Endocrine Abstracts

More than twenty years after Chernobyl nuclear power plant explosion, radionuclides are still mainly bound to the organic soil layers. Currently, the radiation exposure is dominated by the internal exposure to gamma-radiation following the decay of ¹³⁷Cs, due to presence of ¹³⁷Cs into the food chain. Because of this persistence of contamination with ¹³⁷Cs, questions regarding public health for people living in contaminated areas were raised. Several studies report an increase number of various malfunctions affecting the cardiovascular, nervous and immune systems, in addition to a large increase of thyroid cancers. Moreover, it has been shown that ¹³⁷Cs accumulate in different organs such as the endocrine glands, the heart and the spleen.

Up to now the effects of the radionuclides such as ¹³⁷Cs have been poorly investigated on the testicular or adrenal steroidogenesis. Studies on ‘liquidators’ show some modifications of sperm parameters, along with perturbations within the levels of cortisol, ACTH, and testosterone have been observed following ¹³⁷Cs irradiation, but the effects of chronic internal contamination has not been studied yet.

We investigated the biological effects of chronic exposure to ¹³⁷Cs on testicular and adrenal steroidogenesis metabolisms in rat. Animals were exposed to radionuclide in their drinking water for 9 months at a dose of 6500 Bq/l (610 Bq/kg per day), a dose that can be found in contaminated areas near Chernobyl.

Cesium 137 contamination decreases the level of circulating 17β-estradiol, and increases corticosterone level. In testis, several nuclear receptors messenger expression is disrupted; levels of mRNA encoding LXRα alpha and LXR beta are increased, whereas FXR mRNA presents a lower level. Adrenal metabolism presents a paradoxical decrease in cyp11a1 gene expression. In conclusion, our results show for the first time molecular and hormonal modifications in testicular and adrenal steroidogenic metabolism, induced by chronic contamination with low doses of ¹³⁷Cs.