Indole Metabolism in the Pineal Gland: A Circadian Rhythm in N-Acetyltransferase

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Science  11 Sep 1970:
Vol. 169, Issue 3950, pp. 1093-1095
DOI: 10.1126/science.169.3950.1093


The activity of N-acetyltransferase in the rat pineal gland is more than 15 times higher at night than during the day. This circadian rhythm persists in complete darkness, or in blinded animals, and is suppressed in constant lighting. The N-acetyltransferase rhythm is 180° out of phase with the serotonin rhythm and is similar to the norepinephrine and melatonin rhythms. Experiments in vitro indicate that norepinephrine, not serotonin, regulates the activity of N-acetyl-transferase through a highly specific receptor.

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