Melatonin in peripheral nerve

Abstract

MELATONIN is a hormone, isolated from beef pineal glands, that lightens the colour of frog melanocytes either after injection into the frog or after in vitro incubation with pieces of frog skin1. In addition, this hormone can block and reverse the darkening actions of the melanocyte-stimulating hormones and also of adrenocorticotrophic hormone. Melatonin is a 5-hydroxyindole derivative in which the hydroxy group is blocked2. Its melanocyte-lightening properties are more than ten thousand times greater than those of noradrenaline, which previously was considered to be the most potent lightening agent known3. In our early experiments melatonin could be detected only in extracts from pineal glands and not from other tissues. With improvement in extraction techniques we have been able to identify the presence of a lightening agent that is most likely melatonin in peripheral nerves of man, monkey and cow. A detailed mapping of the location of melatonin in the nervous system has not been completed. © 1959 Nature Publishing Group.