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Medical/biological Study (experimental study)

Elevation of plasma corticosterone levels and hippocampal glucocorticoid receptor translocation in rats: a potential mechanism for cognition impairment following chronic low-power-density microwave exposure. med./biol.

PubMed Entry

Journal web site

Aim of study (according to author)
To study whether glucocorticoids take part in cognition impairment after exposure to chronic low-power-density microwave fields.
Background/further details:
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.

Endpoints

• effects on the neurological system: plasma corticosterone level, hippocampal glucocorticoid receptor translocation and apoptosis
• cognitive/behavioural endpoints: spatial learning and memory

Exposure
General category: low level microwaves, PW (pulsed wave), 2.45 GHz

Field characteristics	Parameters
2.45 GHz pulsed (PW) exposure duration: continuous for 3 hr/day for up to 30 days	power flux density: 1 mW/cm² spatial average SAR: 0.2 W/kg average over time (whole body) SAR: 0.7 W/kg average over time (brain)

Exposed system:
animal (species/strain): rat/Wistar
whole body exposure

Methods
Endpoint/Measurement parameters/Methodology

• effects on the neurological system: plasma corticosterone level (radioimmunoassay), hippocampal glucocorticoid receptor protein expression (in cytoplasmic and nuclear fractions; Western blot), hippocampal apoptosis (TUNEL assay)
• cognitive/behavioural endpoints: spatial learning and memory (Morris water maze: escape latency and goal quadrant dwell-time in the probe trial; duration of training: 6 days; probe trial on day seven)

Main outcome of study (according to author)
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.

(Study character: medical/biological study, experimental study, full/main study, blind study)

Study funded by

• National Natural Science Foundation (NSFC), China
• Chendgu Medical College, China
• Science and Technology Bureau of Sichuan Province, China

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