Introduction:

Many tasks used in the evaluation of learning and memory have stressful components. This makes it difficult to interpret the effects of stress on improvement, impairment or no effect on memory. It is considered that the object recognition task (RO) contain no stressful stimuli; therefore, it can be useful in the study of the effect of stress on memory.

Objective:

To evaluate the effect of restraint stress (R) (15 min) on acquisition and consolidation of memory in RO. In addition, the possible activation of the hypothalamic-pituitary-adrenal axis was evaluated as a consequence of the training in RO.

Methods:

Male Wistar rats assigned to four groups carried of the task of RO: two with R pre or post-training (R+RO, RO+R), another received corticosterone (C) intraperitoneally pre-training (C+RO) and one RO only (RO). Thereafter, they were immediately sacrificed and plasma C was quantified. To exclude the stressor effect of training in RO, C was measured in four groups: one intact (I), two trained in RO sacrificed 0 or 24 h later (ERO-0 and ERO-24) and another restricted 15 min (R15), sacrificed immediately after.

Results:

The R impaired the acquisition in the groups R+RO and RO+R; the concentration of C increased in R+RO and C+RO. In ERO-0 and R15, the plasma C increased.

Conclusions:

The pre-training R impaired memory. Training in RO increased the plasma C similar to R15 indicating the stressful nature of the task. The C injection did not modify memory.

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