Abstract
Adolescence is a critical period for the onset of tobacco smoking, with more than 90% of smokers beginning at this age. Clinical studies have shown that children who tried a single cigarette by the age of 11 continue to be susceptible to smoking throughout the rest of their lives. In animal models, it has been shown that adolescents exhibit unique responses to nicotine exposure, as compared to adults. Furthermore, subchronic treatment with a low dose of nicotine in early adolescence increases subsequent cocaine self‐administration. The purpose of this study was to examine the behavioral effects and age‐related neurochemical changes that occur after exposure to nicotine. Male Sprague‐Dawley rats aged P28 or P86, were given one or four daily i.v. injections of saline or nicotine (2 x 0.03 mg/kg/0.1 ml spaced 1 min apart). Immediately after the last injection, locomotor behavior was monitored for 30 minutes and brains were collected for anatomical analysis. Acute nicotine treatment produced increased locomotor activation in adolescents, which persists through the subchronic treatment. Adults show a decrease in activity after one injection of nicotine, whereas repeat nicotine treatment has no effect. Preliminary analysis of nicotine‐induced IEG expression has shown selective nicotine activation of limbic forebrain in adolescents. In vivo microdialysis studies are currently being conducted to further elucidate changes after nicotine exposure. These findings provide evidence that nicotine administration during adolescence causes unique neural adaptations not seen following treatment of adults.
Published Version
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