Medical/biological study (experimental study)

Age-related differences in serum melatonin and pineal NAT activity and in the response of rat pineal to a 50-Hz magnetic field med./bio.

By: Selmaoui B, Touitou Y

Published in: Life Sci 1999; 64 (24): 2291-2297

Aim of study (acc. to author)

The effects of exposure of young and aged rats to a 50 Hz magnetic field on the pineal gland should be investigated.

Background/further details

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.

Endpoint

endocrine changes: serum melatonin level and enzyme activities in the pineal gland

Exposure

Exposure	Parameters
Exposure 1: 50 Hz Exposure duration: 18 hours/day for 1 week	magnetic flux density: 100 µT

Exposure 1

Main characteristics

Frequency	50 Hz
Type	magnetic field
Waveform	sinusoidal
Exposure duration	18 hours/day for 1 week

Exposure setup

Exposure source	coil(s)
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.

Parameters

Measurand	Value	Type	Method	Mass	Remarks
magnetic flux density	100 µT	-	-	-	-

Additional parameter details

the magnetic field generation and continuous monitoring were computer controlled; background magnetic field was about 10 nT

Reference articles

Selmaoui B et al. (1995): Sinusoidal 50-Hz magnetic fields depress rat pineal NAT activity and serum melatonin. Role of duration and intensity of exposure

Exposed system:

Methods Endpoint/measurement parameters/methodology

endocrine changes: serum melatonin level (radioimmunoassay) and enzyme activities in the pineal gland (serotonin N-acetyltransferase and hydroxyindole-O-methyltransferase; radioenzymatic assay)

Investigated system:

isolated bio./chem. substance
isolated organ
blood, pineal gland

Investigated organ system:

endocrine system

Time of investigation:

after exposure

Main outcome of study (acc. to author)

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.

Study character:

medical/biological study
experimental study
full/main study

Study funded by

not stated/no funding

Dyche J et al. (2012): Effects of power frequency electromagnetic fields on melatonin and sleep in the rat
Bakos J et al. (2002): One week of exposure to 50 Hz, vertical magnetic field does not reduce urinary 6-sulphatoxymelatonin excretion of male wistar rats
Chacon L (2000): 50-Hz Sinusoidal Magnetic Field Effect On In Vitro Pineal N-Acetyltransferase Activity
Heikkinen P et al. (1999): Chronic exposure to 50-Hz magnetic fields or 900-MHz electromagnetic fields does not alter nocturnal 6-hydroxymelatonin sulfate secretion in CBA/S mice
Yellon SM et al. (1998): Melatonin rhythm onset in the adult siberian hamster: influence of photoperiod but not 60-Hz magnetic field exposure on melatonin content in the pineal gland and in circulation
Loscher W et al. (1998): Exposure of female rats to a 100-microT 50 Hz magnetic field does not induce consistent changes in nocturnal levels of melatonin
Bakos J et al. (1997): Urinary 6-sulphatoxymelatonin excretion is increased in rats after 24 hours of exposure to vertical 50 Hz, 100 microT magnetic field
Truong H et al. (1997): Effect of various acute 60 Hz magnetic field exposures on the nocturnal melatonin rise in the adult Djungarian hamster
Mevissen M et al. (1996): Study on pineal function and DMBA-induced breast cancer formation in rats during exposure to a 100-mG, 50 Hz magnetic field
Yellon SM (1996): 60-Hz magnetic field exposure effects on the melatonin rhythm and photoperiod control of reproduction
Selmaoui B et al. (1995): Sinusoidal 50-Hz magnetic fields depress rat pineal NAT activity and serum melatonin. Role of duration and intensity of exposure
Rogers WR et al. (1995): Regularly scheduled, day-time, slow-onset 60 Hz electric and magnetic field exposure does not depress serum melatonin concentration in nonhuman primates
Bakos J et al. (1995): Sinusoidal 50 Hz, 500 microT magnetic field has no acute effect on urinary 6-sulphatoxymelatonin in Wistar rats
Loscher W et al. (1994): Effects of weak alternating magnetic fields on nocturnal melatonin production and mammary carcinogenesis in rats
Kato M et al. (1994): Horizontal or vertical 50-Hz, 1-microT magnetic fields have no effect on pineal gland or plasma melatonin concentration of albino rats
Kato M et al. (1993): Effects of exposure to a circularly polarized 50-Hz magnetic field on plasma and pineal melatonin levels in rats
Welker HA et al. (1983): Effects of an artificial magnetic field on serotonin N-acetyltransferase activity and melatonin content of the rat pineal gland