Hydrogen Peroxide Production by Rat Brain In Vivo

Abstract

H2 O2 production by rat brain in vivo was observed with a method based on the measurement of brain catalase. The administration to the rat of 3‐amino‐1, 2, 4‐triazole, an H2 O2‐ dependent inhibitor of catalase, caused progressive inhibition of brain catalase activity in both the supernatant and pellet fractions of homogenates of the striatum and prefrontal cortex. The prevention of catalase inhibition by prior administration of ethanol confirmed that catalase inhibition in vivo was dependent upon H2 O2. A significant portion of the catalase (30‐33%) appeared in the supernatant fraction from a slow‐speed homogenization procedure and was not significantly contaminated by either erythrocytes or capillaries. In the whole homogenate, less than 6% of the catalase activity was attributed to erythrocytes. Modification of intracellular monoamine oxidase activity by either pargyline or reserpine did not change the rate of inhibition of catalase by aminotriazole. A probable interpretation of these data is that H2 O2 generated by mitochondrial monoamine oxidase does not reach the catalase compartment; the catalase is contained in particles described by other investigators as the microperoxisomes of brain. In studies in vitro, the production of H2 O2 by rat brain mitochondria with either dopamine or serotonin as substrate was confirmed.

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