Rat Thymocyte Apoptosis and Proliferation Variations in Chronic Exposure to Low-Dose Dichlorodiphenyltrichloroethane

The aim of the investigation was to study apoptosis and proliferation of rat thymocytes when exposed to low-dose dichlorodiphenyltrichloroethane (DDT) provided for by its maximum allowable level in food products.

Materials and Methods. The experiment was carried out on 64 Wistar male rats administered DDT at doses of 1.890±0.086 and 7.77±0.17 µg/kg/day within 6 and 10 weeks. We performed a histological study of thymus preparations, immunohistochemistry of pro-apoptotic proteins Bax and p53, the assessment of the proliferative activity of thymocytes by a radionuclide method, and the corticosterone and interleukin-2 concentrations in rat blood serum using an enzyme immunoassay.

Results. The study of thymus of control and experimental rats 6 weeks after the experiment start showed the selected doses of DDT to activate the synthesis of pro-apoptotic proteins and initiate p53-dependent apoptosis of both low- and high-grade differentiated thymocytes resulting in focal depletion of thymic cortex. It causes a reactive increase of interleukin-2 production and thymocyte proliferation, however, results in no thymocyte population recovery. Subsequently, with DDT accumulation and exposure time increase, there is the enhanced death of both lymphocytes and reticular epithelial cells, and proliferative activity of thymocytes is suppressed despite the decreased secretion of glucocorticosteroids by adrenals, it being the basic acceleration mechanism of observable involutory changes of thymus.

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Yaglova N.V., Yaglov V.V., Timokhina Е.P., Nazimova S.V., Obernikhin S.S. Rat Thymocyte Apoptosis and Proliferation Variations in Chronic Exposure to Low-Dose Dichlorodiphenyltrichloroethane. Sovremennye tehnologii v medicine 2017; 9(1): 62, https://doi.org/10.17691/stm2017.9.1.07