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Maudsley reactive and nonreactive rats in the forced swim test: comparison in fresh water and soiled water
E L Abel1, H J Altman, R L Commissaris
1Department of Obstetrics/Gynecology, Wayne State University, Detroit, MI 48201.
Abstract:
Maudsley reactive (MR) and nonreactive (MNRA) and Sprague-Dawley (SD) male rats were tested for their immobility response in the forced swim test when the water was fresh or soiled by a rat of the same or other strain. For all strains, rats tested in soiled water were less immobile than rats in fresh water. The three strains did not differ as producers of soiling substance, but did differ in their response to it. The MR strain was least responsive, whereas the MNRA and SD did not differ from one another. These results support a previous study suggesting that MR rats are more immobile than MNRA rats in the forced swim test. The interpretation of these findings regarding the use of the Maudsley rat strains as an animal model for studying anxiety and/or depression is discussed.
Insights
Maudsley reactive (MR) and nonreactive (MNRA) rats, along with Sprague-Dawley (SD) rats, showed reduced immobility in soiled water during the forced swim test. MR rats were least responsive to soiled water, impacting their use as anxiety and depression models.
Area of Science:
- Behavioral Neuroscience
- Animal Models
- Psychopharmacology
Background:
- The forced swim test (FST) is a widely used behavioral paradigm to assess depression and anxiety-like behaviors in rodents.
- Maudsley reactive (MR) and Maudsley nonreactive (MNRA) rat strains exhibit differential behavioral responses, making them valuable for studying emotionality.
- Previous research suggests MR rats display greater immobility in the FST compared to MNRA rats.
Purpose of the Study:
- To investigate the influence of soiled water, a potential stressor, on immobility in MR, MNRA, and Sprague-Dawley (SD) rat strains.
- To determine if the strains differ in their production of or response to the soiling substance.
- To further evaluate the utility of MR and MNRA rat strains as models for anxiety and depression research.
Main Methods:
- Male rats from MR, MNRA, and SD strains were subjected to the FST in either fresh or soiled water.
- Water was soiled by a conspecific or a rat from a different strain.
- Immobility duration was measured as the primary outcome in the FST.
Main Results:
- Across all strains, rats tested in soiled water exhibited significantly less immobility compared to those in fresh water.
- No significant differences were found among the three strains in their production of the soiling substance.
- The MR strain demonstrated the least behavioral response to the soiled water, while MNRA and SD strains showed similar responses.
Conclusions:
- Soiled water reduces immobility in the FST for MR, MNRA, and SD rats, suggesting an environmental modulation of behavioral despair.
- The differential response of MR rats to soiled water warrants further investigation regarding their suitability as a model for anxiety and depression.
- These findings highlight the importance of environmental factors in interpreting FST results and refining animal models for psychiatric research.