Approximately 80 percent of the human body's total serotonin is located in the enterochromaffin cells in the gut, where it is used to regulate intestinal movements. The remainder is synthesized in serotonergic neurons in the CNS where it has various functions. These include the regulation of mood, appetite, and sleep. Serotonin also has some cognitive functions, including in 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 disgorge serotonin, where it serves as a vasoconstrictor and helps to regulate hemostasis and blood clotting. Serotonin also is a growth factor for some types of cells, which may give it a role in wound healing.
Serotonin is mainly metabolized to 5-HIAA, chiefly by the liver. Metabolism involves first oxidation by monoamine oxidase ( MAO ) 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 kidneys. One type of tumor, called carcinoid, sometimes secretes large amounts of serotonin into the blood, which causes various forms of the carcinoid syndrome of flushing, diarrhea, and heart problems. Because of serotonin's growth promoting effect on cardiac myocytes, persons with serotonin-secreting carcinoid may suffer a right heart (tricuspid) valve disease syndrome, caused by proliferation of myocytes onto the valve.
In addition to animals, serotonin is also found in fungi and plants. 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 amoebas, 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.
If irritants are present in the food, the enterochromaffin cells release more serotonin to make the gut move faster, i.e., to cause diarrhea, so that the gut is emptied of the noxious substance. If serotonin is released in the blood faster than the platelets can absorb it, the level of free serotonin in the blood is increased. This activates 5HT3 receptors in the chemoreceptor trigger zone that stimulate vomiting. The enterochromaffin cells not only react to bad food, they are also very sensitive to irradiation and cancer chemotherapy. Drugs that block 5HT3 are very effective in controlling the nausea and vomiting produced by cancer treatment, and are considered the gold standard for this purpose.
In March 2011, Chinese scientists found male mice lose their heterosexuality if bred without serotonin. By taking away the tryptophan hydroxylase 2 gene, which is needed to produce serotonin, male mice were deprived of it. They also injected mice with a chemical that depletes serotonin. In that case, the male mice showed a preference for other male mice. When injected with a compound to restore serotonin, they returned to female mating preferences. However, experts have warned against making links between serotonin and human sexuality, as sexual preference in mice is largely driven by odours; humans are far less affected by odour cues.
Some serotonergic agonist drugs also cause fibrosis anywhere in the body, particularly the syndrome of retroperitoneal fibrosis, as well as cardiac valve fibrosis. In the past, three groups of serotonergic drugs have been epidemiologically linked with these syndromes. They are the serotonergic vasoconstrictive antimigraine drugs (ergotamine and methysergide), the serotonergic appetite suppressant drugs (fenfluramine, chlorphentermine, and aminorex), and certain anti-Parkinsonian dopaminergic agonists, which also stimulate serotonergic 5-HT2B receptors. These include pergolide and cabergoline, but not the more dopamine-specific lisuride. As with fenfluramine, some of these drugs have been withdrawn from the market after groups taking them showed a statistical increase of one or more of the side effects described. An example is pergolide. The drug was declining in use since reported in 2003 to be associated with cardiac fibrosis. Two independent studies published in the New England Journal of Medicine in January 2007, implicated pergolide, along with cabergoline, in causing valvular heart disease. As a result of this, the FDA removed pergolide from the U.S. market in March, 2007. (Since cabergoline is not approved in the U.S. for Parkinson's Disease, but for hyperprolactinemia, the drug remains on the market. Treatment for hyperprolactinemia requires lower doses than that for Parkinson's Disease, diminishing the risk of valvular heart disease).
Serotonin in mammals is made by two different tryptophan hydroxylases: TPH1 produces serotonin in the pineal gland and the enterochromaffin cells, while TPH2 produces it in the raphe nuclei and in the myenteric plexus. Genetically altered mice lacking TPH1 develop progressive loss of heart strength early on. They have pale skin and breathing difficulties, are easily tired, and eventually die of heart failure. Genetically altered mice that lack TPH2 are normal when they are born. However, after three days they appear to be smaller and weaker, and have softer skin than their siblings. In a purebred strain, 50% of the mutants died during the first four weeks, but in a mixed strain, 90% survived. Normally, the mother weans the litter after three weeks, but the mutant animals needed five weeks. After that, they caught up in growth and had normal mortality rates. Subtle changes in the autonomic nervous system are present, but the most obvious difference from normal mice is the increased aggressiveness and impairment in maternal care of young. Despite the blood-brain barrier, the loss of serotonin production in the brain is partially compensated by intestinal serotonin. The behavioural changes become greatly enhanced if one crosses TPH1- with TPH2-lacking mice and gets animals that lack TPH entirely.
In humans, defective signaling of serotonin in the brain may be the root cause of sudden infant death syndrome (SIDS). Scientists from the European Molecular Biology Laboratory in Monterotondo, Italy genetically modified lab mice to produce low levels of the neurotransmitter serotonin. The results showed the mice suffered drops in heart rate and other symptoms of SIDS, and many of the animals died at an early age. Researchers now believe low levels of serotonin in the animals' brainstems, which control heartbeat and breathing, may have caused sudden death, they said in the July 4, 2008 issue of Science. If neurons that make serotonin — serotonergic neurons — are abnormal in infants, there is a risk of sudden infant death syndrome (SIDS).
Low levels of serotonin may also be associated with intense spiritual experiences.
Recent research conducted at Rockefeller University shows, in both patients who suffer from depression and mice that model the disorder, levels of the p11 protein are decreased. This protein is related to serotonin transmission within the brain.
Serotonin taken orally does not pass into the serotonergic pathways of the central nervous system, because it does not cross the blood-brain barrier. However, tryptophan and its metabolite 5-hydroxytryptophan (5-HTP), from which serotonin is synthesized, can and does cross the blood-brain barrier. These agents are available as dietary supplements, and may be effective serotonergic agents. One product of serotonin breakdown is 5-hydroxyindoleacetic acid (5 HIAA), which is excreted in the urine. Serotonin and 5 HIAA are sometimes produced in excess amounts by certain tumors or cancers, and levels of these substances may be measured in the urine to test for these tumors.
Although phobias and depression might be attenuated by serotonin-altering drugs, this does not mean the individual's situation has been improved, but only the individual's perception of the environment. Sometimes, a lower serotonin level might be beneficial, for example in the ultimatum game, where players with normal serotonin levels are more prone to accept unfair offers than participants whose serotonin levels have been artificially lowered.
However, since serotonin is a major gastrointestinal tract modulator, it may be produced by plants in fruits as a way of speeding the passage of seeds through the digestive tract, in the same way as many well known-seed and fruit associated laxatives. Serotonin is found in mushrooms, fruits and vegetables. The highest values of 25–400 mg/kg have been found in nuts of the walnut (Juglans) and hickory (Carya) genera. Serotonin concentrations of 3–30 mg/kg have been found in plantain, pineapple, banana, kiwifruit, plums, and tomatoes. Moderate levels from 0.1–3 mg/kg have been found in a wide range of tested vegetables.
Serotonin is one compound of the poison contained in stinging nettles (Urtica dioica), where it causes pain on injection in the same manner as its presence in insect venoms (see above).
Unlike its precursors, 5-HTP and tryptophan, serotonin does not cross the blood–brain barrier, which means that ingesting serotonin in the diet has no effect on brain serotonin levels.
Category:Serotonin Category:Natural tryptamine alkaloids Category:Biogenic amines
ar:سيروتونين bg:Серотонин ca:Serotonina cs:Serotonin da:Serotonin de:Serotonin et:Serotoniin el:Σεροτονίνη es:Serotonina eo:Serotonino eu:Serotonina fa:سروتونین fr:Sérotonine ko:세로토닌 hy:Սերոտոնին hr:Serotonin id:Serotonin it:Serotonina he:סרוטונין kk:Серотонин la:Serotoninum lt:Serotoninas hu:Szerotonin nl:Serotonine ja:セロトニン no:Serotonin oc:Serotonina pl:Serotonina pt:Serotonina ro:Serotonină ru:Серотонин simple:Serotonin sl:Serotonin sr:Серотонин sh:Serotonin fi:Serotoniini sv:Serotonin th:เซโรโทนิน tr:Serotonin uk:Серотонін ur:Serotonin zh:血清張力素This text is licensed under the Creative Commons CC-BY-SA License. This text was originally published on Wikipedia and was developed by the Wikipedia community.
Coordinates | 28°36′36″N77°13′48″N |
---|---|
name | Simple Kid |
background | solo_singer |
birth name | Kieran McFeely |
origin | Cork, Ireland |
instrument | Vocals, guitar, banjo, harmonica |
genre | AlternativeElectronicaFolkIndustrial rock |
occupation | Singer-songwriter, musician |
label | 2m, Vector Recordings, Gentlemen Recordings, Yep Roc Records |
associated acts | The Young Offenders |
website | SimpleKid.com |
notable instruments | }} |
Simple Kid, real-name Ciaran McFeely, is an Irish-born solo musical artist.
Simple Kid's influences include folk, country (he prominently features banjos and slide guitar in his work), glam rock (particularly T. Rex) and late 60s big pop arrangements of records like The Beatles's 'White Album'.
Before becoming Simple Kid, McFeely was a member of The Young Offenders. Forming when he was 17, the band was composed of friends made while growing up in Cork Ireland. The group attempted to release an album in America but met with failure and broke up.
Although having spent considerable time in America before becoming Simple Kid, his popularity today is mostly limited to the United Kingdom and Ireland. His touring is based out of London and he has played support for R.E.M. and Kings Of Leon,Snow patrol at ward park. among others.
Television appearances include Later... with Jools Holland, Late Night with Conan O'Brien, The Late Late Show and Other Voices on RTE. He's also been the subject of a Channel 4 (4 Play) short documentary and appeared on TFI Friday with The Young Offenders.
His second album, 2, was released by Country Gentleman Recordings in October 2006 in the UK, and by Yep Roc Records in August 2007 in the US. "2" was included in Mojo Magazine's top 50 albums of the year, was CD of the week in The Times Culture section and had positive reviews in the NME, The Guardian, Time Out and the Independent on Sunday, to name a few. The Rolling Stone Magazine also featured Simple Kid as a breakthrough act for 2007.
The track "Lil' King Kong" off "2" is featured in a Saturn automobile advertisement in the US, as well as in an advertisement in the UK for the mobile phone operator Orange. "Lil' King Kong also featured in Hollywood movie Jumper in 2008.
In early 2011 it was announced on the official website that there will be no further music or tours by Simple Kid.
Category:Irish country musicians Category:Music from Cork Category:Living people Category:Year of birth missing (living people)
de:Simple Kid pl:Simple KidThis text is licensed under the Creative Commons CC-BY-SA License. This text was originally published on Wikipedia and was developed by the Wikipedia community.
Paul Collier, CBE is a Professor of Economics, Director for the Centre for the Study of African Economies at The University of Oxford and Fellow of St Antony's College. From 1998 – 2003 he was the director of the Development Research Group of the World Bank.
The Bottom Billion: Why the Poorest Countries are Failing and What Can Be Done About It (ISBN 0195311450), has been compared to Jeffrey Sachs's The End of Poverty and William Easterly's The White Man's Burden, two influential books, which like Collier's book, discuss the pros and cons of developmental aid to developing countries.
His 2010 book The Plundered Planet is encapsulated in his formulas: Nature - Technology + Regulation = Starvation, Nature + Technology - Regulation = Plunder, and Nature + Technology + Regulation (Good governance) = Prosperity. The book describes itself as an attempt at a middle way between the extremism of "Ostriches" (Denialism, particularly climate change denial) and "Environmental Romanticism" (for example, anti-genetically modified organisms movements in Europe). The book is about sustainable management in relation with the geo-politics of global warming, with an attempt to avoid a global tragedy of the commons, with prime example of overfishing. In it he builds upon a legacy of the economic psychology of greed and fear, from early Utilitarianism (Jeremy Bentham) to more recently the Stern Review.
He was appointed Commander of the Order of the British Empire (CBE) in the 2008 Birthday Honours. He is a patron of the Media Legal Defence Initiative.
In 2010, he was named by Foreign Policy magazine to its list of top global thinkers.
He is currently working for the Copenhagen Consensus, where he is the expert on conflict.
Category:British economists Category:Year of birth missing (living people) Category:Living people Category:Sustainability advocates Category:Development specialists Category:Climate economists Category:Commanders of the Order of the British Empire Category:Fellows of St Antony's College, Oxford Category:People educated at King Edward VII School, Sheffield
de:Paul Collier nl:Paul Collier ja:ポール・コリアー no:Paul Collier sk:Paul Collier ta:போல் கொலியர்This text is licensed under the Creative Commons CC-BY-SA License. This text was originally published on Wikipedia and was developed by the Wikipedia community.
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