Endocrine Abstracts

Background: As a trace element selenium (Se) is essential for man and animals, in particular for the maintenance of spermatogenesis and male fertility. A growing number of evidence shows that Se is necessary for testosterone synthesis, and inappropriate concentration, Se can stimulate Leydig cell proliferation. However, Se can also act as a metalloestrogen, which can mimic estrogen and activate the estrogen receptors. In higher concentrations, Se might have an adverse effect on male fertility.

Objectives: The aim of this study was to investigate the effect of selenium on the epigenetic status of mouse Leydig cells.

Methods: Mouse Leydig cells (MA-10) were treated for 24h with sodium selenite (Na2SeO3) in 4 μM and 8 μM concentrations. Immunofluorescence was utilized for the detection of γH2AX and 5-methylocytosine. Western blot was employed to analyze the expression of γH2AX. qRT-PCR was used to evaluate the expression of methyltransferases (Dnmt1, Dnmt3a, Dnmt3b).

Results: Independently of the dose, treatment did not affect the morphology of the cells. However, we found an increase in the number of lipid droplets between treated cells. Immunofluorescence revealed strong immunosignal for 5-methylcytosine in both control and treated cells, with a stronger signal in the 8 μM treated group. qRT-PCR confirmed an increased expression of Dnmt3b in 8 μM cells. Analysis of expression of γH2AX (a marker for double-stranded DNA breaks) revealed an increased amount of DNA brakes in the group treated with 8 μM concentration.

Conclusions: High concentration of Se causes DNA breaks and changes in Leydig cell methylation status, especially in the case of de novo methylation which is mediated by Dnmt3b. This might be an adaptive mechanism of cells in response to the changes in the microenvironment.