title: A facilitative role for corticosterone in the acquisition of a spatial task under moderate stress.
abstract: Emotionally charged experiences alter memory storage via the activation of hormonal systems. Previously, we have shown that compared with rats trained for a massed spatial learning task in the water maze in warm water (25 degrees C), animals that were trained in cold water (19 degrees C) performed better and showed higher levels of the stress hormone corticosterone. Here, we examined whether manipulating the levels of corticosterone can determine the strength of spatial information acquisition and retention. Rats were injected with metyrapone (25, 50, and 75 mg/kg, i.p.) or with corticosterone (10 and 25 mg/kg, i.p.) and trained in a massed spatial task in either cold (19 degrees C) or warm (25 degrees C) water. We found that whereas animals injected with vehicle performed well in the spatial task in cold water (moderate stress), rats injected with the intermediate metyrapone dose showed impairment in performance. Moreover, whereas animals injected with vehicle on average did not perform well in warm water (mild stress), rats injected with the lower corticosterone dose showed improvement in performance in warm water. These two mirror experiments of corticosterone blockade and enhancement strongly suggest that corticosterone is instrumental in the acquisition and retention of the spatial learning task.
authors.affiliation: Department of Psychology and the Brain and Behavior Research Center, University of Haifa, Haifa 31905, Israel.
authors.forename: Irit
authors.initials: I
authors.lastname: Akirav
authors.forename: Maya
authors.initials: M
authors.lastname: Kozenicky
authors.forename: Dadi
authors.initials: D
authors.lastname: Tal
authors.forename: Carmen
authors.initials: C
authors.lastname: Sandi
authors.forename: Cesar
authors.initials: C
authors.lastname: Venero
authors.forename: Gal
authors.initials: G
authors.lastname: Richter-Levin
mesh_terms: D000818:Animals; D001831:Body Temperature / Q000502:physiology; D003345:Corticosterone / Q000097:blood*; D004791:Enzyme Inhibitors / Q000494:pharmacology*; D008297:Male; D018782:Maze Learning / Q000187:drug effects* / Q000502:physiology; D008797:Metyrapone / Q000494:pharmacology*; D051381:Rats; D017208:Rats, Wistar; D013028:Space Perception / Q000187:drug effects* / Q000502:physiology; D013312:Stress, Physiological / Q000503:physiopathology*; D013550:Swimming / Q000502:physiology; D013696:Temperature
chemical_list: D004791:Enzyme Inhibitors; D003345:Corticosterone; D008797:Metyrapone