Neurogastroenterology: The Study of Our Second Brain
Posted Jan 01 2013 11:55pm
Early in embryogenesis our brains and our gut are formed from the same tissue mass with one half becoming the central nervous system and the other the enteric nervous system, connected by the vagus nerve. Half our nerves are located in our brain, and half in the gut which translates into a lot more than feeling butterflies in our stomach when we’re nervous.
This enteric nervous system is comprised of one hundred million autonomously functioning neurons, neurotransmitters and proteins with the ability to communicate with the central nervous system through the vagus nerve and parasympathetic nervous system. Coupled with the intestinal microbiome, it’s been coined our “second brain” by Dr. Michael Gershon, professor of anatomy and cell biology at Columbia-Presbyterian Medical Center in New York City in 1988. What we put into one brain drastically affects the other.
If we add the nerve cells of the esophagus, stomach and large intestine, there are more nerve cells in the gut than there are in the entire remainder of the peripheral nervous system. Nearly every chemical that controls the brain in the head has been identified in the gut, including hormones and neurotransmitters.
Flora, the microorganisms that typically inhabit a body organ, while plentiful, have not evolved enough to withstand processed and junk foods. Intestinal flora is also destroyed by considerable amounts of stress, alcohol, and antibiotics which will leave a body more open to infection.
Brain/Gut Disease States
Nearly 60 million people suffer from digestive issues. But other diseases also result from poor management of the second brain. Many are temporary ill feelings, while others are chronic and debilitating. The brain/gut connection has spurned interest in new research and procedures.
Gastrointestinal: The gut produces 95% of mood-stabilizing serotonin. So when it’s not functioning properly, our moods will show it. Conversely, when brain chemistry is off-balance, the bowels will suffer. Nearly 90% of people with irritable bowel syndrome (IBS) and non-ulcerative dyspepsia suffer from some sort of mental anxiety (or worse). These patients also frequently encounter abnormal REM sleep and wake feeling fatigued. These sleep disorders are often treated with low-dose antidepressants, regularly prescribed to treat IBS. This is also linked to depression, PTSD and bacterial infections.
Diabetes: Now epidemic in many countries, diabetes’ side effects can be devastating to the body, and treatment and utilization rates are drowning health care resources. The race is on to find new methods to slow glucose production to decrease related morbidity. Clinical trials show that fats activate a subset of nerves in the intestine, signaling the brain, which then signals the liver, to reduce glucose production. This helps to slow the production of sugar in the body. Now the gut, instead of the brain, will be the target for new therapies.
Anxiety and Depression: Antidepressant drugs commonly cause gastrointestinal problems such as nausea, diarrhea and constipation. This is because they inhibit the uptake of serotonin, which normally calms the digestive tract. Morphine and heroin which act on the central nervous system attach to the gut’s opiate receptors, producing constipation. The gut also produces benzodiazepines, chemicals that relieve pain and are found in anti-anxiety drugs like Valium. In extreme pain, the gut over-produces these chemicals and sends them to the brain. Stress signals are sent to the enteric nervous system, slowing digestion while the intestines contract.
GERD (Gastroesophageal Reflux Disease or heartburn): Prevalence of GERD has increased 50% in the past decade, affecting 20% of adults. Alcohol increases stomach acid and weakens the esophageal sphincter allowing caustic acid into your upper GI tract. Stress, a common cause of acid reflux and chronic heartburn, excites areas of the brain that make esophageal pain receptors more active. Additionally, these patients often have a drop in prostaglandins which coat the stomach lining and protect it from acid. Anti-inflammatory drugs reduce production of prostaglandins, which is why this class of drug often causes ulcers and nausea.
Settle Your Stomach
Try incorporating these items into your lifestyle for good gut/brain health:
Eliminate fatty foods and caffeine (try calming herbal teas, like chamomile)
What’s your gut feeling?
Lipman, Frank, MD, (2011) Revive: Stop Feeling Spent And Start Living Again.