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.
|Exposure duration||continuous for 3 h/day on 30 days|
|Pulse width||10 µs|
|Packets per second||800|
|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.|
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.