The mice were exposed for 52 days and nocturnal urine was collected 1, 3, 7, 14, 16, and 23 days after the beginning of magnetic field exposure. The animal room was illuminated for 12 h daily at 200 lux. To study the circadian rhythm of melatonin production, night and day samples of urine were collected once (at about 40 days after the beginning of exposure).
Exposure duration: continuous for 52 days
|Setup||Animals were housed in polycarbonate cages with lids made of steel wire. Sham exposed animals were in an identical but non energized system in the same room. The exposure system consisted of two paired exposure racks with five coils (0.4 x 1.2 m) in each to produce vertical magnetic field. The vertical distance among the five coils were 0.25 m.|
|magnetic flux density||100 µT||unspecified||measured||-||-|
No statistically significant peak of melatonin was found in either group. The light-regulated natural melatonin rhythm was absent in sham-exposed animals. The magnetic field exposure caused a significant day-night difference in the 6-OHMS levels, but did not affect the total excretion of 6-OHMS during the 24-hour period.
A possible interpretation of the results is that magnetic field exposure increases the sensitivity of the pineal gland to light in this strain normally insensitive to the circadian light variations.