Antioxidant properties and transcriptome of cauda epididymis with different levels of fertility in Hu lambs.

Oxidative stress damages the structure of sperm and affects its fertility. Further maturation and storage of spermatozoa occur in the epididymis. Thus, a balanced environment between free-radical production and the antioxidant–enzyme system is important. This study aimed to investigate differences in antioxidative activity in epididymis between high and low fertility levels of Hu sheep. A total of 179 Hu ram lambs aged 56 days were fed up to 6 months in the same environment. After feeding trial, all rams were slaughtered. According to the epididymis weight, cauda sperm concentration, and histo-morphological observation, 18 individuals were selected and divided into low fertility (n = 9) and high fertility (n = 9) groups. The RNA sequencing results showed 1404 differentially expressed genes (DEGs), with 735 genes upregulated and 669 genes downregulated in the high fertility group compared with the low fertility group. Sixteen DEGs related to lipid metabolism and oxidative stress, including GPX3 , GPX5 , LRP1 , PLCB1 , CRISP2 , BSPH1 , and ACSBG1 , were screened by qPCR, and results were correlated well with the sequencing data. Antioxidative indices such as total antioxidant capacity (21.29 ± 5.97 vs. 30.23 ± 4.56 μM/gprot) and glutathione peroxidase (39.75 ± 7.61 vs. 68.84 ± 12.51 U/mgprot) increased in the high fertility group. However, the relative expression of mtDNA and malondialdehyde concentration (0.75 ± 0.15 vs. 0.54 ± 0.10 nmol/mgprot) and the reactive oxygen species (ROS) content significantly decreased (P < 0.05). Therefore, epididymis from high-fertility group had strong antioxidative activity and protected spermatozoa from ROS. [Display omitted] • The diameter of epididymal ducts was increased in epididymis with high fertility of Hu sheep. • RNA-Seq detected differences in epididymis cauda transcriptome. • There were 1404 differentially expressed genes between the high fertility and low fertility groups. • The genes affecting lipid metabolism and sperm maturation were screened out. • Epididymis from high fertility group had strong antioxidative activity, protecting spermatozoa from reactive oxygen species. [ABSTRACT FROM AUTHOR]