Cerium oxide nanoparticles improve the post-thaw quality and in-vivo fertility of Beetal buck spermatozoa

Abstract

The motility, health quality, and membrane disorders of spermatozoa are adversely affected during the process of semen cryopreservation due to the over-production of reactive oxygen species (ROS). Cerium oxide nanoparticles (CeO₂NPs) possess properties to scavenge ROS either by mimicking specific antioxidants or by enhancing the activities of antioxidant enzymes. Therefore, we aimed at evaluating the effects of adding the CeO₂NPs in the TRIS-citrate-yolk extender on in-vitro antioxidant enzyme activities, spermatozoa quality attributes, and in-vivo fertility of post-thaw Beetal buck spermatozoa. The CeO₂NPs were prepared and characterized (UV-spectrophotometry, FTIR, and XRD). Semen samples, collected from bucks (n = 5), were distributed into five aliquots and diluted in an extender containing increasing concentrations of nanoparticles (0 μg/ml, called the control group, 25 μg/mL, 50 μg/mL, 75 μg/mL, and 100 μg/mL). At post-thaw, spermatozoa were evaluated for the above-mentioned attributes and the pregnancy rate by inseminating Beetal does (n = 252). Results demonstrated that CeO₂NPs mitigated the detrimental effects of cryopreservation as ROS production and lipid peroxidation were lower (P < 0.001) in the 25, 50, and 75 μg/mL CeO₂NPs-added groups compared to the control and 100 μg/ml CeO₂NPs-added group. The addition of 25 μg/mL CeO₂NPs improved (P < 0.001) the activities of superoxide dismutase, catalase, and peroxidase and the concentration of reduced glutathione (P < 0.001) compared to the other groups. In terms of sperm kinematics and velocity parameters, the groups added with the 25 and 50 μg/mL CeO₂NPs exhibited higher total motility (P < 0.001), sperm progressive motility (P = 0.003), and rapid velocity (P < 0.001). The group added with the 50 μg/mL CeO₂NPs had the highest (P = 0.04) average path velocity. The groups added with the 25 and 50 μg/mL CeO₂NPs also exhibited higher plasma membrane integrity (P = 0.003), acrosomal integrity, and viability (P < 0.001) compared to the control group. The DNA integrity was also higher (P < 0.001) in all the CeO₂NPs-added groups. The pregnancy rate was higher (P = 0.003) in the 25 (51.92 %) and 50 μg/mL CeO₂NPs (58.33 %) groups compared to the other groups. Conclusively, our findings suggest that the inclusion of cerium oxide nanoparticles in the TRIS-citrate-yolk freezing extender can reduce the occurrence of cryopreservation-induced damages to Beetal's buck spermatozoa and ultimately enhance the pregnancy rate in does.

Keywords: Antioxidant; Artificial insemination; Beetal goat; Cryopreservation; Nanoceria; Semen quality.