More than 100 million neurons are present in the intestine. Some of them report the pain. But the latter would not only be responsible for stomach aches. According to a new study by researchers at Harvard Medical School, they would also help protect the intestines from inflammation and damage.
Pain neurons would protect the microbiota
For this work, the scientists studied the functioning of the goblet cells of mouse. They contain gel-like mucus made up of proteins and sugars. When the latter responds to the surface of the organs, it protects them from harm.
The Harvard team discovered that pain neurons in the gut regulate the presence of this protective mucus and encourage these intestinal cells to release it during the inflammatory episodes.
“It appears that pain can protect us in more direct ways than its classic job of detecting potential damage and sending signals to the brain. Our work shows how pain mediating nerves in the intestine communicate with nearby epithelial cells that line the intestines,” said study lead researcher Isaac Chiu, an associate professor of immunobiology at the Blavatnik Institute of Havard Medical School.” This means that the nervous system plays a major role in the gut beyond just giving us an unpleasant feeling. It is a key player in maintaining the intestinal barrier and a protective mechanism during inflammation.”
Additionally, the researchers noticed that rodents lacking pain neurons produced less protective mucus. There were also changes in the intestinal microbial composition animals studied, imbalance between beneficial and harmful microbesknown as dysbiosis.
Pain neuron: food also plays a role
Diet may also play a role in activation of pain receptors. In a second experiment, some mice were fed capsaicinthe main ingredient of red peppers also known for its ability to cause suffering. The researchers indicate that pain neurons were quickly activatedcausing the release of copious amounts of mucus protection by goblet cells.
In contrast, mice lacking pain neurons or goblet cell receptors were more sensitive to the colitis, a form of intestinal inflammation. “This finding could explain why people with gut dysbiosis may be more prone to colitis,” the scientists explain in their article published October 14 in the scientific journal Cell.
“Pain is a common symptom of chronic inflammatory bowel conditions, such as colitis, but our study shows that acute pain also plays a direct protective role“, concluded the first author, Daping Yang, postdoctoral researcher at Harvard’s Chiu Lab.
Faced with their results, the researchers wonder about the possible harmful consequences of taking painkillers in people with intestinal inflammation. “Part of the pain signal could be directly protective as a neural reflex, raising important questions about how to manage suffering so that it doesn’t lead to further harm.”