title: Individual differences in activity predict locomotor activity and conditioned place preference to amphetamine in both adolescent and adult rats.
abstract: Individual and developmental differences in novelty seeking have been implicated in differential sensitivity to psychostimulants in rodents, but findings are mixed. The extent to which age differences in activity in a novel arena depended on test duration was examined by comparing adolescent and adult rats after 5 and after 60 min of testing (session 1). Rats were tested again after amphetamine or saline administration 24h later (session 2) to examine whether activity in a novel arena predicts sensitivity to locomotor-activating effects of amphetamine. Data from two experiments were used to examine consistency of the findings. Only activity in 60 min sessions produced a consistent age difference (adolescent<adult) and predicted activity after amphetamine in session 2. Session 1 activity also predicted saline activity in session 2, indicating that individual differences in activity is a stable trait. A third data set was used to determine whether general (saline) and amphetamine-induced activity predicted magnitude of conditioned place preference (CPP) in late-adolescent and adult rats. Age was not a significant predictor, but CPP was positively associated with amphetamine activity and negatively associated with saline activity. Thus, in contrast to enhanced psychostimulant sensitivity in high novelty-seekers, rats higher in general activity are less sensitive to amphetamine conditioned place preference.
authors.affiliation: Department of Psychology and Neuroscience Program, Brock University, St. Catharines, ON, Canada.
authors.forename: Iva Z
authors.initials: IZ
authors.lastname: Mathews
authors.forename: Mark D
authors.initials: MD
authors.lastname: Morrissey
authors.forename: Cheryl M
authors.initials: CM
authors.lastname: McCormick
mesh_terms: D000375:Aging; D000662:Amphetamines / Q000494:pharmacology*; D000818:Animals; D003214:Conditioning, Classical; D008124:Locomotion; D008297:Male; D051381:Rats; D020318:Rats, Long-Evans
chemical_list: D000662:Amphetamines