Serotonin is a neurotransmitter. Its chemical name is 5-Hydroxytryptamine or 5-HT. It is derived from tryptophan. Serotonin is found in all vertebrates, mainly in the gastrointestinal tract, blood platelets and central nervous system. Its name is derived from its effect on blood pressure: serotonin is a part of the serum which regulates the tonus of blood vessels.

Serotonin does several jobs within the human body. It is believed to regulate mood, intestinal activity and appetite, memory, and sleep. Many antidepressant medications are thought to work by increasing the levels of serotonin in the body.[1][2] Some non-medical treatments for depression have also been shown to raise serotonin levels.[3]

Serotonin is also found in insect venom, fungi and plants.[4] Its presence in the seeds of many fruits helps speed those seeds through the digestive tract of animals that consume them.[5] In insect venom, it causes pain, and sometimes death, through its effect on smooth muscle contraction.[6]

Serotonin is involved in social rank. A lobster injected with serotonin behaves like an alpha.[7]


  1. "Selective serotonin reuptake inhibitors (SSRIs)". Mayo Clinic. Retrieved 2018-05-30.
  2. Stahl, S. M. (1998-12). "Mechanism of action of serotonin selective reuptake inhibitors. Serotonin receptors and pathways mediate therapeutic effects and side effects". Journal of Affective Disorders 51 (3): 215–235. ISSN 0165-0327. PMID 10333979. 
  3. Young, Simon N. (2007-11). "How to increase serotonin in the human brain without drugs". Journal of Psychiatry & Neuroscience : JPN 32 (6): 394–399. ISSN 1180-4882. PMC PMC2077351. PMID 18043762. 
  4. Kang K, Park S, Kim YS, Lee S, Back K (2009). "Biosynthesis and biotechnological production of serotonin derivatives". Appl. Microbiol. Biotechnol. 83 (1): 27–34. doi:10.1007/s00253-009-1956-1. PMID 19308403. 
  5. "Serotonin in Plants". 2009-12-11. Retrieved 2018-05-30.
  6. Inglis-Arkell, Esther. "Why is There Serotonin in Animal Venom?". io9. Retrieved 2018-05-30.
  7. Kravitz, E. A. (30 September 1988). "Hormonal control of behavior: amines and the biasing of behavioral output in lobsters". Science 241 (4874): 1775–1781. doi:10.1126/science.2902685. PMID 2902685.