title: Adolescent mice are less sensitive to the effects of acute nicotine on context pre-exposure than adults.
abstract: Adolescence is a critical developmental period associated with both increased vulnerability to substance abuse and maturation of certain brain regions important for learning and memory such as the hippocampus. In this study, we employed a hippocampus-dependent learning context pre-exposure facilitation effect (CPFE) paradigm in order to test the effects of acute nicotine on contextual processing during adolescence (post-natal day (PND) 38) and adulthood (PND 53). In Experiment 1, adolescent or adult C57BL6/J mice received either saline or one of three nicotine doses (0.09, 0.18, and 0.36mg/kg) prior to contextual pre-exposure and testing. Our results demonstrated that both adolescent and adult mice showed CPFE in the saline groups. However, adolescent mice only showed acute nicotine enhancement of CPFE with the highest nicotine dose whereas adult mice showed the enhancing effects of acute nicotine with all three doses. In Experiment 2, to determine if the lack of nicotine's effects on CPFE shown by adolescent mice is specific to the age when they are tested, mice were either given contextual pre-exposure during adolescence or adulthood and received immediate shock and testing during adulthood after a 15day delay. We found that both adolescent and adult mice showed CPFE in the saline groups when tested during adulthood. However, like Experiment 1, mice that received contextual pre-exposure during adolescence did not show acute nicotine enhancement except at the highest dose (0.36mg/kg) whereas both low (0.09mg/kg) and high (0.36mg/kg) doses enhanced CPFE in adult mice. Finally, we showed that the enhanced freezing response found with 0.36mg/kg nicotine in the 15-day experiment may be a result of decreased locomotor activity as mice that received this dose of nicotine traveled shorter distances in an open field paradigm. Overall, our results indicate that while adolescent mice showed normal contextual processing when tested both during adolescence and adulthood, they are less sensitive to the enhancing effects of nicotine on contextual processing.
authors.affiliation: Department of Psychology, Neuroscience Program, Weiss Hall, Temple University, 1701 N. 13th St, Philadelphia, PA 19122, USA. Electronic address: munir.kutlu@temple.edu.
authors.forename: Munir Gunes
authors.initials: MG
authors.lastname: Kutlu
authors.affiliation: Department of Psychology, Neuroscience Program, Weiss Hall, Temple University, 1701 N. 13th St, Philadelphia, PA 19122, USA.
authors.forename: David C
authors.initials: DC
authors.lastname: Braak
authors.affiliation: Department of Psychology, Neuroscience Program, Weiss Hall, Temple University, 1701 N. 13th St, Philadelphia, PA 19122, USA.
authors.forename: Jessica M
authors.initials: JM
authors.lastname: Tumolo
authors.affiliation: Department of Psychology, Neuroscience Program, Weiss Hall, Temple University, 1701 N. 13th St, Philadelphia, PA 19122, USA.
authors.forename: Thomas J
authors.initials: TJ
authors.lastname: Gould
mesh_terms: D000375:Aging / Q000187:drug effects*; D000818:Animals; D003213:Conditioning, Psychological / Q000187:drug effects*; D004305:Dose-Response Relationship, Drug; D004597:Electroshock; D005106:Exploratory Behavior / Q000187:drug effects; D005239:Fear / Q000187:drug effects*; D046352:Freezing Reaction, Cataleptic / Q000187:drug effects; D008810:Mice, Inbred C57BL; D023421:Models, Animal; D009043:Motor Activity / Q000187:drug effects; D009538:Nicotine / Q000008:administration & dosage*; D018722:Nicotinic Agonists / Q000008:administration & dosage*; D011581:Psychological Tests
chemical_list: D018722:Nicotinic Agonists; D009538:Nicotine
keywords: Adolescence; Context; Fear conditioning; Nicotine