50-Hz sinusoidal magnetic field effect on in vitro pineal N-acetyltransferase activity

Some studies have shown a decrease in pineal N-acetyltransferase (NAT) acti vity and/or blood melatonin concentration in rodents exposed to extremely l ow-frequency (ELF) and low magnetic flux density electromagnetic fields. Th e mechanism/s involved in such effects are not known. It has been hypothesi zed that the magnetic fields (MF) could act on the pineal gland directly an d/or indirectly through the retina. The aim of this work was to study wheth er MFs could modify NAT activity through a direct effect on the gland. Pine al glands obtained from rats sacrificed in the middle of the dark period we re exposed during a 1-h incubation to 10-, 100-, or 1,000-muT, 50-Hz, sinus oidal MFs. The results showed that the glands exposed to the highest magnet ic flux density responded with a significant decrease in NAT activity. The data obtained from these experiments support the idea that the pineal gland can be directly affected by ELF electromagnetic fields.