How to improve lab mice's suitability as research models

Washington, December 9 (ANI): Experiments on mice conducted by Purdue University scientists have shown that the animals raised in cages may relieve stress with behaviours associated with their counterparts in the wild.

The researchers say that their findings indicate that allowing laboratory mice to express such behaviours may provide them with animals that act and respond more naturally, and, thereby, make research data more reliable.

Joseph Garner, assistant professor of animal sciences, highlighted the fact that lab mice lived in sterile environments controlled by humans, which could be stressful for them because they did not have much control.

"The perception of its ability to control stress has a bigger impact on the animal than does the stress itself. Chronic, uncontrollable stress changes animals, making them different than normal. This ultimately makes them less valid research subjects," he said.

The researcher said that it could be simply understood by thinking that when a person is cold, putting on a jacket or turning up the room temperature could relieve the stress. However, lacking the ability to make oneself warmer would cause further stress and make the person more likely to become ill, undergo physical changes and behave in ways that are not normal.

He said that the same was true for a mouse.

He and his university colleagues carried out a raft of experiments to test the ability of mice to control and select their preferred environment.

Describing their study in the journal Applied Animal Behavior Science, Garner said that his team "asked" mice which room temperatures they liked best.

The typical lab mouse is kept in a room at about 70 degrees Fahrenheit that, according to test results, was colder than the animals like.

The scientists placed mouse cages in custom-built water baths set to different temperatures, connected the cages with tunnels, and waited for the mice to "vote with their feet."

The mice chose which cages to spend time in, with the most popular choice being the warmest cage kept at 86 degrees Fahrenheit.

"They actually select different temperatures at different times of day and for different behaviours. So, while they preferred the warmer temperatures most of the time, it may not be possible to select a single preferred temperature for all mice," Garner said.

The researchers also tested the ability of lab animals to control their environment, and carried out an experiment to find out whether they could build better nests, a normal behavior for mice in the wild that is usually not seen in lab mice.

The animals were provided materials like those found in nature, and the caged mice instinctively built elaborate and complex nests very similar to those constructed by their wild counterparts.

According to the researchers, the nest building was both a form of stress relief and a way to enrich the quality of life for mice.

"Nest building is part of the 'mouseness of mouse,' meaning it is associated with normal mouse behaviour and helps define the species' unique characteristics," Garner said.

Garner said that allowing lab animals to perform behaviours that reduce stress might make them more normal research models.

"Ultimately, we want to know whether it could be beneficial for scientists to encourage behaviors such as nest building so that mice are less stressed, healthier, less anxious and more successful in their breeding," Garner said. (ANI)