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Medical/biological study (experimental study)

Glucose administration attenuates spatial memory deficits induced by chronic low-power-density microwave exposure.

Published in: Physiol Behav 2012; 106 (5): 631-637

Aim of study (acc. to author)

To investigate whether glucose treatment attenuated memory deficity caused by chronic low-power microwave exposure and the effect of microwave exposure on hippocampal glucose uptake.
Background/further details: Three experiments were performed:
1.) The levels of blood glucose and insulin and hippocampal glucose uptake were examined in three groups: 1a) exposed, 1b) sham exposed and 1c) cage control.
2.) The Morris water maze was conducted with five groups: 2 a) exposed, 2 b) exposed plus glucose injection 30 minutes before the daily training session, 2 c) exposed plus saline injection 30 minutes before the daily training session, 2 d) sham exposed and 2 e) cage control.
3.) The radial arm maze task was also conducted with five groups: 3 a) exposed, 3 b) exposed plus glucose injection 30 minutes before the daily training session, 3 c) exposed plus saline injection 30 minutes before the daily training session, 3 d) sham exposed and 3 e) cage control (The radial arm maze is used to test spatial memory, a maze consisting of eight arms with food at the end of each arm and all radiating from a small circular central platform; counted is the number of reentries into an arm already visited).
Each group consisted of 6 adult male rats.

Endpoint

Exposure

Exposure Parameters
Exposure 1: 2.45 GHz
Modulation type: pulsed
Exposure duration: continuous for 3 h/day on 30 days
  • power 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)
General information
Some groups of the rats were treated with 100 mg/ml glucose at a dose of 100 mg/kg 30 min before the daily training session.
Exposure 1
Main characteristics
Frequency 2.45 GHz
Type
Polarization
  • circular
Exposure duration continuous for 3 h/day on 30 days
Modulation
Modulation type pulsed
Pulse width 10 µs
Packets per second 800
Exposure setup
Exposure source
Setup circular waveguide constructed of galvanized wire screen in which a circulary polarized TE11-mode field configuration was excited; 23.6 cm long cylindrical transparent plastic chamber with a diameter of 17.6 cm and a floor width of 14.5 cm was located in the middle of the wave guide; single rat placed inside the plastic chamber
Sham exposure A sham exposure was conducted.
Parameters
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 measured brain -
Reference articles
  • Li M et al. (2008): 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.
  • Chou CK et al. (1992): Long-term, low-level microwave irradiation of rats.
  • McRee DI et al. (1984): Whole-body and local dosimetry in rats exposed to 2.45-GHz microwave radiation.
Exposed system:

Methods Endpoint/measurement parameters/methodology

Investigated material:
Investigated organ system:
Time of investigation:
  • after exposure

Main outcome of study (acc. to author)

The blood glucose and insulin levels were not affected by chronic microwave exposure, but the glucose uptake decreased in hippocampal slices of exposed rats compared to sham exposed rats. This effect was also observed in the presence of insulin.
Regarding the Morris water maze task, a significant prolongation in latency time occured during the training sessions and the time, spent in the target quadrant, was significantly reduced in the probe trail in exposed groups compared to sham exposed groups. The latency of the glucose-treated group was significantly reduced compared with the saline-treated group. In the probe trial, the glucose-treated rats spent a longer time in the target quadrant as compared with the saline treated group.
In the radial arm maze task, the errors in the exposed group were significantly increased compared to the sham exposed group. The errors in the glucose-treated group were significantly reduced compared with the saline-treated group.
The authors conclude that this study demonstrated that the hippocampus-dependent spatial learning and memory of rats could be impaired by chronic microwave exposure and that glucose administration attenuated these deficits.
Study character:

Study funded by

  • National Natural Science Foundation (NSFC), China
  • Program 973, China

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