Making mice comfy leads to better science, researcher says
Nine out of 10 drugs successfully tested in mice and other animal models ultimately fail to work in people, and one reason may be traced back to a common fact of life for laboratory mice: they're cold, according to a researcher at the Stanford University School of Medicine.
Laboratory mice, which account for the vast majority of animal research subjects, are routinely housed in chilly conditions, which may affect their well-being as well as the outcome of research studies, said Joseph Garner, PhD, associate professor of comparative medicine.
"If you want to design a drug that will help a patient in the hospital, you cannot reasonably do that in animals that are cold-stressed and are compensating with an elevated metabolic rate," Garner said. "This will change all aspects of their physiology such as how fast the liver breaks down a drug which can't help but increase the chance that a drug will behave differently in mice and in humans."
In a new study, Garner and his colleagues report finding an easy solution to the problem: Simply provide the animals with the proper materials, and they'll build a cozy nest that allows them to naturally regulate their temperatures to a comfortable level. These thermally content mice would be more physiologically comparable to humans and thus might serve as more meaningful research subjects, Garner said.
"Why not let them do what they do in the wild, which is build nests? Mice can happily infest a meat freezer, with temperatures far below zero, but they survive and breed because they build these wonderful nests," he said.
The study, part of nearly seven years of work with mouse nesting behavior, is the first to "ask" mice to rate the value of nesting material in terms of temperature savings, which is an important first step in setting standards for nesting material, said Garner, whose work has focused on the well-being of the mouse. He is the senior author of the study, which will be published online March 30 in PLoS ONE.
Mice, which Garner calls "one of the most fantastic animals on Earth," have evolved in the same environment as humans for thousands of years, making them remarkably adaptable, able to live virtually anywhere. For that reason, they make excellent research subjects, with hundreds of millions of them populating laboratories around the world.
Given the option, mice gravitate to temperatures of between 30 and 32 degrees Celsius (the equivalent of about 86 and 90 degrees Fahrenheit). But based on federal regulations, U.S. research laboratories are routinely kept on the cold side between 20 to 24 degrees C. There can be advantages to these cold temperatures. For instance, mice have aggressive tendencies that are suppressed in cooler climes. Female mice also lactate better in cooler temperatures, though their pups don't do as well in the cold.
When kept in temperatures toward the low end of this scale between about 18 and 20 degrees C (64-68 degrees F) the mice begin to show changes in immune function and their growth may be retarded. "So we're housing them right at that threshold," Garner said. "That means the mice may be compromised physiologically, potentially affecting research results."
Simply raising the temperature in the lab isn't an option, not least because the mice would then become unmanageably aggressive, he said. Rather, Garner and his colleagues looked to other options in their study, which involved 36 male and 36 female mice of three common strains. The researchers created sets of two cages linked by a small tube so the mice could move between them. One cage in each set was maintained at a chilly 20 degrees C (68 degrees F) and was equipped with varying quantities of shredded paper, which the animals could use to construct nests for shelter and warmth. The other cage was kept at one of six temperatures: 20, 23, 26, 29, 32 or 35 degrees C (68, 73, 79, 84, 90 or 95 F), but without nesting material.
The mice then had the choice of staying put and tolerating the cold, choosing a balmier cage, eating more to add fat and elevate metabolic rate, or building a nest.
Each strain and sex had slightly different preferences, the researchers found. None was content to simply sit out the cold, either moving to a toastier location, if available, or building elaborate, dome-like nests to warm themselves. The more nest-building material they had, the more they were willing to settle for a cooler clime, as the nests served to temper the chill, the researchers found.
In fact, the nest-building drive was so strong that the mice often would spend hours collecting strands of paper, bit by bit, from the chilliest cage and then transporting it to a more comfortable spot in another cage to build a sturdy little home.
Garner said these mice decided they wanted to have it all, choosing a warm spot and building a nest as well. "Naughty little rascals" is how he described them. "They would go on holiday somewhere warm AND take their nest with them," he said. "Some people like to take a pillow on holiday and some don't. These mice were packing their own pillow."
The fact that some mice moved nesting material to the warmer cage means that the nests serve a function beyond warmth, argued Garner, perhaps providing physical comfort, or a form of protection that decreases the animals' anxiety and stress levels.
The nest-building mice tended to eat less, as they didn't need the extra calories to satisfy their higher metabolic demands, the researchers found. In general, the females preferred warmer temperatures than the males by about 5 degrees: they are smaller and have less fat to generate heat.
The researchers concluded that the mice could manage with 6 grams of nesting material but sometimes could use as much as 10 grams, suggesting the larger amount be supplied routinely in research labs.
Another benefit of the nests is that they facilitate researchers' work with the mice it's easier to pick them up as well as observe them. "The shape of the nest tells an experienced person whether the animals are too hot or too cold, whether they are sick or whether they are about to give birth," Garner said. "Once you learn how to 'speak mouse nest,' the nest is a wonderful tool that anyone can use to assess the general state of the mouse."
Provided by Stanford University Medical Center
- Stress relief: Lab mice that exercise control may be more normal Dec 08, 2008 | not rated yet | 0
- Mice and men should have more in common in clinical trials Mar 30, 2009 | not rated yet | 0
- Menthol receptor also important in detecting cold temperatures Jun 07, 2007 | not rated yet | 0
- Intentional variation increases result validity in mouse testing Mar 09, 2010 | not rated yet | 0
- Serotonin plays active role in the sexual preference of mice Mar 25, 2011 | not rated yet | 0
- Motion perception revisited: High Phi effect challenges established motion perception assumptions Apr 23, 2013 | 3 / 5 (2) | 2
- Anything you can do I can do better: Neuromolecular foundations of the superiority illusion (Update) Apr 02, 2013 | 4.5 / 5 (11) | 5
- The visual system as economist: Neural resource allocation in visual adaptation Mar 30, 2013 | 5 / 5 (2) | 9
- Separate lives: Neuronal and organismal lifespans decoupled Mar 27, 2013 | 4.9 / 5 (8) | 0
- Sizing things up: The evolutionary neurobiology of scale invariance Feb 28, 2013 | 4.8 / 5 (10) | 14
Why is zone 1 in liver more prone to ischemic injury?
17 hours ago Hi, Is it because around central vein, there is only deoxygenated blood from the vein where as in the periphery there is hepatic artery. Also why...
How can there be villous adenoma in colon, if there are no villi there
May 22, 2013 As title suggest. Thanks :smile:
How can there be a term called "intestinal metaplasia" of stomach
May 21, 2013 Hello everyone, Ok Stomach's normal epithelium is simple columnar, now in intestinal type of adenocarcinoma of stomach it undergoes "intestinal...
Pressure-volume curve: Elastic Recoil Pressure don't make sense
May 18, 2013 From pressure-volume curve of the lung and chest wall (attached photo), I don't understand why would the elastic recoil pressure of the lung is...
If you became brain-dead, would you want them to pull the plug?
May 17, 2013 I'd want the rest of me to stay alive. Sure it's a lousy way to live but it beats being all-the-way dead. Maybe if I make it 20 years they'll...
MRI bill question
May 15, 2013 Dear PFers, The hospital gave us a $12k bill for one MRI (head with contrast). The people I talked to at the hospital tell me that they do not...
- More from Physics Forums - Medical Sciences
More news stories
By discovering the new mechanism by which estrogen suppresses lipid synthesis in the liver, UC Irvine endocrinologists have revealed a potential new approach toward treating certain liver diseases.
Medical research 5 hours ago | not rated yet | 0 |
Aortic arch pulse wave velocity, a measure of arterial stiffness, is a strong independent predictor of disease of the vessels that supply blood to the brain, according to a new study published in the June issue the journal ...
Medical research 5 hours ago | not rated yet | 0
Since the discovery of Prontosil in 1932, sulfonamide antibiotics have been used to combat a wide spectrum of bacterial infections, from acne to chlamydia and pneumonia. However, their side effects can include serious neurological ...
Medical research 7 hours ago | not rated yet | 0 |
Scientists at the National Institutes of Health report they have discovered in mouse studies that a small molecule released in the spinal cord triggers a process that is later experienced in the brain as ...
Medical research 7 hours ago | 5 / 5 (2) | 0 |
Spanish researchers have discovered that the daily clearance of neutrophils from the body stimulates the release of hematopoietic stem cells from the bone marrow into the bloodstream, according to a report published today ...
Medical research 8 hours ago | 5 / 5 (2) | 0
(HealthDay)—Type 2 diabetes is more aggressive in children than adults, with signs of serious complications seen just a few years after diagnosis, new research finds.
42 minutes ago | not rated yet | 0
(Medical Xpress)—Regulating the distribution of power in neurons is done by a system that makes the national electric grid look simple by comparison. Each neuron has several thousand mitochondria confined ...
3 hours ago | 4.7 / 5 (3) | 0 |
Teams of highly respected Alzheimer's researchers failed to replicate what appeared to be breakthrough results for the treatment of this brain disease when they were published last year in the journal Science.
7 hours ago | 5 / 5 (1) | 1 |
A brief visual task can predict IQ, according to a new study. This surprisingly simple exercise measures the brain's unconscious ability to filter out visual movement. The study shows that individuals whose ...
9 hours ago | 4.9 / 5 (7) | 0 |
Little is known about why asthma develops, how it constricts the airway or why response to treatments varies between patients. Now, a team of researchers at Weill Cornell Medical College, Columbia University Medical Center ...
7 hours ago | not rated yet | 0 |
Ethnic background plays a surprisingly large role in how diabetes develops on a cellular level, according to two new studies led by researchers at the Stanford University School of Medicine.
5 hours ago | not rated yet | 0 |