Date Thesis Awarded

5-2021

Access Type

Honors Thesis -- Access Restricted On-Campus Only

Degree Name

Bachelors of Science (BS)

Department

Psychology

Advisor

Robert Barnet

Committee Members

Pamela Hunt

Paul Vierthaler

Abstract

The effects of exposure to nicotine during adolescence on later adulthood are not well understood. This is an important issue given the prevalence of adolescent smoking and nicotine vaping use. Some research using animal models has suggested adolescent nicotine can produce long-lasting increases anxiety that persist into in adulthood. The most common behavioral paradigms in experimental research on fear and anxiety, such as the open field test and elevated plus maze, measure nonsocial forms of anxiety. As a result, there is a lack of information about nicotine’s long-term impact on social, as opposed to nonsocial, anxiety. The current study uses the three-chamber sociability test in rats, a task that measures anxiety as a reduction in normal prosocial behavior, in order to examine the long-term effects of adolescent nicotine on social anxiety in adulthood. Male and female Sprague-Dawley rats received twice-daily intraperitoneal injections from postnatal day 28-42 (PD28-42), an adolescent period of the rat. Rats received injections of either 0.15 mg/kg nicotine, 0.40 mg/kg nicotine, or saline solution. In early adulthood at approximately PD60, animals were tested for anxiety in the three-chamber sociability paradigm during a 10-min test session. Time and sex dependent effects were observed. Male rats exposed to 0.40 mg/kg nicotine during adolescence were found to exhibit a biphasic sociability preference during the test in which they had elevated sociability in the first five-minutes of the test session and inhibited sociability in the second five-minutes of the test session. Female rats’ sociability behavior was independent of drug condition. The biphasic effect in males may be the result of an interaction between two separate effects of adolescent nicotine exposure, an immediate cognitive deficit that increased social behavior by impairing habituation to novel social partners during the early part of the test session, followed by a delayed anxiogenic effect produced by the long-lasting impact of adolescent nicotine on the fear system.

Keywords: nicotine, adolescence, social anxiety, learning and memory, sex differences

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