Finnie JW, Cai Z, Manavis J, Helps S, Blumbergs PC. (2010). Microglial activation as a measure of stress in mouse brains exposed acutely (60 minutes) and long-term (2 years) to mobile telephone radiofrequency fields. Pathology. 42(2):151-154.
Microglia form a network in the brain that responds to any change in the microenvironment, and their activation may occur without obvious neuropathological alterations. Microglia express ionized calcium binding adaptor molecule (Iba1), the protein that is up-regulated during microglial activation.
The objective of the study was to determine whether acute (60 minutes) or long-term (2 years) exposure of the brain to radiofrequency field (RF) emitted from mobile phones produces microglial activation using Iba1 immunostaining.
Mice received whole-body 900 MHz RF exposure at SAR 4 W/kg for 60 minutes or for 104 weeks (5 days per week). There were two control groups: sham-exposed group and non-exposed freely moving cage group to control for stress-related effect of confinement during exposure. A total of 10 animals per group were used. Brains subjected to a stab wound were used as a positive control. Iba1 immunohistochemistry was performed on the cingulate cortex and hippocampus areas of the brain. Two pathologists unaware of the treatment group independently examined the brain sections.
The pathologists did not find differences in microglial expression between the exposed, sham-exposed and freely-moving controls after either short or long-term exposure. This finding was confirmed by quantitative analyses which showed no significant group differences in microglial cell body density or total Iba1 immunopositivity in the examined brain regions after short or long-term exposure. Substantial microglial activation was observed in the positive controls.
Interpretation and Conclusion
These results are consistent with the results from a study using the immediate early gene c-fos as a marker of neural stress after short and long-term exposure to RF fields. In conclusion, acute or long-term exposure of murine brains to mobile phone RF fields did not produce microglial activation detectable by Iba1 immunostaining.