Antagonistic effects of selenium on lead-induced oxidative stress and apoptosis of Leydig cells in sheep

The objective of this study was to investigate the antagonistic effects of selenium (Se) on lead (Pb)-induced oxidative stress and apoptosis of sheep Leydig cells and its underlying mechanism. Leydig cells collected from 8-month-old sheep were treated with Pb (40 μmol/L) and/or Se (2 μmol/L), respectively. CCK-8 assay was used to detect cell proliferation and apoptosis after cultured for 48 h. The abundances of pro-apoptosis (BAX, CASPASE 3 and CASPASE 8) and NRF2-related (NRF2, HO-1, NQO1 and γ-GCS) genes were detected by real-time PCR and western blot analysis, respectively. The results showed that the highest cell viability was observed in the Se group. Compared with the control group, Pb treatment led to the higher ROS level and greater abundances of BAX, CASPASE 3 and CASPASE 8 mRNA transcripts. Treatment with Pb + Se resulted in an increased (P < 0.05) abundances of NRF2, HO-1, NQO1 and γ-GCS mRNA transcripts and proteins. Compared with the Pb group, the Se + Pb treatment dramatically decreased (P < 0.05) the ROS level and relative abundances of pro-apoptosis genes. The greater (P < 0.05) abundances of pro-apoptosis and NRF2-related mRNA transcripts and proteins were also obtained in the Se + Pb group. The abundances of BAX, CASPASE 3 and CASPASE 8 genes in the SeML₃₈₅ group were greater (P < 0.05) than in the Se group. Compared with the corresponding groups without ML385, treatment with ML385 decreased (P < 0.05) cell viability and the relative abundances of pro-apoptosis and NRF2-related genes. These results indicate that Pb-induced oxidative stress can inhibit the viability of Leydig cells by modulating pro-apoptosis gene expression. NRF2 pathway could be involved in the antagonistic effect of Se on Pb-induced apoptosis of Leydig cells in sheep. This study is expected to provide some experimental evidences for Se treatment of Pb-induced reproductive disorders.