Running and Serotonin: What Happens in Older Mice?

Did you know that as mice age, they have fewer serotonin-producing neurons? These neurons are crucial for brain function and learning. Scientists found that older mice have fewer of these neurons in two key brain areas: the dorsal raphe nucleus (DRN) and the median raphe nucleus (MRN). This was especially true for older female mice. But what does this mean? Serotonin plays a big role in how our brains respond to physical activity. It helps new brain cells grow in a region called the dentate gyrus (DG). When older mice ran on a treadmill, their brains didn't respond as much as younger mice. Specifically, a protein called c-Fos, which shows brain cell activity, was less active in the DG of older mice after running. So, why is this important? It suggests that as we age, our brains might not respond as well to physical activity due to lower serotonin levels. This could impact our ability to learn and stay sharp. But don't worry, there's still a lot to learn about how aging affects our brains and what we can do to stay mentally fit!