5-Methoxytryptamine (aka 5-MT, mexamine) is a tryptamine derivative closely related to the neurotransmitters serotonin and melatonin. 5-MT is produced endogenously at low levels; it is biosynthesized by deacetylation of melatonin in the pineal gland. 5-MT acts as a full agonist at the 5-HT1, 5-HT2, 5-HT4, 5-HT6, and 5-HT7 receptors. It is often used as a chemical probe in the study of serotonin receptors, but it has also been used in a clinical trial to mitigate the anemic effects of cisplatin chemotherapy.