Serotonin (5-hydroxytryptamine, or 5-HT) is a monoamine neurotransmitter synthesized in serotonergic neurons in the central nervous system (CNS) and enterochromaffin cells in the gastrointestinal tract. The neurons in the brain that release serotonin are found in small dense collections of neurons called Raphe Nuclei. The Raphe Nuclei are found in the medulla, pons and midbrain which are all located at the top of the spinal cord. Serotonergic neurons have axons which project to many different parts of the brain, therefore serotonin affects (Rosling, Claire, 2004). In the body, serotonin is synthesized from the amino acid tryptophan by the activity of the enzymes Tryptophan hydroxylase (TPH) and Amino acid decarboxylase (DDC) (Dolnak, Douglas R. DO, 2006). The enzyme tryptophan hydroxylase adds a hydroxyl group to tryptophan's benzene ring at position 5, creating 5-hydroxytryptophan. Another enzyme, amino acid decarboxylase, then removes a carboxyl group from 5-hydroxytryptophan, forming 5-hydroxytryptamine which is more commonly known as serotonin. The average adult human possesses only 5 to 10 mg of serotonin, 90 % of which is in the intestine and the rest in blood platelets and the brain (Rosling, Claire, 2004). Stimuli necessary for secretion
Serotonin is known to cause vasoconstriction and cellular proliferation in pulmonary arteries. Levels of serotonin are elevated in the plasma of patients with primary pulmonary arterial hypertension (Hippisley-Cox, Julia; Katherine Fielding, and Mike Pringle, 1998). Serotonin is also secreted in excess by carcinoid tumours. Some foods such as bananas, pineapples and walnuts contain serotonin and can increase the excretion of 5-HIAA (Maroteaux, Luc and Canan G. Nebigil, 2003). Studies have shown that serotonin levels are increased with increased exercise and the production of serotonin is increased for some days after the activity (Rosling, Claire, 2004). Serotonin levels...
Bibliography: Buck, Marcia L. Serotonin Syndrome: Pediatric and Neonatal Considerations Pediatric Pharmacotherapy. Newsletter for Health Care Professionals from the University of Virginia Children 's Hospital. 12: 3; March 2006
Cowen, P.J. Cortisol, Serotonin, and Depression: All Stressed Out?. British Journal of Psychiatry 180: 99-100; 2002
Dolnak, Douglas R. DO. Treating Patients for Comorbid Depression, Anxiety Disorders, and Somatic Illnesses. J Am Osteopath Assoc. 2006;106(Suppl 2):S9–S14.
G. M. Mawe; M. D. Coates; P. L. Moses. Review Article: Intestinal Serotonin Signalling in Irritable Bowel Syndrome. Alimentary Pharmacology & Therapeutics. 2006;23(8):1067-1076.
Hippisley-Cox, Julia; Katherine Fielding, and Mike Pringle. Depression as a risk factor for ischaemic heart disease in men: population based casecontrol study. BMJ:General Practice 1998;316:1714–9
Hong, Zhigang, Irene M. Lang, Anthony Varghese and E. Kenneth Weir. Increased release of serotonin from rat ileum due to dexfenfluramine. Am J Physiol Regulatory Integrative Comp Physiol 287:1209-1213, 2004. First published Jul 8, 2004;
Maroteaux, Luc and Canan G.Nebigil. Functional Consequences of Serotonin/5-HT2B Receptor Signaling in Heart: Role of Mitochondria in Transition Between Hypertrophy and Heart Failure?. Circulation 2003; 108; 902-908.
Rosling, Claire. Serotonin: A Molecule of Happiness. University of Bristol. Available on the World Wide Web http://www.chm.bris.ac.uk/motm/serotonin/home1.htm. accessed 25Nov 2006.
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