Serotonin, or 5-hydroxytryptamine (5-HT), is a biogenic monoamine neurotransmitter, derived from the amino acid tryptophan, found in numerous animal venoms. In the human body, serotonin is found mainly in the gastrointestinal tract, the central nervous system, and in platelets. It is involved in the regulation of mood, appetite, and sleep.
When present in venoms, serotonin serves a defensive purpose. Its role in the contraction of smooth muscles (such as the abdominal smooth muscles during digestion) means that a sudden increase in the body, as in the process of envenomation, leads to severe local pain or even lethal vasoconstriction in the case of smaller prey. Serotonin is also understood to facilitate the spread and absorption of the more toxic components in venoms.
Beck, D.D. (2005). Biology of Gila Monsters and Beaded Lizards (Organisms and Environments). University of California Press. 247.
Welsh J.H., Batty C.S. (1963). 5-Hydroxytryptamine content of some arthropod venoms and venom containing parts. Toxicon 1:165.
. The level of serotonin present in apitoxin (honey bee venom) varies with age. Worker bees more than three weeks old were found have two to three times more serotonin present in their venom than workers five to ten days old.