The Dilayed Effects Of Pulsed Microwave On The Central Nervous System Of Mice

[Objectives] Several epidemiological studies reported the relationship between electromagnetic fields (EMF) exposure and the development of Alzheimer's disease. We suppose that EMF exposure might have delayed effects on central nervous system. The present study attempted to verify our hypothesis.[Materials and methods] Male 2-month-old KM mice were exposed in the far field in an anechoic chamber to pulsed, H polarized 9-GHz microwaves (pulse repetition rate 2700, pulse width 0.25 microseconds, peak power density 12.89 W/ cm2) at an average incident power density of 8.1 mW/cm2 (average whole body specific absorption rate approximately 2.4 W/kg) for 20 minutes. The control group were sham-exposed. Astrocytes, microglia, capillary and A 3 were visualized using immunohistochemistry for glial fibrillary acidic protein (GFAP), ferritin, lectin BS-I-B4, 4G8, respectively, and permeability of the blood brain barrier(BBB) was determined using goat anti mouse IgG The spatial memory was tested in Morris water-maze.[Results](1): The behavioral tests showed that the exposed mice had poor spatial memory than sham-exposed mice 9 months later after exposure.(2): 3 days after exposure the results showed increasing of GFAP-positive astrocytes compared to sham-irradiated mice. There were some activated microglias in hippocampus. In hippocampus, basal ganglia, basal forebrain, temporal and frontal cortex, capillary proliferated, and the proliferation ofcapillary continued to 1 month later. 9 months later, irradiated mice showed more serious increasing and activity of astrocyte and microglia. Remarkably hypertrophyic astrocytes with long processes were found, and small blood vessels were stained deeply. In temporal cortex asrocytes tended to group in clusters with the processes oriented similarly. And in some area IgG IHC positive showed BBB broke down.(3): 9 months later after exposure, there were Aβ -positive plaques in the exposed mice.(4): 9 months later after exposure, liver cancer, mucosa-associated lymphoid tissue, acoustic neuroma, chronic inflammation and weight loss were found in exposed group.[Conclusions] These results strengthen our hypothesis that pulsed microwave exposure has delayed effects on CNS, or accelerates brain aging, and maybe, induced AD pathogenesis.