Long-term changes in fear conditioning and anxiety-like behavior following nicotine exposure in adult versus adolescent rats.
Adolescent nicotine exposure is associated with long-term use, and it has been suggested that this vulnerability to addiction may relate to lasting anxiogenic effects of the drug. However, few studies have addressed long-term effects of adolescent nicotine, and fewer yet have compared adolescent to adult exposure. Male and female Long-Evans rats continuously received nicotine bitartrate or sodium tartrate via osmotic mini-pumps over 15 days either during adolescence (p28-42) or adulthood (p85-99). Initial nicotine dose (free base) was either low (1 mg/kg/day) or high (2 mg/kg/day). Open field behavior and fear conditioning were assessed in adulthood, 1 month post-dosing. Animals pretreated with nicotine during adolescence showed less center time in a novel open field than sham controls. Conversely, the two nicotine doses differentially affected fear conditioning. Animals pretreated with low nicotine during adolescence demonstrated superior acquisition of the task compared to sham control animals; however, unlike either high nicotine-pretreated or sham control animals, they failed to extinguish the learned behavior. In contrast, animals pretreated during adulthood did not behave significantly different from sham controls on either task. Overall, nicotine-pretreatment during adolescence induced effects on behaviors related to fear and anxiety in adulthood, while comparable pretreatment during adulthood failed to produce significant residual effects.
Smith
Laura N
LN
Department of Psychology, George Mason University, MS 3F5, Fairfax, VA 22030, USA. lsmithv@gmu.edu
McDonald
Craig G
CG
Bergstrom
Hadley C
HC
Brielmaier
Jennifer M
JM
Eppolito
Amy K
AK
Wheeler
Tracey L
TL
Falco
Adriana M
AM
Smith
Robert F
RF
D000367:Age Factors; D000818:Animals; D001007:Anxiety / Q000139:chemically induced*; D001522:Behavior, Animal / Q000187:drug effects*; D003216:Conditioning, Operant; D005239:Fear; D005260:Female; D008297:Male; D009538:Nicotine / Q000494:pharmacology*; D051381:Rats; D020318:Rats, Long-Evans
D009538:Nicotine