- In hibernating animals, the stress of a declining food supply causes increased serotonin production. In humans and animals that don’t hibernate, the stress of winter causes very similar changes. Serotonin lowers temperature by decreasing the metabolic rate. Tryptophan and melatonin are also hypothermic. In the winter, more thyroid is needed to maintain a normal rate of metabolism.
- Overdose with the serotonin reuptake inhibitors, or with 5-hydroxytryptophan [or 5-HTP], which has effects similar to serotonin, can cause the sometimes fatal “serotonin syndrome.” Symptoms can include tremors, altered consciousness, poor coordination, cardiovascular disturbances, and seizures. Treatment with anti-serotonin drugs can alleviate the symptoms and usually can prevent death. [Note to self: super glad I stopped taking 5-HTP.]
- The serotonin syndrome has been reported in users of St. John’s wort as an antidepressant.
- Although several amino acids can be acutely or chronically toxic, even lethal, when too much is eaten, tryptophan is the only amino acid that is also carcinogenic. (It can also produce a variety of toxic metabolites, and it is very susceptible to damage by radiation.) Since tryptophan is the precursor of serotonin, the amount of tryptophan in the diet can have important effects on the way the organism responds to stress, and the way it develops, adapts, and ages.
- Decreasing tryptophan or decreasing serotonin improves learning and alertness, while increased serotonin impairs learning.
- Serotonin’s contribution to high blood pressure is well established. It activates the adrenal cortex both directly and through activation of the pituitary. It stimulates the production of both cortisol and aldosterone.
- If serotonin deficiency doesn’t cause depression, then what does?
- How do we treat mood disorders outside of increasing serotonin?
- Why do tryptophan, 5-HTP and St. John’s Wort make some people feel terrible (like me), but make others feel better?
- How did our ideas about serotonin get turned so upside down?
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