Circadian Rhythm in Pineal Serotonin: Effect of Monoamine Oxidase Inhibition and Reserpine

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Science  30 Jul 1965:
Vol. 149, Issue 3683, pp. 542-543
DOI: 10.1126/science.149.3683.542


The pineal gland of the rat shows a circadian rhythm in its serotonin content, the amount of serotonin decreasing at night. This decrease can be prevented by inhibiting the action of monoamine oxidase. Reserpine abolishes the circadian rhythm in pineal serotonin in the same manner as does interruption of the sympathetic nervous connections of the central nervous system and the pineal gland. These observations suggest that circadian changes in release and binding of serotonin may occur in the pineal gland, and that a central mechanism in which monoamines participate may control the circadian pineal-serotonin rhythm.