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Serotonin – Mens Sana in Corpore Sano

Source: http://worldhappiness.report/ed/2017/

 

Serotonin or 5-hydroxytryptamine (5-HT) is a monoamine neurotransmitter. Biochemically derived from tryptophan, serotonin is primarily found in the gastrointestinal tract (GI tract), blood platelets, and the central nervous system (CNS) of animals, including humans. It is popularly thought to be a contributor to feelings of well-being and 1) ___Approximately 90% of the human body’s total serotonin is located in the enterochromaffin cells in the GI tract, where it is used to regulate intestinal movements. The serotonin is secreted luminally and basolaterally which leads to increased serotonin uptake by circulating platelets and activation after stimulation, which gives increased stimulation of myenteric neurons and gastrointestinal motility. The remainder is synthesized in serotonergic 2) ___of the CNS, where it has various functions. These include the regulation of mood, appetite, and sleep. Serotonin also has some cognitive functions, including memory and learning. Modulation of serotonin at synapses is thought to be a major action of several classes of pharmacological antidepressants. Serotonin secreted from the enterochromaffin cells eventually finds its way out of tissues into the blood. There, it is actively taken up by blood platelets, which store it. When the platelets bind to a clot, they release serotonin, where it serves as a vasoconstrictor and helps to regulate hemostasis and blood 3) ___. Serotonin is also a growth factor for some types of cells, which may give it a role in wound healing. There are various serotonin receptors.

 

Serotonin is metabolized mainly to 5-HIAA, chiefly by the liver. Metabolism involves first oxidation by monoamine oxidase to the corresponding aldehyde. This is followed by oxidation by aldehyde dehydrogenase to 5-HIAA, the indole acetic acid derivative. The latter is then excreted by the 4) ___. In addition to animals, serotonin is found in fungi and 5) ___. Serotonin’s presence in insect venoms and plant spines serves to cause pain, which is a side-effect of serotonin injection. Serotonin is produced by pathogenic amoebae, and its effect on the gut, causes diarrhea. Its widespread presence in many seeds and fruits may serve to stimulate the digestive tract into expelling the seeds.

 

Serotonin syndrome (SS) is a group of symptoms that may occur following use of certain serotonergic medications or 6) ___. The degree of symptoms can range from mild to severe. Symptoms include high body temperature, agitation, increased reflexes, tremor, sweating, dilated pupils, and diarrhea. Body temperature can increase to greater than 41.1 oC (106.0 oF). Complications may include seizures and extensive muscle breakdown. Serotonin syndrome is typically caused by the use of two or more serotonergic medications or drugs. This may include selective serotonin reuptake inhibitor (SSRI), serotonin norepinephrine reuptake inhibitor (SNRI), monoamine oxidase inhibitor (MAOI), tricyclic antidepressants (TCAs), amphetamines, pethidine (meperidine), tramadol, dextromethorphan, buspirone, L-tryptophan, St. John’s wort, triptans, ecstasy, metoclopramide, ondansetron, or cocaine. It occurs in about 15% of SSRI overdoses. It is a predictable consequence of excess serotonin on the CNS or 7) ___ ___ ___. Onset of symptoms is typically within a day of the extra serotonin. Diagnosis is based on a person’s symptoms and history of medication use. Other conditions that can produce similar symptoms such as neuroleptic malignant syndrome, malignant hyperthermia, anticholinergic toxicity, heat stroke, and meningitis should be ruled out. No laboratory tests can confirm the diagnosis. Initial treatment consists of discontinuing medications which may be contributing. In those who are agitated benzodiazepines may be used. If this is not sufficient, a serotonin antagonist such as cyproheptadine may be used. In those with a high body temperatures active cooling measures may be needed. The number of cases of serotonin syndrome that occur each year is unclear. With appropriate treatment the risk of 8) ___ is less than one percent. The high-profile case of Libby Zion, who is thought to have died from serotonin syndrome, resulted in changes to graduate medical education in New York State and hospital procedures. The symptoms of serotonin syndrome are often described as a clinical triad of abnormalities.

 

Non-pharmacologic ways to raise serotonin levels in humans are: light therapy, meditation, psychotherapy, exercise and diet. Another important factor that could play a role in raising 9) ___ levels, is diet. According to some evidence, tryptophan, which increases brain serotonin in humans is an effective antidepressant in mild-to-moderate depression. Further, in healthy people with high trait irritability, it increases agreeableness, decreases quarrelsomeness and improves mood. Although purified tryptophan increases brain serotonin, foods containing tryptophan do not. This is because tryptophan is transported into the brain by a transport system that is active toward all the large neutral amino acids, and tryptophan is the least abundant amino acid in protein. After the ingestion of a meal containing protein, the rise in the plasma level of the other large neutral amino acids will prevent the rise in plasma tryptophan from increasing brain tryptophan. The idea, common in popular culture, that a high-protein food such as turkey will raise brain tryptophan and serotonin is, unfortunately, false. Another popular myth that is widespread on the Internet is that bananas improve mood because of their serotonin content. Although it is true that bananas contain serotonin, it does not cross the blood-brain barrier. Researchers have studied the tryptophan content of both wild chickpeas and the domesticated chickpeas that were bred from them in the Near East in Neolithic times. In the cultivated group, the tryptophan content was almost twice that of the wild seeds. Interestingly, the greater part of the increase was due to an increase in the free tryptophan content (i.e., not part of the protein). In cultivated 10) ___, almost two-thirds of the tryptophan was in the free form. Editor’s note: In our reading for this article so far, domesticated chickpeas appear to be the best dietary source contributing to healthy human serotonin levels. There may be other foods, but we have not come across them yet.

 

In an article in Nature Biotechnology, Morris and Sands argue that plant breeders should be focusing more on nutrition than on yield. They ask, “Could consumption of tryptophan-rich foods play a role in reducing the prevalence of depression and aggression in society?“ The constitution of the WHO states “Health is a state of complete physical, mental and social well-being and not merely the absence of disease or infirmity.“ This may sound like simple common sense, but it’s worth stating that positive mood within the normal range is an important predictor of health and longevity. Research confirms what might be intuitively expected, that positive emotions and agreeableness foster congenial relationships with others. This in turn will create the conditions for an increase in social support. Several studies found an association between measures related to serotonin and mood in the normal range. Lower platelet serotonin receptor function was associated with lower mood in one study, whereas better mood was associated with higher blood serotonin levels in another. Low serotonin may predispose healthy individuals to suboptimal physical as well as mental functioning. There is a strong possibility that the interaction between serotonin synthesis and mood may be 2-way, with serotonin influencing mood and mood influencing serotonin.

 

The first World Happiness Report was published in April 2012, in support of the UN High Level Meeting on happiness and well-being. Since then the world has come a long way. Increasingly, happiness is the proper measure of social progress and the goal of public policy. In June 2016 the OECD committed itself “to redefine the growth narrative to put people’s well-being at the center of governments’ efforts.“ In February 2017, the United Arab Emirates held a full-day World Happiness meeting, as part of the World Government Summit. Clearly, health, happiness and non-pharmacologic serotonin levels, are closely related. Sources: www.ncbi.nlm.nih.gov; WebMD.com; Wikipedia

 

World Happiness Report video

 

ANSWERS: 1) happiness; 2) neurons; 3) clotting; 4) kidneys; 5) plants; 6) drugs; 7) Central Nervous System; 8) death; 9) serotonin; 10) chickpeas

 

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