Some people might say it's best to trust your gut, maybe because there is a 'second brain' there; the enteric nervous system is a network of cells that are woven into the walls of the gastrointestinal tract. It can control movements in the gut, and influence the activity of other cells. In many ways, the enteric nervous system can function independently of the central nervous system that controls most of our bodily functions. There are many specialized cell types found there as well. Neurons in the gut help coordinate its movement, such as contractions. But another type of cell called glia, which have been known as a support network for neurons, can also be found there. In recent years, research has shown that in the brain, glia can perform other functions beyond just helping neurons too. Scientists have been trying to learn more about the function of glia in the gut.
"It's like this second brain in our gut. It's an extensive network of neurons and glia that line our intestines," said Brian Gulbransen, a Michigan State University (MSU) Foundation Professor in the College of Natural Science's Department of Physiology.
Reporting in the Proceedings of the National Academy of Sciences, Gulbransen's team has determined that in the enteric nervous system, glia may be influencing the signals that move through neuronal circuits. Glia are playing an active role in signaling, suggested Gulbransen. But they don't appear to be initiating or receiving the signals like neurons do. Instead, they seem to modulate the electrical signals that travel through neural circuits, potentially dampening or amplifying the current as it moves.
Gulbransen's team has suggested that glia may help us understand how irritable bowel syndrome arises. Glial cells could also be influencing gastrointestinal disorders like constipation, or a rare problem called chronic intestinal pseudo-obstruction. In that disease, which has an unknown cause, a section of gut simply ceases to function, causing what seems like an obstruction, though there isn't a physical block.
Glial cells may be playing a far more important role in orchestrating the activity of the gut than we appreciated. Knowing more about the proper function of the gut will also help scientists and clinicians create treatments for disorders that disrupt the gut.
"This is a ways down the line, but now we can start to ask if there's a way to target a specific type or set of glia and change their function in some way," Gulbransen said. "Drug companies are already interested in this."