To study whether glucocorticoids take part in cognition impairment after exposure to chronic low-power-density microwave fields.
56 rats were divided into four groups (each group = 14 rats): 1) exposure group, 2) exposure + RU486 treatment, 3) exposure + saline solution treatment, and 4) sham exposure group. 30 minutes before the first exposure, rats were subcutaneously injected with either the glucocorticoid receptor antagonist RU486 (120 mg/kg) or physiological saline. Rats were then given repeated injections every fifth day.
Four animals of each group were used for apoptosis investigation, five animals were used for behavioural tests, and five animals were used for corticosterone level determination.
| Exposure | Parameters |
|---|---|
|
Exposure 1:
2.45 GHz
Modulation type:
pulsed
Exposure duration:
continuous for 3 hr/day for up to 30 days
|
|
animals were divided into four groups: i) MW exposure ii) MW exposure + 120 mg/kg RU486 iii) MW exposure + 1 ml/kg physiological saline iv) sham exposure
| Frequency | 2.45 GHz |
|---|---|
| Type | |
| Exposure duration | continuous for 3 hr/day for up to 30 days |
| Modulation type | pulsed |
|---|---|
| Pulse width | 10 µs |
| Packets per second | 800 |
| Exposure source | |
|---|---|
| Setup | cylindrical waveguide system where individual cylindrical exposure tubes are connected through a power divider network to the single MW source; each tube comprises a section of the circular waveguide constructed of galvanized wire screen in which a circularly polarized TE11-mode field configuration is excited; the tube contains a 23.6 cm long plastic chamber with a diameter of 17.6 cm |
| Sham exposure | A sham exposure was conducted. |
| Measurand | Value | Type | Method | Mass | Remarks |
|---|---|---|---|---|---|
| power density | 1 mW/cm² | spatial average | - | - | - |
| SAR | 0.2 W/kg | average over time | measured | whole body | - |
| SAR | 0.7 W/kg | average over time | calculated | brain | - |
The data showed that microwave exposed rats had significant deficits in spatial learning and memory performance. The data analysis showed that microwave exposure induced a significant prolongation in escape latency on the fourth, fifth and sixth day and goal quadrant dwell-time on day seven was significantly reduced in microwave exposed rats.
Microwave exposure increased levels of plasma corticosterone, glucocorticoid receptor nuclear translocation (microwave exposure caused a decrease in the cytoplasmic signal and an increase in the nuclear signal compared to sham exposed control) and apoptosis in the hippocampus.
However, co-exposure of the glucocorticoid receptor antagonist RU486 with microwave exposure partially reversed the cognitive impairment and neuronal changes.
These findings indicate that glucocorticoid receptors might contribute to the cognition deficit induced by chronic low-power-density microwave exposure.
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