Enteric Nervous System - Understanding How The 'Second Brain' Works

Researchers from the Hotchkiss Brain Institute (HBI) in the Faculty of Medicine at University of Calgary have uncovered the first evidence that neurons talk to ‘glial’ cells in the digestive tract: a discovery that could help find a way to regulate and restore balance in the gut for the one in 10 Canadians suffering from irritable bowel syndrome (IBS) and the more than 200,000 Canadians suffering from inflammatory bowel disease (IBD).



Sometimes referred to as the “second brain”, the enteric nervous system controls function of the digestive tract. Similar to neurons found in the brain, neurons in the enteric nervous system, are surrounded by cells that insulate and protect nerves. The cells, known as “glial cells,” were typically thought not to influence gut function. While interactions between nerves and glia are becoming increasingly researched and well characterized in the brain, no one has been able to definitively show that enteric neurons can communicate with glial cells in the digestive tract—until now.



“This is an exciting discovery, because if we can understand how these cells respond to signaling mechanisms, and how their reactions change between a healthy digestive tract and in diseases such as IBD and IBS, it may lead to new or better treatment of gastrointestinal disorders,” said Keith Sharkey, PhD. “Neuron-glial signaling will also help us understand how the brain influences the gut and vice versa.”



In a study published this month in the journal Gastroenterology, HBI researchers were able to demonstrate that while neurons are “talking” to each other, glial cells are “listening in” on the conversation and responding to the molecules that the neurons are releasing.



“We knew that peripheral glial cells had the potential to receive signals, but this is the first evidence that glia may play a larger role in gut function than previously thought,” explained Brian Gulbransen, PhD, a postdoctoral fellow working in the laboratory with Sharkey.



“Thankfully, we’re in a wonderful collaborative research environment here at the HBI that allows us to fully explore those links,” said Sharkey.



Last year in collaboration with fellow HBI researchers, Sharkey showed that beyond the immediate damage caused by IBD, chronic inflammation in the digestive tract also increases neuronal excitability in the hippocampus, highlighting the critical link between the digestive tract and the brain.



Keith Sharkey is Professor of Physiology&Pharmacology in the Faculty of Medicine, the Crohn’s and Colitis Foundation of Canada Chair in IBD Research and an Alberta Heritage Foundation for Medical Research Scientist. He is a member of the HBI and the Calvin, Phoebe and Joan Snyder Institute of Infection, Immunity and inflammation.