Effects of Benzo (a) Pyrene and 2,2,4,4-Tetrabromodiphenyl Ether Exposure on the Thyroid Gland in Rats by Attenuated Total Reflection Fourier-Transform Infrared Spectroscopy

Benzo-[a]-pyrene (B-[a]-P) and 2,2 ',4,4 '-tetrabromodiphenyl ether (BDE-47) are widespread environmental pollutants and can destroy thyroid function. We assessed the biochemical changes in the thyroid tissue of rats exposed to B-[a]P and BDE-47 using attenuated total reflection Fourier-transform infrared spectroscopy combined with support vector machine-(SVM). After B-[a]P and BDE-47 treatment in rats, the structure of thyroid follicles was destroyed and epithelial cells were necrotic, indicating that B-[a]P and BDE-47 may lead to changes of the thyroid morphology of the rats. These damages are mainly related to C= O stretch vibrations of lipids (1743 cm(-1)), as well as the secondary structure of proteins [amide I (1645 cm(-1)) and amide II (1550 cm(-1))], and carbohydrates [C-OH (1138 cm(-1)), C-O (1106 cm(-1), 1049 cm(-1), 991 cm(-1)), C-C (1106 cm(-1)) stretching] and collagen (phosphodiester stretching at 922 cm(-1)) vibration modes. When SVM was used for classification, there was a substantial separation between the control and the exposure groups (accuracy = 96%; sensitivity = 98%; specificity = 87%), and there was also a major separation between the exposed groups (accuracy = 93%; sensitivity = 94%; and specificity = 92%).