Our gut feeling rarely lets us down, although we know very little about how it happens. As science discovers more about the connection between the gut and brain, the role of the little-known and rare enterochromaffin (EC) cells becomes central to our understanding of how the brain and gut communicate. We have all felt butterflies or that wrenching feeling in our stomach when we are anxious, and we also know that long term anxiety and depression often leads to various disorders of the gastrointestinal (GI) tract. We have known for some time about that our mental state can affect the gut, and what we are discovering now with the help of modern research is how gut health affects the brain and general well-being. These days, it seems that what has been missing from this cyclic relationship is our understanding of EC cell functions.
Basic features of the gut-brain axis
To fully appreciate the role of EC cells, we have to delve into some basic underlying concepts and facts. Our gut has more neurons than our spine or peripheral nervous system—that is why it is also known as the second brain. These neurons have various functions, like controlling gut motility, protecting against irritants (through increased motility or vomiting), and many other still to be understood functionalities. These gut neurons mostly work independently from the brain, but when required, they send information and get feedback from the brain, thus functioning as a closed loop often called the gut-brain axis.
EC cells play a vital part in the gut-brain axis. These cells have receptors that are always listening to various activities in the gut and sending feedback to the brain and other neurons of the gut through chemical messengers or hormones. Although EC cells have functional similarities to glands, they are spread all over the digestive tract, and they form about one percent of the gut epithelium. Although one percent may sound small, EC cells secrete more than 30 kinds of hormones and neurotransmitters (this number will likely increase as more are identified). In fact, they secrete more than 90% of the body’s serotonin, a neurotransmitter well-known for its role in various mental states, including mental disorders like depression and anxiety.
Now, it is well understood that the communication between the brain and gut is double-sided, forming a loop. Thus, mental distress causes gut disorders, and gut disorders may influence mental states. Moreover, EC cells have a critical role in this entire axis.
Brain and GI disorders
Stress is known not only to cause GI disorders, but it also makes the symptoms worse. Stress and psychological factors change the movement of the GI tract, worsen inflammatory processes, and even increase susceptibility to various infections. In all of these processes, EC cells play a crucial role. The release of serotonin from EC cells is the key mechanism for controlling the motility of the gut. They can be stimulated due to local irritation, as well as through nerve supply, especially the