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.
Department of Physiology, Hokkaido University School of Medicine, Sapporo, Japan.
M
M
Kato
K
K
Honma
T
T
Shigemitsu
Y
Y
Shiga
D000818:Animals; D002940:Circadian Rhythm / Q000528:radiation effects; D004574:Electromagnetic Fields; D008297:Male; D008550:Melatonin / Q000096:biosynthesis*; D010870:Pineal Gland / Q000378:metabolism* / Q000528:radiation effects; D010953:Plasma Volume / Q000528:radiation effects*; D051381:Rats; D017208:Rats, Wistar; D013997:Time Factors
D008550:Melatonin