Adolescent male Wistar rats are more responsive than adult rats to the conditioned rewarding effects of intravenously administered nicotine in the place conditioning procedure.
The initiation of smoking typically begins during adolescence, suggesting that nicotine may have different motivational effects during this developmental stage compared to adulthood. Studies using the conditioned place preference (CPP) procedure have demonstrated that adolescent rats are more sensitive to the conditioned rewarding effects of subcutaneously administered nicotine compared to adult rats, whereas intravenous self-administration studies have not demonstrated consistent age differences in the reinforcing effects of nicotine. This study was designed to evaluate if intravenously administered nicotine has age-dependent conditioned rewarding effects. Using an unbiased CPP procedure, adolescent and adult male Wistar rats were conditioned with one of two intravenous doses of nicotine that are sufficient to maintain self-administration (0.03 or 0.06 mg/kg) or vehicle (saline) over a period of 8 conditioning trials (4 nicotine and 4 vehicle). Adolescent rats conditioned with 0.03 mg/kg nicotine demonstrated a significant CPP, whereas adult rats did not at either dose tested. After 8 extinction trials, reinstatement of the CPP was observed following a nicotine priming injection (0.15 mg/kg, s.c.) in adolescents that had previously been conditioned with 0.03 mg/kg nicotine; vehicle-treated rats did not show a significant preference for either compartment. The present data are consistent with previous CPP studies using subcutaneously administered nicotine and suggest that passively administered intravenous nicotine is more rewarding in adolescent compared to adult rats.
Shram
Megan J
MJ
Department of Neuroscience, Centre for Addiction and Mental Health, Toronto, Ontario, Canada M5S 2S1. shram.megan@kendle.com
Lê
Anh D
AD
D000367:Age Factors; D000704:Analysis of Variance; D000818:Animals; D001522:Behavior, Animal / Q000187:drug effects; D000697:Central Nervous System Stimulants / Q000008:administration & dosage; D002755:Choice Behavior / Q000187:drug effects; D003213:Conditioning, Psychological / Q000187:drug effects*; D004305:Dose-Response Relationship, Drug; D005108:Extinction, Psychological / Q000187:drug effects; D008297:Male; D009042:Motivation; D009043:Motor Activity / Q000187:drug effects; D009538:Nicotine / Q000008:administration & dosage*; D051381:Rats; D017208:Rats, Wistar; D012055:Reinforcement Schedule; D012201:Reward; D012646:Self Administration
D000697:Central Nervous System Stimulants; D009538:Nicotine