The purpose of this research is to explore possible mechanisms underlying the neurochemical, behavioral, neuroendocrine, and physiological effects of various beta-carboline compounds. This involves the ability of these compounds to do the following: (1) elevate brain serotonin (5-hydroxytryptamine, 5-HT); (2) inhibit monoamine oxidase (MAO); (3) block the synaptosomal uptake of 5-HT; (4) produce a retention deficit for one-trial passive avoidance behavior; (5) block and produce seizures; (6) elevate plasma corticosterone and prolactin; (7) lower locomotor activity. These effects are dependent upon the structures of the Beta-carboline compounds. Our studies for the coming year will involve effects of Beta-carbolines on the following: brain serotonin synthesis; brain catecholamines; plasma prolactin; audiogenic seizures; and operant conditioning. In conducting these studies we use radioisotopic, differential centrifugation, spectrophotofluorometric, chromatographic, and behavioral techniques. These should allow us to make accurate correlations between neurochemical changes and related behavioral manifestations produced by the Beta-carboline compounds. BIBLIOGRAPHIC REFERENCES: Buckholtz, N.A. and Boggan, W.O. Effects of Tetrahydro-Beta-carbolines on Monoamine Oxidase and Serotonin Uptake in Mouse Brain. Biochem. Pharmacol., 1976, 25, 2319-2321. Meyer, J.S. and Buckholtz, N.S. Effects of Beta-Carbolines on Plasma Corticosterone in Mice. Res. Comm. Chem. Path. Pharmacol., 1976, 14, 205-213.