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Male mouse aggression as a pharmacologic model
Abstract:
At 5 to 8 months of age the fighting and tail-rattling of male Marsh mice during paired confrontations was significantly greater for isolated than for mice prehoused in groups of males or in groups of one male with females. The differences were not significant for treatment effects tested in a similar manner with mice 11 to 12 months of age. At 5 months of age, mounting behavior of pregrouped males on paired confrontation was significantly less than that of isolated males. Paper towels instead of pine shavings for bedding abolished test-fighting for isolated mice. In any model with randomly sampled groups, an inherently highly aggressive mouse (killer) required to be eliminated from the grouped series, is not detected in the isolated series. These considerations challenge the use of isolated male mice as a pharmacologic model for evaluating behavior-modifying drugs. A four-fold difference in the area of prehousing cages of isolated males did not influence aggressive behavior. Fights correlated with tail-rattling; r equals 0.93 over the 14 series studied.
Insights
Isolated male mice exhibit higher aggression, challenging their use in drug studies. Housing conditions significantly impact aggressive behaviors in Marsh mice, affecting research validity.
Area of Science:
- Ethology
- Neuroscience
- Pharmacology
Background:
- Social housing and environmental enrichment can modulate aggressive behaviors in rodents.
- The validity of animal models in pharmacological research depends on their ability to accurately reflect human conditions.
Purpose of the Study:
- To investigate the impact of housing conditions on aggressive behaviors in male Marsh mice.
- To evaluate the suitability of isolated male mice as a model for drug-induced behavioral modification studies.
Main Methods:
- Paired confrontations were used to assess fighting and tail-rattling in male Marsh mice of different ages (5-8 months and 11-12 months).
- Mice were housed individually or in groups (male-only or male-female).
- Bedding type (paper towels vs. pine shavings) and cage size were varied.
Main Results:
- Younger isolated male mice (5-8 months) displayed significantly more fighting and tail-rattling than grouped mice.
- Mounting behavior was also higher in isolated young males.
- Aggression in isolated mice was abolished by using paper towels instead of pine shavings for bedding.
- A highly aggressive 'killer' mouse was not detected in isolated groups, unlike in grouped series.
Conclusions:
- Housing conditions, particularly isolation, significantly influence aggressive behaviors in young male Marsh mice.
- The use of isolated male mice as a pharmacologic model for behavior-modifying drugs is questionable due to these environmental effects.
- Bedding type is a critical factor that can abolish aggression in isolated mice, further complicating their use as a standardized model.