Comparing the Acquisition of Self-Administration of Cigarette Smoke Extract vs. Nicotine in
Adolescent and Adult Male Rats
Hana R. Smith
Mentor: Frances Leslie
To challenge the current animal model of using nicotine alone to study tobacco dependence, we have
established a model of intravenous self-administration of cigarette smoke extract (CSE). Previous research in
our lab has shown that adult male rats will not only self-administer CSE but that they find it more reinforcing
than nicotine at the 7.5µg/kg/inf dose. We now test the hypothesis that CSE will be even more reinforcing in
adolescence, the age at which most humans start to use tobacco. Adolescent male rats (aged postnatal day 32)
and adults were trained to work for food pellets on an FR1TO20 schedule (one food pellet per lever press
with a timeout period of 20 seconds). After rats reached the reinforced lever press threshold (R=35 and 50
for adolescents and adults, respectively), they underwent surgery in which a catheter was implanted into the
right jugular vein. After three days recovery, rats underwent three progressively harder schedules of lever
pressing: FR1TO20, FR2TO20, and FR5TO20 for one of 5 doses of CSE or nicotine (Nic) (0, 3.75, 7.5, 15,
or 30µg/kg per infusion). We have found that both adolescent and adult rats will self-administer CSE and Nic
at all doses. Preliminary results also suggest that there are no differences in CSE and Nic reinforcement at
either age, but that adolescents show a dose-related increase in non-reinforced responding which leads to an
overall increase in drug intake.