Resumo

Introduction: Wild animals of several species change their behavior in the captivity condition. Conversely, animals maintained in environmental enrichment (EE) tend to have larger brain structures, higher learning ability, less stereotyped behaviors than those that developed in captivity conditions and present behavioral response most similar to wildlife animals. Objects: In view of these facts, we hypothesized that EE promotes improvement in ethological response in CF1 mice. To test this hypothesis, we exposed CF1 mice to EE from weaning for 8 weeks and evaluated the behavioral response in object recognition task (ORT). Material and Methods: Male albino CF1 mice (n=20) were weaned for 21 days and assigned randomly to standard or enriched housing immediately after weaning for 60 days. Recommendations for Animal Care and approved by the ethical committee from Universidade Federal do Rio Grande do Sul. All efforts were made to minimize the number of animals and their suffering. The ORT was performed in an apparatus consisting of a painted wood small chamber: 25 cm x 25 cm x 40 cm in dim lights. The objects were not known to have ethological significance for mice. Discrimination memory was evaluated trough time spent familiar object in test sessions and discrimination ratio that was expressed by the ratio TN/(TN+TF), (TN time spent exploring the novel object; TF time spent exploring familiar object), both in the training and test sessions performed 90 min and 24h after training session. The data of ORT was analyzed by Repeated Measures ANOVA. Results: A Repeated Measures ANOVA demonstrates the discrimination ratio increased linearly [F(1,14)= 50.77, p< 0.01], along the test sessions in both groups [F(2,28)= 25.62, p< 0.01]., without interaction between group* session [F(2,28)= 1.26, p> 0,05]. Repeated measures ANOVA revealed that both groups diminishes the total time spent in both objects [F(2,28)= 12.91, p< 0.01], without interaction between group*session [F(2,28)= 2.29, p> 0.05]. Also, tests of between-subjects effects generated in the Repeated measures ANOVA revealed that EE diminishes the time spent in both objects [F(1,14)= 58.8, p< 0.01]. The repeated measures ANOVA demonstrate that the mice diminishes the time spent in the familiar objects during the sessions [F(2,28)= 35.87, p< 0.01] and also revealed an interaction between groups*sessions, since EE presents continuous decreased time spent the familiar objects in test sessions [F(2,28)= 8.77, p< 0.01], this results, could indicate an increase in learning in the EE. Also, the tests of between-subjects effects generated in the Repeated measures ANOVA revealed that EE diminishes the time spent in familiar object [F(1,14)= 71.25, p< 0.01]. Discussion: Our findings indicate that EE group has a more propitious behavior, representing minor exposure to possible predator or rivals in this task and more efficient exploratory behavior in the four sessions of the ORT. Additionally the EE group present continuous learning in the second day in ORT. These findings could help to understand behavioral changes that occur with animals maintained in EE and corroborate to idea that EE improves the ethological response. Conclusion: The time spent in the exploration of new/ familiar objects increased linearly, along the test sessions in both groups. The EE group present continuous decreased time spent the familiar objects in test sessions.