Circadian variation in the monoamine Oxidase activity of specific rat brain areas

Abstract The monoamine oxidase (MAO) activity of rat cerebral cortex, cerebellum, hypothalamus, midbrain, pons, medulla oblongata and caudate nucleus was determined every 6h over a 24h period in animals adapted to a 12h dark ‐ 12h light illumination regime. Results show that the MAO activity of the cerebral cortex, hypothalamus, midbrain, pons and caudate nucleus varies diurnally, with the highest and lowest MAO activity in these brain areas occurring during the light and dark phases of the illumination cycle respectively.