Effects of exposure to a circularly polarized 50-Hz magnetic field on plasma and pineal melatonin levels in rats.

We sought to determine whether a 6-week exposure to a 50-Hz rotating magnetic field influences melatonin synthesis by 11-18 week-old Wistar-King male rats. Rats were exposed continuously to a rotating magnetic field at 1, 5, 50, or 250 microT (spatial vector rms) for 6 weeks, except for twice-weekly breaks of about 2 h for cleaning of cages and feeding. The rats were housed in exposure and sham-exposure facilities, which were located in the same room, under a 12:12 light-dark photoperiod (lights on at 06:00 h). The room was constantly illuminated by 4 small, dim red lights (< 0.07 lux in dark period). Levels of plasma and pineal gland melatonin were determined by radioimmunoassay. A significant decrease of melatonin was observed between the control group and groups exposed to a magnetic field at a flux density in excess of 1 microT during the night time, but no statistical differences were found among the exposed groups. These results indicate that subchronic exposure of albino rats to a 50-Hz rotating magnetic field influences melatonin production and secretion by the pineal gland.

[1]  J. Zawilska,et al.  Calcium influx through voltage-sensitive calcium channels regulates in vivo serotonin N-acetyltransferase (NAT) activity in hen retina and pineal gland , 1990, Neuroscience Letters.

[2]  S. Reuss,et al.  Magnetic field effects on the rat pineal gland: Role of retinal activation by light , 1986, Neuroscience Letters.

[3]  R D Phillips,et al.  Chronic exposure to 60-Hz electric fields: effects on pineal function in the rat. , 1981, Bioelectromagnetics.

[4]  H. Schröder,et al.  Magnetic field effects on pineal N-acetyltransferase activity and melatonin content in the gerbil—role of pigmentation and sex , 1988, Physiology & Behavior.

[5]  M. Nozaki,et al.  Diurnal Changes in Serum Melatonin Concentrations Under Indoor and Outdoor Environments and Light Suppression of Nighttime Melatonin Secretion in the Female Japanese Monkey , 1990, Journal of pineal research.

[6]  R. Reiter,et al.  Evidence that extremely low frequency Ca2+-cyclotron resonance depresses pineal melatonin synthesis in vitro , 1991, Neuroscience Letters.

[7]  L. E. Anderson,et al.  Reduction of the nocturnal rise in pineal melatonin levels in rats exposed to 60-Hz electric fields in utero and for 23 days after birth. , 1988, Life sciences.

[8]  L. E. Anderson,et al.  Evidence for an Effect of ELF Electromagnetic Fields on Human Pineal Gland Function , 1990, Journal of pineal research.

[9]  K. Kawashima,et al.  Melatonin in serum and the pineal of spontaneously hypertensive rats. , 1984, Clinical and experimental hypertension. Part A, Theory and practice.

[10]  S. Reuss,et al.  Evidence for the involvement of the visual system in mediating magnetic field effects on pineal melatonin synthesis in the rat , 1985, Brain Research.

[11]  G. Burrows,et al.  Melatonin supersensitivity to dim light in seasonal affective disorder , 1990, The Lancet.

[12]  T. Shigemitsu,et al.  50-Hz magnetic field exposure system for small animals. , 1993, Bioelectromagnetics.

[13]  R. Reiter,et al.  Marked rapid alterations in nocturnal pineal serotonin metabolism in mice and rats exposed to weak intermittent magnetic fields. , 1990, Biochemical and biophysical research communications.

[14]  S. Reuss,et al.  Magnetic field effects on pineal gland melatonin synthesis: comparative studies on albino and pigmented rodents , 1986, Brain Research.

[15]  P A Oberg,et al.  Influence on vision of extremely low frequence electromagnetic fields. Industrial measurements, magnetophosphene studies volunteers and intraretinal studies in animals. , 1979, Acta ophthalmologica.

[16]  R. Reiter,et al.  Pineal gland “magnetosensitivity” to static magnetic fields is a consequence of induced electric currents (eddy currents) , 1991, Journal of pineal research.