Bufotenine and N,N‐dimethyltryptamine (DMT) are hallucinogenic dimethylated indolethylamines (DMIAs) formed from serotonin and tryptamine by the enzyme indolethylamine N‐methyltransferase (INMT) ubiquitously present in non‐neural tissues. In mammals, endogenous bufotenine and DMT have been identified only in human urine. The DMIAs bind effectively to 5HT receptors and their administration causes a variety of autonomic effects, which may reflect their actual physiological function. Endogenous levels of bufotenine and DMT in blood and a number of animal and human tissues were determined using highly sensitive and specific quantitative mass spectrometric techniques. A new finding was the detection of large amounts of bufotenine in stools, which may be an indication of its role in intestinal function. It is suggested that fecal and urinary bufotenine originate from epithelial cells of the intestine and the kidney, respectively, although the possibility of their synthesis by intestinal bacteria cannot be excluded. Only small amounts of the DMIAs were found in somatic or neural tissues and none in blood. This can be explained by rapid catabolism of the DMIAs by mitochondrial monoamino‐oxidase or by the fact that the dimethylated products of serotonin and tryptamine are not formed in significant amounts in most mammalian tissues despite the widespread presence of INMT in tissues.

Hallucinogenic tryptamines have also been identified in animals, including humans.

Bufotenine, 5-methoxy-N,N-dimethyltryptamine, and DMT, as well as tryptamine and N-methyl-tryptamine, have been identified as endogenous metabolites in rats and other mammals, including humans. N-methyl transferases and other enzymes capable of catalyzing the biosynthesis of catabolism of hallucinogenic tryptamines have been characterized in human lung, brain, blood, cerebrospinal fluid, liver, and heart, as well as in these and other tissues in other species. Barker et al. have speculated on the possible neuromodulatory and/or neuroregulatory role of endogenous DMT in mammalian systems, and Callaway has presented an interesting hypothesis regarding the possible role of endogenous DMT and ß-carbolines in the regulation of REM sleep.