Experimental analysis of HSP 90 and 70 in-vivo changes induced in the thyroid by exposure to microwave electromagnetic fields

Non-ionizing radiation at 2.45 GHz may modify the expression of genes that codify heat shock proteins (HSP) in the thyroid gland. Using the Enzyme-Linked ImmunoSorbent Assay (ELISA) technique, we studied levels of HSP-90 and HSP-70. We also used hematoxilin eosin to look for evidence of lesions in the gland and applied the DAPI technique of fluorescence to search for evidence of chromatin condensation and nuclear fragmentation in the thyroid cells of adult female Sprague-Dawley rats. Fifty-four rats were individually exposed for 30 min to 2.45 GHz radiation in a Gigahertz Transverse Electromagnetic (GTEM) cell at different levels of non-thermal SAR, which was calculated using the FDTD technique. Ninety minutes after radiation, HSP-90 and HSP-70 had decreased significantly (p<0.01) after applying a SAR of 0.046±1.10 or 0.104±5.10
⁻³
W/kg. Twenty-four hours after radiation, HSP-90 had partially recovered and HSP-70 had recovered completely. There are few indications of lesions in the glandular structure and signs of apoptosis were negative in all radiated animals. The results suggest that acute sub-thermal radiation at 2.45 GHz may alter levels of cellular stress in rat thyroid gland without initially altering their anti-apoptotic capacity.