title: Mild acute stress reactivates memory of a discriminative avoidance task in mice.
abstract: Previous studies have demonstrated that stress or glucocorticoids impair the retrieval of spatial memory in rodents and declarative memory in humans. However, the effects on memory retrieval of stress introduced a long time after learning have not been well studied. We investigated whether a mild, extrinsic stressor (1-s 0.1 or 0.3 mA foot shock) would reactivate low baseline retrieval of an aversive memory [the plus-maze discriminative avoidance task (PM-DAT)] and if it would be modulated by glucocorticoids. In Experiment 1, male Swiss mice received pre-test foot shock (n = 10 mice/group) 7 days after training and just before testing. A time-retrieval curve for low baseline retrieval for the subsequent experiments was also determined (Experiment 2, n = 10 mice/group). We investigated if pre-test foot shock could modify corticosterone release (Experiment 3, n = 8-9 mice/group) and reinstate retrieval in the PM-DAT (Experiment 4, n = 15 mice/group). The effects of metyrapone (100 mg/kg) on retrieval reinstatement (Experiment 5, n = 15 mice/group) and serum corticosterone enhancement (Experiments 6, n = 7-9 mice/group) induced by foot shock were analyzed. Finally, the effects of foot shock itself on PM-DAT exploration were verified (Experiment 7, n = 10 mice/group). We demonstrated here that foot shock reinstated the retrieval of a low baseline, discriminative avoidance task 30 (but not 7) days after training. This facilitative effect was not dependent on corticosterone secretion because metyrapone abolished the enhancement of corticosterone concentration but did not reverse the stress-induced reinstatement of retrieval.
authors.affiliation: Departamento de Farmacologia, Universidade Federal de São Paulo, São Paulo, Brasil.
authors.forename: André L
authors.initials: AL
authors.lastname: Takatsu-Coleman
authors.forename: Camilla L
authors.initials: CL
authors.lastname: Patti
authors.forename: Karina A
authors.initials: KA
authors.lastname: Zanin
authors.forename: Leandro
authors.initials: L
authors.lastname: Sanday
authors.forename: Adriano
authors.initials: A
authors.lastname: Zager
authors.forename: Rita C
authors.initials: RC
authors.lastname: Carvalho
authors.forename: Monica L
authors.initials: ML
authors.lastname: Andersen
authors.forename: Sergio
authors.initials: S
authors.lastname: Tufik
authors.forename: Roberto
authors.initials: R
authors.lastname: Frussa-Filho
mesh_terms: D000818:Animals; D001362:Avoidance Learning / Q000187:drug effects; D001522:Behavior, Animal / Q000187:drug effects; D003345:Corticosterone / Q000097:blood; D004193:Discrimination Learning / Q000187:drug effects; D004558:Electric Stimulation; D004791:Enzyme Inhibitors / Q000494:pharmacology; D008297:Male; D018782:Maze Learning / Q000187:drug effects; D011939:Mental Recall / Q000187:drug effects; D051379:Mice; D011725:Pyridines / Q000494:pharmacology; D013252:Steroid 11-beta-Hydroxylase / Q000037:antagonists & inhibitors / Q000378:metabolism; D013315:Stress, Psychological / Q000097:blood / Q000523:psychology*; D013997:Time Factors
chemical_list: D004791:Enzyme Inhibitors; D011725:Pyridines; C013109:metapyrone; D013252:Steroid 11-beta-Hydroxylase; D003345:Corticosterone