Distribution of endogenous benzodiazepine receptor ligand-monoamine oxidase inhibitory activity (tribulin) in tissues.

The distribution of monoamine oxidase inhibitor-benzodiazepine receptor binding inhibitor, extractable into ethyl acetate at pH 1, was examined in a range of rat tissues. Great variation in the activity of both inhibitors was found in the different tissues, the highest being present in superior cervical ganglion, and lowest in adrenal gland. There was a highly significant correlation between the distribution of the two activities in different tissues, supporting the concept that they both derive from the same molecule (tribulin). The level of inhibitory activity in some of the tissues was such that variations might conceivably play a significant role in vivo.