Christine Latham, M.S.
Currently, rodents are the most commonly used model for human aging, but because they have much shorter lifespans and many physical dissimilarities from humans, they may not be the best possible model for humans. So, what should we use if the time-honored rodent model is not the best option? Interestingly enough, horses may be able to fill the gap between easy-to-use mouse models and hard-to-control human studies. But why horses? Horses are an athletic species, they have the longest lifespan of any domestic animal, and they have the potential to be an excellent model for human aging and exercise, as their health declines with age in a similar pattern to humans. We know that, like humans, aging in horses is accompanied by a loss of muscle mass and function, and research in humans and other species indicates this is likely due to impaired mitochondrial function and chronic inflammation. Unfortunately, while there is a great deal of research on how to turn an aged frown upside-down in humans and rodents, very little is known about how to support the health and well-being of our aging equine companions.
Fortunately, something as simple and inexpensive as regular exercise may be able to rescue us all from the maladies of aging. Regular low-intensity exercise is associated with multitudes of health benefits, like improvements in antioxidant capacity, decreasing circulating inflammatory cytokines, and maintenance of healthy muscle fiber energetics in other species. However, there has been limited research of these effects of exercise in horses, and virtually none has been performed in aged horses. Therefore, the specific objective of a new study is to test the hypothesis that exercise will reduce inflammation and improve mitochondrial number and function in aged horses. This study will utilize high resolution respirometry, a novel technique rarely used in equine muscle physiology research, allowing for more precise and accurate analysis of mitochondrial capacity than has previously been possible. The results of this study will offer insight into whether aged horses respond to exercise similarly to the way aged humans respond. If they do, future research done on healthy aging in horses could provide a tremendous amount of information about the aging process in humans, and how we can use exercise or other interventions to improve the quality of life of aging individuals of both species.