title: Exposure to non-ionizing radiation provokes changes in rat thyroid morphology and expression of HSP-90.
abstract: Non-ionizing radiation at 2.45 GHz may modify the morphology and expression of genes that codify heat shock proteins (HSP) in the thyroid gland. Diathermy is the therapeutic application of non-ionizing radiation to humans for its beneficial effects in rheumatological and musculo-skeletal pain processes. We used a diathermy model on laboratory rats subjected to maximum exposure in the left front leg, in order to study the effects of radiation on the nearby thyroid tissue. Fifty-six rats were individually exposed once or repeatedly (10 times in two weeks) for 30 min to 2.45 GHz radiation in a commercial chamber at different non-thermal specific absorption rates (SARs), which were calculated using the finite difference time domain technique. We used immunohistochemistry methods to study the expression of HSP-90 and morphological changes in thyroid gland tissues. Ninety minutes after radiation with the highest SAR, the central and peripheral follicles presented increased size and the thickness of the peripheral septa had decreased. Twenty-four hours after radiation, only peripheral follicles radiated at 12 W were found to be smaller. Peripheral follicles increased in size with repeated exposure at 3 W power. Morphological changes in the thyroid tissue may indicate a glandular response to acute or repeated stress from radiation in the hypothalamic-pituitary-thyroid axis. Further research is needed to determine if the effect of this physical agent over time may cause disease in the human thyroid gland.
authors: Morphological Sciences Department, University of Santiago de Compostela, 15782 Santiago de Compostela, Spain.
authors: Maria J
authors: MJ
authors: Misa-Agustiño
authors: Morphological Sciences Department, University of Santiago de Compostela, 15782 Santiago de Compostela, Spain.
authors: Teresa
authors: T
authors: Jorge-Mora
authors: Morphological Sciences Department, University of Santiago de Compostela, 15782 Santiago de Compostela, Spain.
authors: Francisco J
authors: FJ
authors: Jorge-Barreiro
authors: Morphological Sciences Department, University of Santiago de Compostela, 15782 Santiago de Compostela, Spain.
authors: Juan
authors: J
authors: Suarez-Quintanilla
authors: Applied Physics Department, University of Santiago de Compostela, 15782 Santiago de Compostela, Spain.
authors: Eduardo
authors: E
authors: Moreno-Piquero
authors: Applied Physics Department, University of Santiago de Compostela, 15782 Santiago de Compostela, Spain.
authors: Francisco J
authors: FJ
authors: Ares-Pena
authors: Morphological Sciences Department, University of Santiago de Compostela, 15782 Santiago de Compostela, Spain melena.lopez.martin@usc.es.
authors: Elena
authors: E
authors: López-Martín
mesh_terms: D000818:Animals; D015415:Biomarkers / Q000378:metabolism; D003972:Diathermy / Q000009:adverse effects; D005260:Female; D018841:HSP90 Heat-Shock Proteins / Q000378:metabolism*; D006801:Humans; D007150:Immunohistochemistry; D008872:Microwaves / Q000009:adverse effects*; D051381:Rats; D017207:Rats, Sprague-Dawley; D013961:Thyroid Gland / Q000378:metabolism / Q000473:pathology* / Q000528:radiation effects*; D013997:Time Factors; D014018:Tissue Distribution
chemical_list: D015415:Biomarkers; D018841:HSP90 Heat-Shock Proteins
keywords: Gigahertz; Thyroid; follicle; heat shock protein; septa; specific absorption rate
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