If you’ve ever lived with your grandparents or other elderly people, you may have had arguments about setting the temperature too low. This is often because people feel more sensitive to cold as they age. Research this week appears to have uncovered the main reason why this is happening.
Scientists at City of Hope Medical Center in California studied brown fat cells in mice. They found evidence that these cells are less able to switch to their highly active state in older mice. They also managed to reverse this sluggishness with a drug, suggesting that it is possible to safely restore people’s heat-burning potential.
The findings provide a “fundamental understanding of the mechanisms underlying increased sensitivity to cold in older adults,” the researchers wrote in their paper published Wednesday in the journal Nature.
A less active oven
Humans and other mammals like mice carry three types of body fat: white, brown and beige. White fat cells are primarily for storing energy, while brown fat cells (also known as thermogenic fat cells) play a key role in keeping our body temperature stable; beige fat cells can do both.
There are several factors that explain why people may feel colder as they age, such as reduced blood flow to the extremities and a less responsive hypothalamus, the region of the brain that helps regulate bodily functions like sweating and shivering. But our body’s brown fat cells also seem to lose some of their oomph over time.
The team’s previous work has shown that there are different types of brown fat cells, some of which are much more efficient at generating heat. In this new study, researchers used mice as a model to study the system that regulates the availability of these different types.
They discovered that certain immune cells produce proteins that move highly active brown fat cells back to their dormant state. Levels of these proteins generally decreased when mice were exposed to cold and increased in heat, allowing the body to respond in real time to temperature changes.
In older mice, however, levels of these proteins tended to remain high, meaning the mice couldn’t generate heat from their brown fat cells as efficiently as before. The researchers then used the drug mifepristone, best known for helping induce abortion in women, to suppress the activation of a protein-triggered pathway, preventing some of this age-related slowing.
What could this mean
Further work will obviously be needed to confirm whether this system works the same way in humans as it does in mice. And researchers aren’t saying we can now easily reverse cold sensitivity in older people. Although mifepristone is safely used for abortion, it affects many different parts of the body, making it impractical as a treatment to rejuvenate brown fat cells, researchers say.
Assuming these results are valid, it is possible that we will find other drugs or interventions that can safely increase brown fat cell potency. And such treatments could have all kinds of uses beyond reducing our heating bills.
“Thermogenic fat also burns glucose and fat, and its activity tends to decrease with age. If scientists can find a safe and precise way to restore this activity, this basic research could potentially deepen our understanding of age-related metabolic problems, including obesity and type 2 diabetes,” said lead author Qiong “Annabel” Wang, an associate professor at the Arthur Riggs Diabetes and Metabolism Research Institute at City of Hope, in a news release from the institute.
In the meantime, perhaps it’s good to know that as I get older, I can simply blame my worry about buildings being too cold on my biological aging.
Gn tech
