| Seratonin |
Articles about Serotonin |
Information AboutSeratonin |
| CATEGORIES ABOUT SEROTONIN | |
| biogenic amines | |
| neurotransmitters | |
| tryptamines | |
| natural tryptamine alkaloids | |
Serotonin ('''5-hydroxytryptamine''', or '''5-HT''') is a Monoamine Neurotransmitter synthesised in serotonergic Neuron s in the Central Nervous System and Enterochromaffin Cell s in the Gastrointestinal Tract . In the central nervous system, serotonin is believed to play an important role in the regulation of Mood , Sleep , Emesis (vomiting), Sexuality and Appetite . Serotonin has been thought to play a part in many disorders, notably as part of the Biochemistry of Depression , Migraine , Bipolar Disorder and Anxiety . The name "serotonin" is something of a misnomer and reflects the circumstances of the compound's discovery. It was initially identified as a vasoconstrictor substance in blood serum - hence ''serotonin'', a serum agent affecting vascular tone. This agent was later chemically identified as 5-hydroxytryptamine (5-HT), and, as the broad range of physiological roles were elucidated, 5-HT became the preferred name in the pharmacological field. BIOCHEMISTRY Serotonin is found extensively in the human Gastrointestinal Tract , or gut, as well as in the blood stream. In the body, serotonin is synthesized from the Amino Acid Tryptophan by short Metabolic Pathway consisting of two Enzyme s - TPH( 1 , 2 ) and DDC . TPH1 Reaction controls the flux through the pathway. 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, the Amino Acid Tryptophan and its metabolite 5-hydroxytryptophan , from which serotonin is synthesized, can and does cross the blood-brain barrier. These agents are available as Dietary Supplement s and may be effective serotonergic agents. One breakdown product of serotonin is 5-hydroxyindoleacetic acid ( 5 HIAA ) which is excreted in the Urine . Serotonin and 5HIAA are sometimes produced in excess amounts by certain Cancer Tumors , and levels of these substances may be measured in the urine to test for these tumors. NEUROTRANSMISSION Serotonergic action is terminated primarily via Uptake of 5-HT from the synapse. This is through the specific Monoamine Transporter for 5-HT, 5-HT Reuptake Transporter , on the presynaptic neuron. Various agents can inhibit 5-HT reuptake including MDMA , Cocaine , Tricyclic Antidepressants (TCAs) and Selective Serotonin Reuptake Inhibitor s (SSRIs). PHARMACOLOGY The Pharmacology of 5-HT is extremely complex, with its actions being mediated by a large and diverse range of 5-HT Receptors . As with all neurotransmitters, the actual effects of 5-HT on the human Mood and state of Mind , and its role in Consciousness , are very difficult to ascertain. One way of understanding it is through the use of MDMA , which is thought to cause a mass release of 5-HT, possibly by drawing it back through the transporter. The effects of . (MDMA also releases Norepinephrine , and to a much lesser extent, Dopamine . MDEA , a closely related drug, appears to be purely a serotonin releasing agent, and lacks the strong stimulant effect of MDMA.) 5-HT receptors are also used by other psychoactive drugs, including LSD , DMT , and Psilocybin , the active ingredient in Psychedelic Mushrooms . MODULATING LEVELS OF 5-HT A variety of Psychiatric Medication s affect serotonin levels, including the Monoamine Oxidase Inhibitors (MAOIs), Tricyclic Antidepressants (TCAs), Atypical Antipsychotic s, and the Selective Serotonin Reuptake Inhibitor s (SSRIs). Antidepressants The MAOI s prevent the breakdown of monoamine neurotransmitters (including serotonin), and therefore increase concentrations of the neurotransmitter in the brain. MAOI therapy is associated with many adverse drug reactions, and patients are at risk of hypertensive crisis triggered by foods with high Tyramine -content and certain drugs. Some drugs inhibit this re-uptake of serotonin, again making it stay in the synapse longer. The Tricyclic Antidepressants inhibit the re-uptake of both serotonin and Norepinephrine . The newer Selective Serotonin Re-uptake Inhibitors (SSRIs) have fewer (though still numerous) side effects and fewer interactions with other drugs. Antiemetics 5-HT3 Antagonist s such as Ondansetron , Granisetron and Tropisetron are important antiemetic agents. They are particularly important in treating the Nausea and Vomiting that occur during anticancer chemotherapy using cytotoxic drugs. Another application is in treatment of post-operative nausea and vomiting. Applications to the treatment of depression and other mental and psychological conditions have also been investigated with some positive results. Deficiency Deficient (and sometimes, excessive) intake of various Dietary Minerals , Drugs , and Vitamin s can lead to disturbed levels of serotonin via disrupting either the production or reuptake processes. Serotonin syndrome Care must be taken in any attempt to increase serotonin levels, as a dangerous condition known as Serotonin Syndrome may result. This is especially a concern if multiple serotonergic agents Interact to increase 5-HT levels - such as can happen when St John's Wort is taken in combination with an SSRI . REFERENCES
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