Lycopene and SKQ1 Improve Boar Sperm Quality During 17 °C Storage via the AMPK/Nrf2 Pathway.

During the storage of boar sperm at 17 °C, reactive oxygen species (ROS) are continuously generated. Excessive ROS can disrupt the mitochondrial redox balance and cause sperm damage. In this study, boar semen was diluted with solutions containing different concentrations of the natural antioxidant lycopene (1, 5, 10, 20, 40, 80 μM) or the mitochondria-targeted antioxidant SKQ1 (1, 5, 10, 25, 50, 70 nM), and sperm vitality was assessed throughout storage at 17 °C. Based on the screening results, the optimal concentrations were selected for combined application to investigate their effects on sperm quality and potential synergistic interactions. The results demonstrated that sperm motility was significantly higher in the 20 μM lycopene and 50 nM SKQ1 treatment groups compared to the control (p < 0.05). The combined treatment of 20 μM lycopene and 25 nM SKQ1 exhibited a synergistic effect, significantly improving sperm vitality, acrosome and membrane integrity, superoxide dismutase (SOD), glutathione peroxidase (GSP), adenosine triphosphate (ATP) levels (p < 0.05). Meanwhile, ROS and malondialdehyde (MDA) levels were significantly reduced (p < 0.05). Metabolomics analysis identified 52 differential metabolites (p < 0.05), including ABC transporters, corticosterone, and palmitic acid. KEGG pathway enrichment analysis revealed that these metabolites were mainly associated with steroid hormone biosynthesis, ABC transporters, and AMPK signaling pathways (p < 0.05), most of which were related to sperm cell energy metabolism and signal transduction. Furthermore, treatment with antioxidants significantly increased p-AMPK and Nrf2 expression in sperm cells (p < 0.05). These findings suggest that the combination of lycopene and SKQ1 improves boar sperm quality during 17 °C storage by enhancing energy metabolism and mitigating oxidative stress, potentially through the activation of the AMPK/Nrf2 pathway.