Melatonin content in the rat pineal decreases at night after exposure of animals to light, from 20 to 2 pmol/gland in 15 min. Melatonin concentration in serum fell precipitously in a manner almost identical to the drop in pineal melatonin only with a 5 min time lag. It is concluded that the rapid decrease in the pineal melatonin content is mainly due to an inhibited synthesis of melatonin.

Institute of Physiology Czechoslovak Academy of Sciences 142 20 Prague 4 Czechoslovakia

References provided by Crossref.org

From the Pineal Gland to the Central Clock in the Brain: Beginning of Studies of the Mammalian Biological Rhythms in the Institute of Physiology of the Czech Academy of Sciences

Entrainment of the circadian rhythm in the rat pineal N-acetyltransferase activity by prolonged periods of light