title: Age-dependent differences in the strength and persistence of psychostimulant-induced conditioned activity in rats: effects of a single environment-cocaine pairing.
abstract: The aim of the present study was to determine the strength and persistence of cocaine-induced conditioned activity in young and adult rats. A one-trial protocol has proven useful for studying the ontogeny of psychostimulant-induced behavioral sensitization; therefore, a similar procedure was used to examine conditioned activity. On postnatal day (PD) 19 or PD 80, rats were injected with saline or cocaine in either a novel test chamber or the home cage. After various drug abstinence intervals (1-21 days), rats were injected with saline and returned to the test chamber, where conditioned activity was assessed. In a separate experiment, we examined whether cocaine-induced conditioned activity was a consequence of Pavlovian conditioning or a failure to habituate to the test environment. The results indicated that adult rats showed strong one-trial conditioned activity that persisted for at least 21 days, whereas young rats did not show a conditioned locomotor response. The conditioned activity shown by adult rats did not result from a failure to habituate to the cocaine-paired environment. These results indicate that cocaine-paired contextual stimuli differentially affect behavior depending on the age of the animal. The data obtained from adult rats have potential translational relevance for humans because a single environment-drug pairing caused long-term alterations in behavior.
authors.affiliation: Department of Psychology, 5500 University Parkway, California State University, San Bernardino, California, USA.
authors.forename: Sanders A
authors.initials: SA
authors.lastname: McDougall
authors.forename: Joseph A
authors.initials: JA
authors.lastname: Pipkin
authors.forename: Taleen
authors.initials: T
authors.lastname: Der-Ghazarian
authors.forename: Anthony M
authors.initials: AM
authors.lastname: Cortez
authors.forename: Arnold
authors.initials: A
authors.lastname: Gutierrez
authors.forename: Ryan J
authors.initials: RJ
authors.lastname: Lee
authors.forename: Sandra
authors.initials: S
authors.lastname: Carbajal
authors.forename: Alena
authors.initials: A
authors.lastname: Mohd-Yusof
mesh_terms: D000367:Age Factors; D000818:Animals; D001522:Behavior, Animal / Q000187:drug effects*; D000697:Central Nervous System Stimulants / Q000008:administration & dosage / Q000494:pharmacology*; D003042:Cocaine / Q000008:administration & dosage / Q000494:pharmacology*; D003214:Conditioning, Classical / Q000187:drug effects*; D004777:Environment; D006185:Habituation, Psychophysiologic; D008297:Male; D051381:Rats; D017207:Rats, Sprague-Dawley; D013997:Time Factors
chemical_list: D000697:Central Nervous System Stimulants; D003042:Cocaine