Year: 2014
Type: article
Abstract: Tobacco product use is the leading preventable cause of death in the United States. Nearly 90% of current daily smokers initiated use during adolescence. Moreover, although national rates of tobacco use by adults have declined in recent years, adolescent initiation remains high. Despite this, little is known about adolescent initiation and use. The present study sought to determine the effects of sex and developmental stage in the acquisition of nicotine self-administration, across a range of doses paired with different nonpharmacological cues. Adolescent (postnatal day [P] 30) and adult (P90) male and female rats with unlimited access to food were allowed to nosepoke on a fixed ratio 2 schedule to intravenously self-administer nicotine (3, 10, 30, or 100 μg/kg/infusion) paired with a moderately reinforcing visual reinforcer (VS) or an initially neutral stimulus light presentation (conditioned stimulus; CS), during daily 1-h sessions. The lowest doses of nicotine (3 or 10 μg/kg) paired with CS presentations did not support acquisition of self-administration in adolescents; however, when paired with VS both low doses engendered acquisition. While adolescents did not acquire at 10 μg/kg + CS, both male and female adults acquired self-administration in this condition. All four sex and age groups acquired self-administration, and earned a similar number of infusions when responding for 30 μg/kg nicotine paired with CS presentations. When paired with VS, adolescents, particularly males, responded more for 30 μg/kg nicotine than adults. Cue condition did not affect adult acquisition for either 10 or 30 μg/kg. Finally, 100 μg/kg supported the acquisition of self-administration for male and female adolescents when paired with either CS or VS, at rates comparable to 30 μg/kg. These results demonstrate that adolescent rats will respond for low doses of nicotine when combined with a moderate reinforcer (VS), but do not respond more than adults for a moderate dose of nicotine. Our finding that a low nicotine dose may enhance responding for VS during adolescence suggests that combination of nicotine exposure with mild rewards may lead to increased exposure to nicotine, and result in nicotine self-administration.
Author: Rachel L. Schassburger
Language: English
Field: Medicine
Domain: Health Sciences
Open Access status: green
OpenAlex ID: W167968846