Megan J Shram1, Zhaoxia Li, Anh D Lê. 1. Department of Neuroscience, Centre for Addiction and Mental Health, 33 Russell Street, T700, Toronto, ON, M5S 2S1, Canada. megan_shram@camh.net
Abstract
RATIONALE: Epidemiological evidence suggests that adolescents may exhibit a unique susceptibility to the motivational effects of nicotine compared to adults. In contrast to the hypothesis of an enhanced vulnerability to nicotine during adolescence, we have observed that nicotine is less reinforcing in adolescent compared to adult rats using a progressive ratio reinforcement schedule in an operant self-administration procedure, although prior operant conditioning experience may have masked differences in initial sensitivity to nicotine. OBJECTIVES: This study examined the spontaneous acquisition of nicotine self-administration in adolescent (postnatal day (PD) 31) and adult (PD87) male Wistar and Long-Evans rats. MATERIALS AND METHODS: Rats self-administered nicotine (0.015 or 0.03 mg/kg/infusion, i.v.) during 2-h operant conditioning sessions under fixed-ratio-1 (FR1) and FR3 reinforcement schedules for six sessions each. A subset of rats (adolescents: PD42, adults: PD98) underwent extinction of responding and nicotine priming-induced reinstatement (0.15 mg/kg, s.c.). In a separate group of rats, saccharin self-administration (0.1 ml of 0.2% w/v) was tested to determine the specificity of our findings with nicotine. RESULTS: A greater proportion of adult compared to adolescent rats acquired self-administration of 0.015 mg/kg/infusion nicotine, but both age groups readily acquired self-administration of 0.03 mg/kg/infusion nicotine and saccharin. Age differences in extinction of responding for nicotine or saccharin depended upon strain, but priming-induced reinstatement was similar across age and strain. CONCLUSIONS: The current findings are consistent with those obtained under a more demanding progressive ratio reinforcement schedule and suggest that adolescents, compared to adults, may not be as sensitive to the reinforcing effects of nicotine.
RATIONALE: Epidemiological evidence suggests that adolescents may exhibit a unique susceptibility to the motivational effects of nicotine compared to adults. In contrast to the hypothesis of an enhanced vulnerability to nicotine during adolescence, we have observed that nicotine is less reinforcing in adolescent compared to adult rats using a progressive ratio reinforcement schedule in an operant self-administration procedure, although prior operant conditioning experience may have masked differences in initial sensitivity to nicotine. OBJECTIVES: This study examined the spontaneous acquisition of nicotine self-administration in adolescent (postnatal day (PD) 31) and adult (PD87) male Wistar and Long-Evans rats. MATERIALS AND METHODS:Rats self-administered nicotine (0.015 or 0.03 mg/kg/infusion, i.v.) during 2-h operant conditioning sessions under fixed-ratio-1 (FR1) and FR3 reinforcement schedules for six sessions each. A subset of rats (adolescents: PD42, adults: PD98) underwent extinction of responding and nicotine priming-induced reinstatement (0.15 mg/kg, s.c.). In a separate group of rats, saccharin self-administration (0.1 ml of 0.2% w/v) was tested to determine the specificity of our findings with nicotine. RESULTS: A greater proportion of adult compared to adolescent rats acquired self-administration of 0.015 mg/kg/infusion nicotine, but both age groups readily acquired self-administration of 0.03 mg/kg/infusion nicotine and saccharin. Age differences in extinction of responding for nicotine or saccharin depended upon strain, but priming-induced reinstatement was similar across age and strain. CONCLUSIONS: The current findings are consistent with those obtained under a more demanding progressive ratio reinforcement schedule and suggest that adolescents, compared to adults, may not be as sensitive to the reinforcing effects of nicotine.
Authors: Laura E O'Dell; Scott A Chen; Ron T Smith; Sheila E Specio; Robert L Balster; Neil E Paterson; Athina Markou; Eric P Zorrilla; George F Koob Journal: J Pharmacol Exp Ther Date: 2006-10-18 Impact factor: 4.030
Authors: Arpana Agrawal; Julia D Grant; Mary Waldron; Alexis E Duncan; Jeffrey F Scherrer; Michael T Lynskey; Pamela A F Madden; Kathleen K Bucholz; Andrew C Heath Journal: Prev Med Date: 2006-05-11 Impact factor: 4.018
Authors: Dorothy K Hatsukami; Kenneth A Perkins; Mark G Lesage; David L Ashley; Jack E Henningfield; Neal L Benowitz; Cathy L Backinger; Mitch Zeller Journal: Tob Control Date: 2010-10 Impact factor: 7.552
Authors: Laura E Rupprecht; Tracy T Smith; Rachel L Schassburger; Deanne M Buffalari; Alan F Sved; Eric C Donny Journal: Curr Top Behav Neurosci Date: 2015
Authors: Edward D Levin; Susan Slade; Corinne Wells; Marty Cauley; Ann Petro; Analise Vendittelli; Michael Johnson; Paul Williams; Kofi Horton; Amir H Rezvani Journal: Behav Brain Res Date: 2011-08-11 Impact factor: 3.332