Morphophysiological status of rat thyroid gland after subchronic exposure to low frequency electromagnetic field

The objective of this study was to examine the impact of low-frequency electromagnetic field on male rat thyroid gland of Mill Hill strain. Animals were exposed to 50 Hz frequency, of decaying intensity from 500 microT to 50 microT and 10 V/m field, beginning 24 hours after birth, 7 hours a day, 5 days a week during three months. Results of histological and stereological analysis showed increased volume density of thyroid follicles, decreased thickness of the follicular epithelium, intrafollicular colloid content in lumen, decreased thyroid activation index, increased volume density of parafollicular cells, decreased volume of interfollicular connective tissue and increased number of degranulated mast cells in exposed animals in regard to control animals. Radioimmunologic assays were used to examine thyroid hormone concentrations in the blood serum revealing decrease of the total T4 as well as of total T3 in animals exposed to electromagnetic field in regard to controls. The obtained results show that a three month-exposition of animals to low frequency electromagnetic field led to morphofunctional alterations of the thyroid gland that can be referred to as reduced activity of the gland.