Melatonin in the context of the reported bioeffects of environmental electromagnetic fields

This review summarizes the results of studies which tested the possibility that the exposure of mammals to either electric fields, static or sinusoidal magnetic fields, or a combined electromagnetic field, influences the production and secretion of pineal melatonin. The endpoints measured in the reviewed experiments included the activities of the two enzymes involved in the conversion of pineal serotonin to melatonin, namely, N-acetyltransferase (NAT) and hydroxyindole-O-methyltransferase (HIOMT), and pineal and serum melatonin levels. While the results are inconsistent in terms of the ability of the fields to alter melatonin synthesis and secretion, when changes did occur they virtually always involved a suppression in the levels of melatonin. When multiple endpoints were measured in a given experiment, the most consistent change was a reduction in serum levels of the indoleamine. While it has usually been assumed that melatonin synthesis is suppressed by the field exposures, it is proposed that the reduction in serum melatonin (which in some cases was not accompanied by changes in pineal melatonin production) could be a result of an increased uptake and utilization of melatonin as a free radical scavenger in animals exposed to a magnetic field. Copyright (C) 1998 Elsevier Science S.A.