Study type: Medical/biological study (experimental study)

Melatonin protects rat thymus against oxidative stress caused by exposure to microwaves and modulates proliferation/apoptosis of thymocytes. med./bio.

Published in: Gen Physiol Biophys 2013; 32 (1): 79-90

Aim of study (acc. to author)

To examine the effect of a melatonin administration on oxidative stress parameters, DNA fragmentation, apoptosis and proliferation of thymocytes in microwave-exposed rats.

Background/further details

4 groups of rats were examined: 1.) sham exposure, treated with saline injection, 2.) sham exposure, injection of 2 mg melatonin per kg body weight, 3.) exposure and 4.) exposure, injection of 2 mg melatonin per kg body weight (21 rats per group). After 20, 40 and 60 days, seven animals of each group were anesthetized and killed after removing the thymus.

Endpoint

Exposure

Exposure Parameters
Exposure 1: 900 MHz
Exposure duration: continuous for 4 hours/day on 20, 40 or 60 consecutive days

Exposure 1

Main characteristics
Frequency 900 MHz
Type
Charakteristic
Exposure duration continuous for 4 hours/day on 20, 40 or 60 consecutive days
Exposure setup
Exposure source
Setup mobile phone was placed in a small perforated polycarbonated box in the center of the cage; seven freely moving rats per cage were placed on absorbing material made of rubber with wooden isolation surface
Sham exposure A sham exposure was conducted.
Additional info exposure was performed in the same room where all animals were housed or in another room (remark EMF-Portal: contradictory statements)
Parameters
Measurand Value Type Method Mass Remarks
magnetic flux density 4.68 µT minimum estimated - -
magnetic flux density 8.69 µT maximum estimated - -
electric field strength 9.88 V/m minimum estimated - -
electric field strength 18.356 V/m maximum estimated - -
SAR 0.043 W/g minimum estimated - -
SAR 0.135 W/g maximum estimated - -

Exposed system:

Methods Endpoint/measurement parameters/methodology

Investigated system:
Time of investigation:
  • after exposure

Main outcome of study (acc. to author)

In the exposed groups without melatonin (after 20, 40 and 60 days), the level of lipid peroxidation and protein oxidation, as well as the enzyme activities of catalase, xanthine oxidase, DNAse I and DNAse II were significantly increased compared to the control group. An administration of melatonin prevented these effects in the exposed group (except for the protein oxidation after 20 and 40 days).
The number of apoptotic cells was significantly increased in the exposed groups without melatonin compared to the control group. Moreover, the number of apoptotic cells increased with longer exposure duration. An administration of melatonin significantly reduced the apoptosis rate in the exposed group. The proliferation of the thymocytes was significantly decreased in the exposed groups without melatonin in comparison to the control group. This effect was stronger the longer the rats had been exposed. An administration of melatonin significantly increased the proliferation rate in the exposed group when compared to the exposed group without melatonin injection.
The authors conclude that melatonin could have a protective effect against oxidative stress and could modulate processes of apoptosis and proliferation in thymus tissue of microwave-exposed rats.

Study character:

Study funded by

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