Medical/biological study (experimental study)

Evaluation of oxidant stress and antioxidant defense in discrete brain regions of rats exposed to 900 MHz radiation med./bio.

By: Narayanan SN, Kumar RS, Kedage V, Nalini K, Nayak S, Bhat PG

Published in: Bratisl Lek Listy 2014; 115 (5): 260-266

PubMed

Aim of study (acc. to author)

The effects of a whole body exposure of adolescent rats to a 900 MHz electromagnetic GSM field on oxidative stress and the antioxidative system in discrete brain sections should be investigated.

Background/further details

36 rats were equally separated into the three following groups (n=12 in each group): 1) cage control, 2) sham exposure and 3) exposure. Subsequent to exposure (day 29), behavioral analysis was conducted (not part of the present paper, published here: Narayanan et al. 2013) and afterwards, six animals of each group were sacrificed and examined.

Endpoint

effects on the neurological system: oxidative stress in the brain

Exposure

- 900 MHz
- mobile communications
- mobile phone
- GSM

Exposure	Parameters
Exposure 1: 890–915 MHz Modulation type: pulsed Exposure duration: intermittent for 1 h/day for 28 days	SAR: 1.58 W/kg (according to manufacturer) power density: 146.6 µW/cm² peak value (3 cm away from the phone during incoming call) power density: 2.109 nW/cm² peak value (3 cm away from the phone in "ON" mode during pause intervals)

Exposure 1

Main characteristics

Frequency	890–915 MHz
Type	electromagnetic field
Exposure duration	intermittent for 1 h/day for 28 days

Modulation

Modulation type	pulsed
Repetition frequency	217 Hz

Exposure setup

Exposure source	cellular phone
Chamber	polypropylene cages (3 animals per cage) measuring 41 cm Œ 28 cm Œ 14 cm, temperature 23°C ± 2°C
Setup	phone in silence mode was placed in a wood bottom bamboo wire mesh cage (12 cm Œ 7 cm Œ 7 cm) in the center of the home cage with 3 rats; daily exposure composed of 50 unattended calls within 1 hour, each lasting for 45 seconds, followed by a 15-second pause interval before next call
Sham exposure	A sham exposure was conducted.

Parameters

Measurand	Value	Type	Method	Mass	Remarks
SAR	1.58 W/kg	-	-	-	according to manufacturer
power density	146.6 µW/cm²	peak value	measured	-	3 cm away from the phone during incoming call
power density	2.109 nW/cm²	peak value	measured	-	3 cm away from the phone in "ON" mode during pause intervals

Reference articles

Narayanan SN et al. (2013): Analysis of emotionality and locomotion in radio-frequency electromagnetic radiation exposed rats
Narayanan SN et al. (2010): Effect of radio-frequency electromagnetic radiations (RF-EMR) on passive avoidance behaviour and hippocampal morphology in Wistar rats

Exposed system:

animal
rat/Wistar albino
whole body

Methods Endpoint/measurement parameters/methodology

molecular biosynthesis: total protein concentration in single brain regions (Bradford protein assay)
effects on the neurological system: oxidative stress in single brain regions: lipid peroxidation (with thiobarbituric acid reactive substances (TBARS)), total antioxidative activity (capacity of sample to inhibit the production of TBARS from sodium benzoate), glutathione S-transferase enzyme activity (reaction with Ellman's reagent) (spectrophotometry)

Investigated system:

isolated organ
supernatants of tissue lysates

Investigated organ system:

Time of investigation:

after exposure

Main outcome of study (acc. to author)

The level of thiobarbituric acid reactive substances was significantly increased in samples of exposed animals compared to sham exposure and cage control in all investigated brain regions. Moreover, exposure samples showed a significant decrease in the total antioxidative activity in the amygdala and cerebellum but it was not significantly changed in other brain regions. Glutathione S-transferase enzyme activity was significantly decreased in the hippocampus in the exposure group compared to sham exposure and cage control, but it was unaltered in other brain regions studied.
The authors conclude that an exposure of rats to a 900 MHz electromagnetic GSM field causes oxidative stress with regional differences in rat brain, which might be related to behavioral changes observed in Narayanan et al. 2013.

Study character:

medical/biological study
experimental study
pilot/exploratory/preliminary study
blind study

Study funded by

Indian Council of Medical Research (ICMR), India

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