Preexposure during or following adolescence differently affects nicotine-rewarding properties in adult rats.
Psychopharmacology. 2005-09-15; 184(3-4): 382-390
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1. Psychopharmacology (Berl). 2006 Mar;184(3-4):382-90. Epub 2005 Sep 15.
Preexposure during or following adolescence differently affects
nicotine-rewarding properties in adult rats.
Adriani W(1), Deroche-Gamonet V, Le Moal M, Laviola G, Piazza PV.
(1)INSERM U. 588, Institut François Magendie, Domaine de Carreire, Rue C.
Saint-Saëns, Bordeaux Cedex, 33077, France.
RATIONALE: Many people come in contact with psychoactive drugs, yet not all of
them become addicts. Epidemiology shows that a late approach with cigarette
smoking is associated with a lower probability to develop nicotine dependence.
Exposure to nicotine during periadolescence, but not similar exposure in the
postadolescent period, increases nicotine self-administration in rats, but
underlying mechanisms remain poorly understood.
OBJECTIVE: We investigated whether exposure to nicotine during or after
adolescence would alter rewarding properties of the same drug at adulthood, as
assessed by place conditioning.
MATERIALS AND METHODS: Periadolescent (PND 34-43) or postadolescent (PND 60-69)
rats were injected with saline or nicotine (0.4 mg kg(-1)) for 10 days. The rats
received three pairings with saline and three pairings with nicotine (0, 0.3, or
0.6 mg kg(-1)) 5 weeks after pretreatment. The rats were then tested for place
conditioning in a drug-free state.
RESULTS: Upon first exposure to the apparatus, animals pretreated with nicotine
during adolescence showed elevated novelty-induced activation. The 0.3 (but not
the 0.6) mg kg(-1) dose failed to produce both ongoing locomotor sensitization
and place conditioning in animals pretreated with nicotine following adolescence.
This suggests a rightward shift in the dose-response curve, namely, a reduced
efficacy of nicotine. Conversely, the same dose was effective in
saline-pretreated controls and noteworthy in rats pretreated during adolescence.
CONCLUSION: Exposure following the adolescent period might diminish the risk to
develop nicotine dependence. As for human implications, findings are consistent
with a reduced vulnerability to nicotine addiction in people who start smoking
late in their life.
PMID: 16163527 [Indexed for MEDLINE]