In a previous study (Selmaoui and Touitou 1995), the authors found that exposure to a 50 Hz magnetic field could suppress the nocturnal peak of melatonin in young rats. Since aging is characterized by a decrease in adaptiveness of the organism to environmental changes, and melatonin levels in old rats are lower than in young ones, the authors hypothesized that old rats might react differently than younger ones.
Rats were divided into the following groups (n=6, respectively): 1) exposure of young rats to the magnetic field, 2) exposure of aged rats to the magnetic field, 3) sham exposure of young rats, 4) sham exposure of aged rats. After exposure, all rats were killed and investigated.
Exposure duration: 18 hours/day for 1 week
|Setup||eight shelves were equipped with an exposure system (6 rectangular coils) programmed to switch the field on and off at 14:00 and 08:00, respectively; sham exposed and exposed animals were handled and maintained simultaneously under the same conditions; the MF was uniform in all exposure boxes without any interaction between them; sham exposed animals were kept sufficiently spaced from exposed ones to avoid any interaction|
|Sham exposure||A sham exposure was conducted.|
|magnetic flux density||100 µT||-||-||-||-|
Exposure to the magnetic field resulted in a significant decrease in serum melatonin and serotonin N-acetyltransferase enzyme activity in young rats (group 1) compared to their sham exposure group (group 3).
In aged rats, no significant effects of exposure to the magnetic field were observed. However, serum melatonin levels and N-acetyltransferase enzyme activity were decreased in sham exposed aged rats (group 4) compared to sham exposed young rats (group 3) (decrease by about 38% and 36%, respectively) confirming the generally lower melatonin levels in aged rats.
The authors conclude that exposure to a 50 Hz magnetic field might attenuate pineal gland function in young rats, while aged rats seem to be insensitive.