Editing Tryptamine (section)

=== Serotonin receptor agonist ===
Tryptamine is known to act as a [[serotonin receptor]] [[agonist]], although its [[potency (pharmacology)|potency]] is limited by rapid [[catabolism|inactivation]] by [[monoamine oxidase]]s.<ref name="Jones1982" /><ref name="BloughLandavazoDecker2014" /><ref name="Mousseau1993">{{cite journal | vauthors = Mousseau DD | title = Tryptamine: a metabolite of tryptophan implicated in various neuropsychiatric disorders | journal = Metab Brain Dis | volume = 8 | issue = 1 | pages = 1–44 | date = March 1993 | pmid = 8098507 | doi = 10.1007/BF01000528 | url = }}</ref><ref name="AnwarFordBroadley2012">{{cite journal | vauthors = Anwar MA, Ford WR, Broadley KJ, Herbert AA | title = Vasoconstrictor and vasodilator responses to tryptamine of rat-isolated perfused mesentery: comparison with tyramine and β-phenylethylamine | journal = Br J Pharmacol | volume = 165 | issue = 7 | pages = 2191–2202 | date = April 2012 | pmid = 21958009 | pmc = 3413856 | doi = 10.1111/j.1476-5381.2011.01706.x | url = }}</ref><ref name="BradleyHumphreyWilliams1985">{{cite journal | vauthors = Bradley PB, Humphrey PP, Williams RH | title = Tryptamine-induced vasoconstrictor responses in rat caudal arteries are mediated predominantly via 5-hydroxytryptamine receptors | journal = Br J Pharmacol | volume = 84 | issue = 4 | pages = 919–925 | date = April 1985 | pmid = 3159458 | pmc = 1987057 | doi = 10.1111/j.1476-5381.1985.tb17386.x | url = }}</ref> It has specifically been found to act as a [[full agonist]] of the [[serotonin]] [[5-HT2A receptor|5-HT<sub>2A</sub> receptor]] ({{Abbrlink|EC<sub>50</sub>|half-maximal effective concentration}} = 7.36 ± 0.56{{nbsp}}nM; [[intrinsic activity|E<sub>max</sub>]] = 104 ± 4%).<ref name="BloughLandavazoDecker2014" /> Tryptamine was of much lower potency in stimulating the 5-HT<sub>2A</sub> receptor [[β-arrestin]] pathway ({{Abbr|EC<sub>50</sub>|half-maximal effective concentration}} = 3,485 ± 234{{nbsp}}nM; E<sub>max</sub> = 108 ± 16%).<ref name="BloughLandavazoDecker2014" /> In contrast to the 5-HT<sub>2A</sub> receptor, tryptamine was found to be inactive at the serotonin [[5-HT1A receptor|5-HT<sub>1A</sub> receptor]].<ref name="BloughLandavazoDecker2014" />

==== Gastrointestinal motility ====
Tryptamine produced by mutualistic bacteria in the human gut activates serotonin GPCRs ubiquitously expressed along the colonic epithelium.<ref name=":103"/> Upon tryptamine binding, the activated 5-HT<sub>4</sub> receptor undergoes a conformational change which allows its [[Gs alpha subunit|G<sub>s</sub> alpha subunit]] to exchange [[Guanosine diphosphate|GDP]] for [[Guanosine triphosphate|GTP]], and its liberation from the 5-HT<sub>4</sub> receptor and βγ subunit.<ref name=":103" /> GTP-bound G<sub>s</sub> activates [[adenylyl cyclase]], which catalyzes the conversion of [[Adenosine triphosphate|ATP]] into [[cyclic adenosine monophosphate]] (cAMP).<ref name=":103" /> cAMP opens chloride and potassium ion channels to drive colonic electrolyte secretion and promote intestinal motility.<ref name=":152"/><ref>{{Cite web|date=2018-06-15|title=Microbiome-Lax May Relieve Constipation|url=https://www.genengnews.com/topics/omics/microbiome-lax-may-relieve-constipation/|access-date=2020-12-11|website=GEN - Genetic Engineering and Biotechnology News|language=en-US}}</ref>

[[File:Tryptamine_mechanism_of_action_in_the_human_gut.png|thumb|none|550px|Tryptamine promotes intestinal motility by activating serotonin receptors in the gut to increase colonic secretions.]]