, Experimental
Torres, Oscar Valentin, "Examination of the rewarding effects of nicotine during the adolescent period of development" (2007). ETD Collection for University of Texas, El Paso. AAI1449738.