Medical/biological study (experimental study)

Gender and Age Differences in the Suppressive Effect of a 50 Hz Electric Field on the Immobilization-Induced Increase of Plasma Glucocorticoid in Mice med./bio.

By: Harakawa S, Hori T, Nedachi T, Suzuki H

Published in: Bioelectromagnetics 2020; 41 (2): 156-163

Aim of study (acc. to author)

The suppressive effect of exposure to a 50 Hz electric field on immobilization-induced increase in glucocorticoid level in mice of different age and sex should be invesigated.

Background/further details

Glucocorticoid levels were measured as an indicator for stress. There were 4 different treatments: 1) immobilization and electric field exposure, 2) electric field exposure only, 3) immobilization only, 4) control group. Respectively, a) 6 female mice, b) 6 female mice with ovariectomy, c) 6 young (10 weeks) male mice, d) 6 young (15 weeks) male mice, e) 6 adult (25 weeks) male mice and f) 6 older (55 weeks) male mice were subjected to these treatments and thus a total of 24 different groups were formed (1a-4f). Immobilization stress was applied during the second half (30 min) of the 60‐min exposure period.

Endpoint

effects on blood parameters and glucocorticoid level in plasma

Exposure

Exposure	Parameters
Exposure 1: 50 Hz Exposure duration: 60 minutes	electric field strength: 10 kV/m (± 4% outside the exposure cage and ± 0.1% inside) magnetic flux density: 12 nT (± 4 nT)

Exposure 1

Main characteristics

Frequency	50 Hz
Type	electric field
Exposure duration	60 minutes

Exposure setup

Exposure source	electrode
Chamber	cylindrical plastic cage (diameter: 200 mm; height: 100 mm) with slits (length: 100 mm; width: 5 mm) all around at intervals of 5 mm; the temperature inside the cage was 25 ± 3 °C during the exposure or sham exposure; the humidity was maintained between 45% and 55%; stress was applied by immobilizing each mouse separately within a 50‐ml centrifuge (polypropylene) tube or in immobilization devices; immobilization devices were used in different sizes for different ages of mice
Setup	a parallel plate electrode system comprising two stainless steel electrodes (1,000 × 600 mm) that were placed over and under the cylindrical exposure cage; to generate the electric field of 10 kV/m in the cage, 1 kV was applied to the upper electrode, whereas the counterpart electrode was grounded
Sham exposure	A sham exposure was conducted.

Parameters

Measurand	Value	Type	Method	Mass	Remarks
electric field strength	10 kV/m	-	measured	-	± 4% outside the exposure cage and ± 0.1% inside
magnetic flux density	12 nT	-	measured	-	± 4 nT

Measurement and calculation details

electric field intensity was measured at 273 arbitrary points (21 × 13) on each cage floor

Reference articles

Hori T et al. (2018): Characterization of the suppressive effects of extremely-low-frequency electric fields on a stress-induced increase in the plasma glucocorticoid level in mice
Harakawa S et al. (2017): Time-dependent changes in the suppressive effect of electric field exposure on immobilization-induced plasma glucocorticoid increase in mice
Hori T et al. (2017): Configuration-dependent variability of the effect of an electric field on the plasma glucocorticoid level in immobilized mice

Exposed system:

animal
mouse/BALB/c
whole body

Methods Endpoint/measurement parameters/methodology

effects on blood parameters (white blood cell count, red blood cell count, haemoglobin levels and haematocrit; automatic analyser) and glucocorticoid level in plasma (spectrophotometry)
body mass

Investigated system:

isolated bio./chem. substance
blood samples

Time of investigation:

after exposure

Main outcome of study (acc. to author)

Plasma glucocorticoid levels were significantly decreased in all immobilization and electric field exposure groups (groups 1a-1f) compared to immobilization alone (groups 3a-f).
Electric field exposure had no significant effects on the other blood parameters.
The authors conclude that exposure to a 50 Hz electric field might decrease immobilization-induced stress in mice regardless of age and sex.

Study character:

medical/biological study
experimental study
full/main study

Study funded by

not stated/no funding

Harakawa S et al. (2020): Extremely low-frequency electric field suppresses not only induced stress response but also stress-related tissue damage in mice
Hori T et al. (2018): Characterization of the suppressive effects of extremely-low-frequency electric fields on a stress-induced increase in the plasma glucocorticoid level in mice
Di G et al. (2018): A comparative study on effects of static electric field and power frequency electric field on hematology in mice
Harakawa S et al. (2017): Time-dependent changes in the suppressive effect of electric field exposure on immobilization-induced plasma glucocorticoid increase in mice
Hori T et al. (2017): Configuration-dependent variability of the effect of an electric field on the plasma glucocorticoid level in immobilized mice
Hori T et al. (2015): Exposure to 50 Hz electric fields reduces stress-induced glucocorticoid levels in BALB/c mice in a kV/m- and duration-dependent manner
Szemerszky R et al. (2010): Stress-related endocrinological and psychopathological effects of short- and long-term 50Hz electromagnetic field exposure in rats
Harakawa S et al. (2004): Effect of a 50 Hz electric field on plasma ACTH, glucose, lactate, and pyruvate levels in stressed rats
de Bruyn L et al. (1994): Electric field exposure and evidence of stress in mice
Quinlan WJ et al. (1985): Neuroendocrine parameters in the rat exposed to 60-Hz electric fields
Hackman RM et al. (1981): Corticosterone levels in mice exposed to high-intensity electric fields
Free MJ et al. (1981): Endocrinological effects of strong 60-Hz electric fields on rats
Marino AA et al. (1977): In vivo bioelectrochemical changes associated with exposure to extremely low frequency electric fields