Melatonin Synthesis in the Hen Pineal Gland and its Control by Light

MELATONIN (5-methoxy N-acetyltryptamine) has been found to be highly localized in the pineal bodies of a number of mammalian species1,2. The melatonin synthesizing enzyme (hydroxyindole-O-methyl transferase (HIOMT)) has also been found in all mammals examined3, and is present only in the pineal gland4. Evidence has been presented demonstrating that melatonin is secreted by the mammalian pineal and acts on the gonads5. This communication describes the enzymatic synthesis of melatonin in a class other than the mammal: birds. It further demonstrates that the synthesis of melatonin is influenced by lighting, which also affects the bird gonads6.