As always, the past few weeks were packed with interesting science articles, including a number of interesting findings involving mice. Laboratory mice (frequently variations on the common house mouse Mus Musculus) are frequently used in studies on genetics, psychology, physiology, and medicine. This is in large part due to their close homology to humans: on average, mouse and human genes are ~85% similar, with some genes being 99% identical. Therefore, research in mice can often represent a potential link to humans.
In an article published May 5th in the Journal Science, a group of researchers from Harvard University were able to show reversed aging symptoms in adult mice. Amazingly, the authors found that injecting aged mice with the protein Growth Differentiation Factor 11 (GDF11) was able to increase strength and endurance in the aged mice. These studies build on years of work on aging that have, quite literally, shown the benefits of “young blood”. Early studies found that a blood transfusion from young to old mice was able to increase muscle and brain function. Blood is a complicated mixture of cells and plasma, the protein and sugar rich fluid our blood cells are suspended in. Therefore, researchers were unsure which component was acting in the old mice to reverse the signs of aging.
To answer this question, researchers first examined the components of serum, including proteins and lipids, to find differences between old and young blood. This screen found that GDF11 was significantly decreased in old mice, and tests found that GDF11 alone could mimic whole blood. In fact, treating mice with GDF11 as able to reverse age-related heart disease! An additional study in Science this week found similar results from GDF11 injection, with an increase in brain function found in aged mice.
More research will be needed to determine the magnitude of these effects on aging, and if the results will be applicable to humans. Still, these studies reveal a potential therapy for age-related muscular and neurodegenerative diseases
In a more light-hearted study, published this week in Nature, a group from McGill University in Montreal found that the gender of researchers can influence a stress response in laboratory mice. Researchers examined the response from mice treated by male or female scientists and found that mice showed increased stress around men. In fact, the mice were so sensitive to the sex of the handler that they showed an elevated stress response when a T-shirt worn by a man was left in the animal room.
While this study is interesting in its own right, it might also represent an important (and overlooked) factor in research. If the gender of a researcher is enough to influence the behavior of mice it might influence the reproducibility of a study when attempted in another lab. Who can say what other factors are currently dismissed, but might actually have an important effect on research?