title: Immediate early gene expression reveals interactions between social and nicotine rewards on brain activity in adolescent male rats.
abstract: Smoking initiation predominantly occurs during adolescence, often in the presence of peers. Therefore, understanding the neural mechanisms underlying the rewarding effects of nicotine and social stimuli is vital. Using the conditioned place preference (CPP) procedure, we measured immediate early gene (IEG) expression in animals following exposure either to a reward-conditioned environment or to the unconditioned stimuli (US). Adolescent, male rats were assigned to the following CPP US conditions: (1) Saline+Isolated, (2) Nicotine+Isolated, (3) Saline+Social, or (4) Nicotine+Social. For Experiment 1, brain tissue was collected 90min following the CPP expression test and processed for Fos immunohistochemistry. We found that rats conditioned with nicotine with or without a social partner exhibited CPP; however, we found no group differences in Fos expression in any brain region analyzed, with the exception of the nucleus accumbens core that exhibited a social-induced attenuation in Fos expression. For Experiment 2, brain tissue was collected 90min following US exposure during the last conditioning session. We found social reward-induced increases in IEG expression in striatal and amydalar subregions. In contrast, nicotine reduced IEG expression in prefrontal and striatal subregions. Reward interactions were also found in the dorsolateral striatum, basolateral amygdala, and ventral tegmental area where nicotine alone attenuated IEG expression and social reward reversed this effect. These results suggest that in general social rewards enhance, whereas nicotine attenuates, activation of mesocorticolimbic regions; however, the rewards given together interact to enhance activation in some regions. The findings contribute to knowledge of how a social environment influences nicotine effects.
authors.affiliation: Department of Psychology, Arizona State University, Tempe, AZ 85287-4501, United States; School of Life Sciences, Arizona State University, Tempe, AZ 85287-4501, United States.
authors.forename: Ryan M
authors.initials: RM
authors.lastname: Bastle
authors.affiliation: Department of Psychology, Arizona State University, Tempe, AZ 85287-4501, United States.
authors.forename: Natalie A
authors.initials: NA
authors.lastname: Peartree
authors.affiliation: School of Life Sciences, Arizona State University, Tempe, AZ 85287-4501, United States.
authors.forename: Julianna
authors.initials: J
authors.lastname: Goenaga
authors.affiliation: School of Life Sciences, Arizona State University, Tempe, AZ 85287-4501, United States.
authors.forename: Kayla N
authors.initials: KN
authors.lastname: Hatch
authors.affiliation: Department of Psychology, Arizona State University, Tempe, AZ 85287-4501, United States.
authors.forename: Angela
authors.initials: A
authors.lastname: Henricks
authors.affiliation: School of Life Sciences, Arizona State University, Tempe, AZ 85287-4501, United States.
authors.forename: Samantha
authors.initials: S
authors.lastname: Scott
authors.affiliation: Department of Psychology, Arizona State University, Tempe, AZ 85287-4501, United States.
authors.forename: Lauren E
authors.initials: LE
authors.lastname: Hood
authors.affiliation: Department of Psychology, Arizona State University, Tempe, AZ 85287-4501, United States; School of Life Sciences, Arizona State University, Tempe, AZ 85287-4501, United States. Electronic address: Janet.Neisewander@asu.edu.
authors.forename: Janet L
authors.initials: JL
authors.lastname: Neisewander
mesh_terms: D000375:Aging; D000818:Animals; D001921:Brain / Q000187:drug effects*; D003213:Conditioning, Psychological / Q000187:drug effects; D005108:Extinction, Psychological / Q000187:drug effects; D015870:Gene Expression / Q000187:drug effects*; D017781:Genes, Immediate-Early / Q000187:drug effects*; D008297:Male; D009538:Nicotine / Q000008:administration & dosage / Q000494:pharmacology*; D018722:Nicotinic Agonists / Q000494:pharmacology; D016760:Proto-Oncogene Proteins c-fos / Q000378:metabolism; D017207:Rats, Sprague-Dawley; D012201:Reward; D012919:Social Behavior; D012931:Social Environment
chemical_list: D018722:Nicotinic Agonists; D016760:Proto-Oncogene Proteins c-fos; D009538:Nicotine
keywords: Addiction; Conditioned place preference; Drug; Fos; Immunohistochemistry; Zif268