Ozguner F, Oktem F, Ayata A, Koyu A, et al. (2005)

The authors carried out their experiment on 4 groups of rats (10 in each group). The first was a control group that had no stress and no exposure to RFR. The second was a sham group that was placed in the exposure chamber, without the RFR. The third group of RFR-exposed animals was exposed at 900 MHz frequency for 30 minutes a day for 1 month. The SAR varied between 0.016 (whole body) and 4 W/kg (locally). (It is not clear where the local measurements were made). The fourth group consisted of animals that were exposed to the same RFR, but were also given caffeic acid phenethyl ester (CAPE), a natural flavonoid compound from the honey bee propolis. CAPE was given as an intraperitoneal injection before the daily exposure period.

At the end of 1 month the rats were sacrificed and the kidneys removed for examination of the levels of antioxidant levels - superoxide dismutase (SOD), catalase (CAT), and glutathione peroxidase (GSH-Px). The levels of the ROS nitric acid (NO) were also estimated, and of malondialdehyde (MDA), which is an index of lipid peroxidation. Finally, urinary N-acetyl-ß-D-glucosaminidase (NAG) was measured. NAG is a marker of renal tubular injury.

In the RFR group, there was a significant decrease in the activities of the three antioxidant enzymes in the kidney tissues of the RFR-exposed group, compared with the control group and the sham-exposed group. The levels of NAG, MDA, and NO significantly increased in the RFR-exposed group, in comparison with the control and sham groups. However, the CAPE treated animals had levels of antioxidant enzymes and of NO, MDA, and NAG that were significantly different from the RFR-exposed group and, with the exception of GSH-Px and MDA, were not different from the control group.

The authors conclude that the changes demonstrate the role of oxidative mechanisms in 900 MHz phone-induced damage, and that CAPE ameliorates this damage.