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A number of experiments have shown that physical exercise improves acquisition and retention for a variety of learning tasks in rodents. Most of these works have been conducted with tasks associated with a considerable level of stress, physical effort and/or food deprivation that might interact with exercise, thus hindering the interpretation of the results. On the other hand, it is well established that post-training epinephrine is able to facilitate memory consolidation, but only a few works have studied its effect on the process of acquisition. The present work was aimed at studying whether 17 days of voluntary physical exercise (running wheels) and/or post-training epinephrine (0.01 or 0.05 mg/kg) could improve the acquisition of a spatial task in the Barnes maze, and whether the combination of the two treatments have additive effects. Our results showed that exercise improved acquisition, and 0.01 mg/kg of epinephrine tended to enhance it, by reducing the distance needed to find the escape hole. The combination of both treatments failed to further improve the acquisition level. We concluded that both treatments exerted their effect on acquisition by enhancing the process of learning itself, and that exercise is able to improve acquisition even using tasks with a low level of stress and physical effort., (Copyright © 2013 Elsevier B.V. All rights reserved.)

The present work examined whether post-training systemic epinephrine (EPI) is able to modulate short-term (3h) and long-term (24 h and 48 h) memory of standard object recognition, as well as long-term (24 h) memory of separate "what" (object identity) and "where" (object location) components of object recognition. Although object recognition training is associated to low arousal levels, all the animals received habituation to the training box in order to further reduce emotional arousal. Post-training EPI improved long-term (24 h and 48 h), but not short-term (3 h), memory in the standard object recognition task, as well as 24 h memory for both object identity and object location. These data indicate that post-training epinephrine: (1) facilitates long-term memory for standard object recognition; (2) exerts separate facilitatory effects on "what" (object identity) and "where" (object location) components of object recognition; and (3) is capable of improving memory for a low arousing task even in highly habituated rats.

We studied whether posttraining epinephrine accelerates the process of acquisition, and whether this effect leads to an enduring high level of performance on a long-term memory test (20 days). Rats were submitted to daily massed (30 trials) two-way active avoidance conditioning sessions followed by systemic epinephrine (0.01 mg/kg) or vehicle, until achieving a learning criterion (80% avoidances in one single session, maximum 14 sessions). By the sixth session, 78% of the animals with posttraining epinephrine attained the learning criterion compared to only the 23% of the rats in the vehicle group. Considering the whole acquisition phase, all the epinephrine treated animals, but only 66.67% in the vehicle group, reached the criterion. On the retention test, both groups maintained the level of performance reached at the end of the acquisition phase. We conclude that epinephrine accelerates the process of acquisition by enhancing memory consolidation, and that this effect might be especially useful in high demanding learning tasks, or for animals with low learning capacities.