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.
|Exposure duration||60 minutes|
|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|
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.|
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.