title: beta-Carbolines and Tetrahydroisoquinolines: Detection and Function in Mammals.
abstract: beta-Carbolines occur in man and rat. The concentration in various tissues is about 100 to 1000 times lower than that of classical neurotransmitters. Administration of beta-carbolines in animals induces overlapping but not identical activity profiles. The molecular modes of action differ. For example, harman (1-methyl-beta-carboline) acts as an endogenous inhibitor of monoamine oxidase [E.C. 1.4.3.4.], subtype A, whereas norharman (beta-carboline) probably acts by stimulation of a specific beta-carboline receptor which is different from the benzodiazepine-GABA receptor complex. There is substantial evidence that tetrahydroisoquinolines occur under physiological conditions as well. Whether tetrahydropapaveroline serves as a precursor of morphinanes in mammals, as has been found in opium poppies, remains to be elucidated.
authors.affiliation: Department of Neuropsychopharmacology, Free University, Ulmenallee 30, D-1000 Berlin 19, Federal Republic of Germany.
authors.forename: H
authors.initials: H
authors.lastname: Rommelspacher
authors.forename: T
authors.initials: T
authors.lastname: May
authors.forename: R
authors.initials: R
authors.lastname: Susilo