Medical/biological study (experimental study)

Melatonin reduces oxidative stress induced by chronic exposure of microwave radiation from mobile phones in rat brain med./bio.

By: Sokolovic D, Djindjic B, Nikolic J, Bjelakovic G, Pavlovic D, Kocic G, Krstic D, Cvetkovic T, Pavlovic V

Published in: J Radiat Res 2008; 49 (6): 579-586

Aim of study (acc. to author)

To study the intensity of oxidative stress in the brain of animals chronically exposed to cell phones and potential protective effects of melatonin in reducing oxidative stress and brain injury.

Background/further details

Experiments were performed on 84 adult male rats exposed to microwave irradiation during 20, 40 and 60 days (4 hours/day during light period). Four groups (each 21 animals) were formed: 1) control-rats treated daily by saline, 2) rats treated daily with melatonin (2 mg/kg body weight), 3) microwave exposed rats and 4) microwave exposed rats treated with melatonin (2 mg/kg body weight).

Endpoint

effects on the neurological system: oxidative stress in the brain

Exposure

- microwaves
- mobile communications
- digital mobile phone
- GSM

Exposure	Parameters
Exposure 1: 900 MHz Modulation type: CW Exposure duration: repeated daily exposure, 4 h/day, for 20, 40, and 60 days	electric field strength: 18.356 V/m (9.88-18.356 V/m) magnetic flux density: 8.69 µT (4.68-8.69 µT) SAR: 0.135 W/kg average over mass (whole body) (0.043-0.135 W/kg)

Exposure 1

Main characteristics

Frequency	900 MHz
Type	electromagnetic field
Charakteristic	near field
Exposure duration	repeated daily exposure, 4 h/day, for 20, 40, and 60 days

Modulation

Modulation type	CW

Exposure setup

Exposure source	cellular phone connected to a communication tester
Chamber	Seven animals were housed and exposed collectively in pure polycarbonate cages of 30 Œ 40 Œ 40 cm (W Œ L Œ H).
Setup	Every four hours, two cages from the MW and MW+Mel groups were transferred to a wooden desk with rubber surface placed at 5 m from the housed rats, and a mobile test phone was put in a small perforated polycarbonate cell in the center of each cage preventing damage caused by rats.
Sham exposure	A sham exposure was conducted.
Additional info	Two dummy phones were put in the control and Mel group cages at the same time.

Parameters

Measurand	Value	Type	Method	Mass	Remarks
electric field strength	18.356 V/m	-	measured	-	9.88-18.356 V/m
magnetic flux density	8.69 µT	-	measured	-	4.68-8.69 µT
SAR	0.135 W/kg	average over mass	calculated	whole body	0.043-0.135 W/kg

Measurement and calculation details

Electromagnetic field parameters in the cage were measured several times during exposure using an EM field meter. The whole-body SAR was estimated using data for a rotating ellipsoidal model of a rat.

Exposed system:

animal
rat/Wistar albino
whole body

Methods Endpoint/measurement parameters/methodology

effects on the neurological system: oxidative stress in the brain: malondialdehyde concentration (index for lipid peroxidation), protein oxidation (carbonyl group concentration) and activity of antioxidative enzyme catalase, activity of xanthine oxidase enzyme (spectrophotometry) and brain proteins (Lowry method)

Investigated system:

brain homogenates

Investigated organ system:

brain/CNS

Time of investigation:

after exposure

Main outcome of study (acc. to author)

A significant increase in the brain tissue malondialdehyde and carbonyl group concentration was registered during the whole exposure. Decreased enzyme activity of catalase and increased activity of xanthine oxidase remained after 40 and 60 days of exposure to mobile phones. Melatonin treatment significantly prevented the increase in the malondialdehyde content and xantine oxidase activity in the brain after 40 days of exposure while it was unable to prevent the decrease of catalase activity and increase of carbonyl group contents.
Mobile phones caused oxidative damage biochemically by increasing the levels of malondialdehyde, carbonyl groups, xanthine oxidase and decreasing catalase enzyme activity. Treatment with the melatonin significantly prevented oxidative damage in the brain.

Study character:

medical/biological study
experimental study
full/main study

Study funded by

not stated/no funding

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