Background Although mood-congruent memory (MCM), or the tendency to recall information consistent with one’s mood, is a robust phenomenon in human depression, to our knowledge, it has never been ...demonstrated in animals. Methods Mice were subjected to social isolation (SI) or crowding for 12 hours and had their depressive-like behaviour (evaluated by the forced swim, tail suspension, sucrose preference and splash tests) or their serum corticosterone concentrations evaluated. In addition, we determined the temporal forgetting curve of the plus-maze discriminative avoidance task (PM-DAT) and examined the effects of SI or crowding on memory retrieval in the PM-DAT. Finally, we verified the effects of metyrapone pretreatment on reinstatement of memory retrieval or on the increase of corticosterone levels induced by SI. Results Twelve hours of SI produced depressive-like behaviour, enhanced corticosterone concentration and reinstated retrieval of a forgotten discriminative aversive (i.e., negatively valenced) task. Depressive-like behaviour was critical for this facilitative effect of SI because 12 hours of crowding neither induced depressive-like behaviour nor enhanced retrieval, although it increased corticosterone levels at the same magnitude as SI. However, corticosterone increase was a necessary condition for MCM in mice, in that the corticosterone synthesis inhibitor metyrapone abolished SI-induced retrieval reinstatement. Limitations Our study did not investigate the effects of the social manipulations proposed here in a positively valenced task. Conclusion To our knowledge, the present paper provides the first evidence of MCM in animal models.
Abstract Background The purpose of this study was to: evaluate respiratory muscle strength and endurance in patients recently suffering myocardial infarction (MI) at inpatient period and investigate ...the effects of a home-based walking program on respiratory strength and endurance in post-MI patients with low risk. Methods Patients were randomized into: Usual Care Group (UCG) entailing regular care (n=23); and Intervention group (IG) entailing an outpatient home-based walking program (n=31). Healthy subjects gender and age-matched served as a control group for respiratory endurance variables. Respiratory muscle strength was evaluated through maximal inspiratory pressure (MIP) and endurance during the inpatient period, 15-days and 60-days after MI. Submaximal functional capacity was determined by 6-minute walk test (6MWT) at hospital discharge and 60 days after MI. Results Both groups showed impaired inspiratory muscle strength at hospital discharge. When compared with healthy subjects, post MI patients had worse respiratory muscle endurance pressure (PTHMAX= 73.02 ±8.40 vs 44.47±16.32, p<0.05) and time (Tlim= 324.1±12.2 vs 58.7±93.3, p<0.05). Only the IG showed a significant improvement in MIP and PTHMAX in 15 days and 60 days after MI (p<0.05). When comparing groups, the IG achieved higher values for MIP, PTHMAX and Tlim 15 and 60 days after MI (p<0.01). The 60-day assessment revealed that the 6MWT distance and level of physical activity was significantly higher in the IG compared to the UCG. Conclusion Low risk patients recently suffering a MI demonstrate impaired MIP and respiratory endurance compared to healthy subjects. A home-based walking program improved respiratory endurance and functional capacity.
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