title: Potentiation of the expression of cocaine-induced sensitization by a conditioned stressor.
abstract: Repeated exposures to physical stressors cross-sensitize to the locomotor activating effects of psychostimulants in rodents. In the present study, we examined the effect of a conditioned stressor on expression of cocaine-induced sensitization in rats. We determined whether a mint odor cue previously paired with footshock stress (FS) would elicit a sensitized locomotor response in cocaine pre-exposed rats. Rats were given once daily injections of cocaine (30 mg/kg, i.p.) or saline for 6 days in activity monitoring chambers. Subsequently, and in a different and distinct context, equal numbers of rats in each drug condition were exposed to 10 min of brief, intermittent FS or no FS, either in the presence or absence of the mint odor cue. Upon re-exposure to the activity chambers (in which cocaine exposures had been given), all rats previously exposed to cocaine showed robust conditioned locomotion. In response to a cocaine challenge (10 mg/kg, i.p.), cocaine relative to saline pre-exposed rats showed a sensitized locomotor response. Finally, in those cocaine pre-exposed rats that had been given prior odor-FS pairings, concurrent delivery of the cocaine challenge and presentation of the odor cue markedly potentiated the expression of sensitization. To our knowledge, this is the first report of a facilitation of cocaine-induced locomotor sensitization by a conditioned stressor.
authors.affiliation: Department of Cell and Systems Biology, University of Toronto, 1265 Military Trail, Toronto, ON M1C 1A4, Canada.
authors.forename: Aya
authors.initials: A
authors.lastname: Sasaki
authors.affiliation: Department of Psychology, University of Toronto Scarborough, 1265 Military Trail, Toronto, ON M1C 1A4, Canada.
authors.forename: Shathveekan
authors.initials: S
authors.lastname: Sivanathan
authors.affiliation: Department of Psychology, University of Toronto Scarborough, 1265 Military Trail, Toronto, ON M1C 1A4, Canada.
authors.forename: Atif
authors.initials: A
authors.lastname: Hussain
authors.affiliation: Department of Psychology, University of Toronto Scarborough, 1265 Military Trail, Toronto, ON M1C 1A4, Canada.
authors.forename: Purathani
authors.initials: P
authors.lastname: Shanmuganathan
authors.affiliation: Department of Psychology, University of Toronto Scarborough, 1265 Military Trail, Toronto, ON M1C 1A4, Canada.
authors.forename: Archana
authors.initials: A
authors.lastname: Sivakumaran
authors.affiliation: Department of Psychology, University of Toronto Scarborough, 1265 Military Trail, Toronto, ON M1C 1A4, Canada; Department of Cell and Systems Biology, University of Toronto, 1265 Military Trail, Toronto, ON M1C 1A4, Canada. Electronic address: erb@utsc.utoronto.ca.
authors.forename: Suzanne
authors.initials: S
authors.lastname: Erb
mesh_terms: D000818:Animals; D001522:Behavior, Animal / Q000187:drug effects*; D059333:Central Nervous System Sensitization / Q000187:drug effects*; D000697:Central Nervous System Stimulants / Q000494:pharmacology*; D003042:Cocaine / Q000494:pharmacology*; D009043:Motor Activity / Q000187:drug effects*; D017208:Rats, Wistar; D013312:Stress, Physiological / Q000187:drug effects*
chemical_list: D000697:Central Nervous System Stimulants; D003042:Cocaine
keywords: Cocaine Challenge; Conditioned stressor; Footshock stress; Locomotor sensitization; Olfactory conditioning; Rodent