The NY Times provides perspective on the often overlooked enteric nervous system — the second brain, controlling our digestion and communicating with its more sophisticated sibling:
The enteric and central nervous systems use the same hardware, as it were, to run two very different programs. Serotonin, for instance, is crucial to feelings of well-being. Hence the success of the antidepressants known as S.S.R.I.’s that raise the level of serotonin available to the brain.
But 95 percent of the body’s serotonin is housed in the gut, where it acts as a neurotransmitter and a signaling mechanism…
Serotonin also acts as a go-between, keeping the brain in the skull up to date with what is happening in the brain below. Such communication is mostly one way, with 90 percent traveling from the gut to the head.
Many of those messages are unpleasant, and serotonin is involved in sending them. Chemotherapy drugs like doxorubicin, which is used to treat breast cancer, cause serotonin to be released in the gut, leading to nausea and vomiting. “The gut is not an organ from which you wish to receive frequent progress reports,” Dr. Gershon said.
Indeed, but we enjoy hearing about this perspective on gastrointestinal physiology. Many CNS disorders have GI components, and, as mentioned above, drugs affecting one system can have side effects on another. We’d do well to be mindful of this cross-talk, if we could figure out which mind we’re thinking with.
More from Dr. Michael Gershon’s article in Hospital Practice (7/99)…
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