RON STUBBS


			RON STUBBS *This article is the second in a series written by one of my Advanced Clinical Hypnotherapy students.* The Enteric Nervous System: The Brain/Gut Connection This article covers the Enteric Nervous System, which is described as the second brain. A general description of what makes the Enteric Nervous System brain like is described, as well as some of its role in Functional Bowel Disorders. The Enteric Nervous System Most people have experienced butterflies in the stomach, or a queasy feeling when facing a tense situation. Maybe it is more of sinking feeling in the pit of the stomach when feeling guilty or afraid. Maybe, it is a pleasant sensation, like that sense of anticipation when you are about to spend time with your new love. Everyone has different reactions to these stimuli, but everyone has experienced some kind of feeling in their guts, in reaction to a thought or situation. In the previous article, we briefly mentioned the Enteric Nervous System, this chapter goes into more detail of what it is, how it works, and some of the reasons it reacts the way it does. The Enteric Nervous System (ENS) is an immense system of Neurons; the system actually contains as many neurons as the entire spinal column. The Gastrointestinal tract is a long tube, which moves food from the esophagus to the ultimate elimination of waste products at the anus. The ENS exists within the walls of the GI Tract and actually consists of two separate networks, the Myentric plexus and the Submucous plexus. These neurons are responsible for function of the entire digestive system, and in fact most functioning of the digestive system can be done without intervention of the brain or spinal cord. According to German Scientist Paul Trendelenburg, no other organ in the body has this level of neurological development, and can operate in the absence of the brain. The Myentric plexus is primarily responsible for controlling this forward movement, while the Submucous plexus is primarily responsible for sensing the environment, and regulating blood flow and cell function. There are three different neurons in the ENS, the Sensory, Inter and Motor Neurons. The sensory neurons receive information for sensory receptors in the GI Tract. These receptors are sensitive to heat, motion, pressure and chemical contents. In other words, the sensory neurons are able to understand what the contents of the digestive tract are. The Motor Neurons control the motility, or movement of contents of the digestive tract. They also control secretion of chemicals, and possibly, the absorption of nutrients as well. The Interneurons provide the information from the Sensory Neurons, to the Motor neurons and visa-versa so they work together. In a typical example, the Sensory neurons would be able to detect that short chain fatty acids are present in the intestines. These neurons transmit information (neurotransmitters) through the interneurons, to the Motor neurons which then enhance motility (The speed of movement through the digestive tract). The presence of certain other nutrients can reduce this motility. This starts to explain why sufferers of functional bowel disorders such as IBS need to control the types of food they eat. These neurons, working together and transmitting a wide variety of neurotransmitters, such as serotonin, nitric oxide, vasoactive intestinal peptide and ATP closely resembles how the brain works. Low serotonin levels have been linked to depression, risky behavior and eating disorders. Interestingly, serotonin is produced in, and primarily used for the Enteric Nervous System. This similarity in function between the ENS and the brain, explains why certain anti-depressant drugs affect the gut, causing diarrhea, and eventually as the body becomes desensitized to serotonin, constipation. From this information, it is easy to see why neurotransmitter research is looking promising in the treatment of functional bowel disorders such as IBS. By the 1980’s there had been a considerable number of discoveries made regarding Neurons and Neurotransmitters. It was determined that there are over 30 classes of chemicals that transmit information in the brain, and all of these classes are represented in the ENS. Also, like the Central Nervous system, the neurons in the ENS are supported in glia, not collagen and Schwann cells like the rest of the nervous system. Another interesting relationship that the ENS system has to the brain, is the presence of chemicals linked to “Brain” diseases. The bowels of patients with Parkinson’s disease were found to have Lewy bodies, and in patients with Alzheimer’s, amyloid plaques and neurofibillary tangles have been found. In fact, it is possible that in the future, Alzheimer’s disease will be able to be diagnosed by testing patient’s bowels and looking for the presence of these plaques. All of this evidence demonstrates how brain like, the digestive system is, and begins to explain why people with functional bowel disorders often describe the symptoms of their guts as having a mind of their own. So, you may be wondering, if my Enteric Nervous System is so much like a brain, and can operate without a spinal cord and brain, why does my state of mind have so much control over what my gut is doing? In order for the GI tract to function correctly, it does need communication through the Central nervous system, and the brain. For example, if you see your favorite food, your gut may react by suddenly making you feel hungry. It is easy to see that this is an important survival mechanism. This communication between the brain and gut occurs through the Vagus nerve. This nerve is a direct connection, between the brain and gut, and has constant messages flowing in both directions. The messages traveling from the gut to the brain, out number the messages traveling in the other direction, 9 to 1, although in sufferers of IBS, it sometimes feel like the other way around. These messages are the guts survival mechanisms, for example letting the brain know through pain or a need to vomit, that poisons have been ingested, or there has been an infection. The relationship of the brain, and the ENS is so closely related, that it is sometimes difficult to determine which is causing the discomfort. Do I feel discomfort because of anxiety, or anxiety because of discomfort? For several years, and even today, there was a misconception that Peptic ulcers were caused by anxiety and stress. This hypothesis was determined because most sufferers of Ulcers described feelings of anxiety. In actuality, Peptic ulcers are caused by the Helicobacter pylori virus. It seems likely, that the feelings of anxiety were caused by the symptoms of the ulcer, and not the other way around. When the brain triggers the bodies fight or flight response, adrenaline is released, and the body experiences a heightened awareness of surroundings. There are several changes in the body, such as rapid respiration and increased muscle tension. Systems that are not deemed as necessary, such as the bowels, are relaxed and this explains why diarrhea may occur. This is an example of how the brain can send signals to the digestive system, and the digestive system will respond. It is one brain telling the other brain what is should do. What if, this reaction was triggered in a different way? Suppose for example, you are about to give a talk or a go on an airplane (if you are scared of flying). You are nervous about the situation, and because of this, you are now more aware of your surroundings. Your heart starts to beat faster, as adrenaline is released. Your second brain, the brain in your ENS, is now receiving this information through neurotransmitters. Now everything going on in your body is similar to the above example, your ENS now responds in the way it is conditioned to, the bowels relax and you are set up for diarrhea, constipation and/or abdominal pain. There is still a considerable amount of neuroscience research left to be done on the Enteric Nervous System. We still don’t know for example which neurons control the complex functioning of the GI tract in motility or secretion. This research is however progressing rapidly, and we have come a long way in our understanding of the functioning of our digestive system. Once these relationships are understood, fewer and fewer conditions will be grouped together under the heading of functional bowel disease. Each condition will be able to receive a different treatment, aimed at targeting just the affected areas. This chapter discussed how closely the Enteric Nervous System resembles the functioning of the brain. It talked about how the ENS system “Tastes” its contents and signals the GI tract on how to react to these contents. It also mentioned how neurotransmitters carry information to and from the brain about the environment the body is in. In future chapters, I will discuss foods, which trigger IBS symptoms, and making good dietary choices as well as controlling psychological triggers. *Disclaimer: This article is for informational purposes only. It is not to be used for medical care. If you have a specific concern, please contact your medical professional. References Austgen, L., Bowen, R. A., DVM, PhD, & Rouge, M.. Control of Digestive System Function. In Pathophysiology of the Digestive System: chap.. The Enteric Nervous System. Retrieved March 8, 2003, from http://www.vivo.colostate.edu/hbooks/pathphys/digestion/basics/gi_nervous.html Bertrand, P. P., & Bornstein, J. C. (1999, February 8). ATP and 5-HT activate mucosal terminals of intrinsic sensory neurons of the intestine. Retrieved March 9, 2003, from http://dirac.physiol.unimelb.edu.au/enl/doc/bertrand00-falk.pdf Bolen, B., Ph.D. (2000). Breaking the Bonds of Irritable Bowel Syndrome: Vol. . A psycological approach to regaining control of your life. 5674 Shattuck Avenue, Oakland, CA 94609: New Harbinger Publications, Inc. Gershon, M. D. (1999). The Enteric Nervous System: A Second Brain. Hospital Practice. Retrieved February 8, 2003, from http://www.hosppract.com/issues/1999/07/gershon.htm Society for Neuroscience.. Serotonin and Judgment. In Brain Briefings (chap.) Retrieved March 8, 2003, from http://web.sfn.org/content/Publications/BrainBriefings/serotonin.html Join Free! My e-zine newsletter will keep you up-to-date on upcoming events, and special product offerings. Click Here to Join now!