On Wed, 3 Sep 2003, Nathalie Cote went: > One of my Intro Psych students told me that he found a Web site that > says that the gastrointestinal tract is a bigger producer of serotonin > than the brain is
That's what I've been taught--that 90% of the body's serotonin is in the gut, where it serves functions related to intestinal motility. > The student is concerned because he has had his colon removed for > medical reasons, so he wants to know if that affects serotonin > levels in his brain. No, there's nothing to worry about there. Serotonin doesn't penetrate the blood-brain barrier, so the student's digestive tract can make as much (or as little) serotonin as it likes, and his brain won't know the difference, so to speak. Serotonin in the brain is made in specific clusters of neuron in the brainstem, whose axons form specific pathways with specific (perhaps even opposing) functions in various other brain regions. It's not something that the brain needs to be globally bathed in, like cerebrospinal fluid, and more isn't necessarily better. > 1) What do you know about serotonin in the gut? Other than being the > same chemical, is it related to serotonin in the brain? How? I think that when nature finds a useful signaling molecule, it uses that molecule wherever it can. So the same molecules tend to turn up in a lot of different places; that doesn't have to mean they're serving the same functions. > 2) The Web site above also makes the claim that "inadequate levels of > serotonin and norepinephrine precursors in the diet ...probably constitute a condition that almost never occurs. > is it the case that extended use of SSRIs depletes > neurotransmitters? No--at least, it's never been demonstrated. There are studies showing that huge overdoses of SSRIs can damage serotonergic axons in rats. Those studies have no implications for chronic use of therapeutic doses. > And is it the case that diet has a measurable effect on > neurotransmitter levels in the brain? Generally not, unless you go to unusual lengths, such as fasting, then drinking specially made cocktails of amino acids from which tryptophan is deliberately excluded. --David Epstein [EMAIL PROTECTED] --- You are currently subscribed to tips as: [EMAIL PROTECTED] To unsubscribe send a blank email to [EMAIL PROTECTED]
