Effect of MnTBAP on sperm ultra-rapid freezing and its proteomics study

Effects of MnTBAP on Porcine Semen Cryopreservation and Capacitation

Antioxidants protect cellular function and structure by neutralizing the oxidative stress caused by increased reactive oxygen species (ROS) during sperm freezing. Studies on cryopreservation using various antioxidants have demonstrated encouraging results. Many studies have used antioxidants to increase the efficiency of sperm freezing and to improve the success rate of artificial insemination and pregnancy. Manganese (III) tetrakis (4-benzoic acid) porphyrin chloride (MnTBAP) is a newly synthesized antioxidant with positive effects on sperm morphology and capacitation in humans, rams, and stallions. In this study, porcine semen was treated with 0, 50, 100, and 150 μM of MnTBAP based on a Tris-egg-yolk extender and frozen to determine whether MnTBAP can assist the status of sperm during cryopreservation. First, motility was assessed using the computer-assisted sperm analysis (CASA) system, with the 100 μM treatment group showing the highest motile rate (66.8%) compared with that of the other groups (control, 51.1%; 50 μM and 150 μM, 59.6%); therefore, the remaining analyses were conducted comparing the two groups (control vs. 100 μM group; p < 0.01). Second, fluorescence staining was applied to examine the control and 100 μM groups using fluorescence microscopy. The viability (41.7% vs. 62.4%) and the acrosome integrity (77.9% vs. 86.4%) differed significantly (p < 0.05). In addition, the mitochondrial membrane potential (MMP) was 46.5% vs. 51.9%; the fragmentation rate, estimated using the Sperm-sus-Halomax kit, was 63.4% vs. 57.4%; and the detected caspase activity was 30.1% vs. 22.9%. These tended to be higher in the treated group but did not differ significantly. Third, measurements using FACSLyric revealed that the 100 μM treatment group exhibited a state of elevated normal lipid arrangement within the plasma membrane and diminished levels of apoptosis and ROS (p < 0.01). We assessed the expression of genes relevant to antioxidant effectiveness using real-time RT-qPCR. Our findings indicated significant alterations in the expression levels of various mRNA species, with the exception of NOX5 (p < 0.05). Finally, the straws were dissolved and used to treat matured denuded oocytes to investigate the effect on fertilization and embryo development in vitro. The cleavage rate was (77.6% vs. 84.1%), and the blastocyst rate was 9.7% vs. 11.4% (p < 0.05). In conclusion, these results suggest that MnTBAP positively affected sperm freeze-thawing, improving the fertilization capacity, and leading to increased embryo development.

The effect of the mitochondria-targeted antioxidant Mito-tempo during sperm ultra-rapid freezing

During the freeze-thaw process, human spermatozoa are susceptible to oxidative stress, which may cause cryodamage and reduce sperm quality. As a novel mitochondria-targeted antioxidant, Mito-tempo has been used for sperm cryopreservation. However, it is currently unknown what role it will play in the process of sperm ultra-rapid freezing. The purpose of this study was to investigate whether Mito-tempo can improve sperm quality during ultra-rapid freezing. In this study, samples with the addition of Mito-tempo (0, 5, 10, 20, and 40 μM) to sperm freezing medium were selected to evaluate the changes in sperm quality, antioxidant capacity and ultrastructure after ultra-rapid freezing. After ultra-rapid freezing, the quality and antioxidant function of the spermatozoa were significantly reduced and the spermatozoa ultrastructure was destroyed. The addition of 10 μM Mito-tempo significantly increased post thaw sperm motility, viability, plasma membrane integrity and mitochondrial membrane potential (P < 0.05). Moreover, the DNA fragmentation index (DFI), ROS levels and MDA content were reduced, and the antioxidant enzyme (CAT and SOD) activities were enhanced in the 10 μM Mito-tempo group (P < 0.05). Moreover, Mito-tempo protected sperm ultrastructure from damage. In conclusion, Mito-tempo improved the quality and antioxidant function of sperm after ultra-rapid freezing while reducing freezing-induced ultrastructural damage.

Effects of resveratrol on DLD and NDUFB9 decrease in frozen semen of Mongolian sheep

Mongolian sheep are a breed of sheep in China known for their excellent cold and drought resistance. Sperm from Mongolian sheep are often cryopreserved to improve breeding outcomes. However, cryopreservation of sperm often results in issues such as reduced vitality and altered morphology. Therefore, the objective of this study was to investigate the impact of the cryoprotectant resveratrol on frozen sperm from Mongolian sheep, specifically examining its effects on key proteins during cryopreservation. In this study, sperm samples were obtained from three adult Mongolian rams and processed through semen centrifugation. The sperm motility parameters of Fresh Sperm Group (FR), Resveratrol added before freezing group (FF-Res), Resveratrol-free frozen sperm group (FT), and Resveratrol added after freeze-thawing group (FA-Res) were determined. The tandem mass tags (TMT) peptide labeling combined with LC-MS/MS was used for proteomic analysis of the total proteins in FR and FT groups. A total of 2651 proteins were identified, among which 41 proteins were upregulated and 48 proteins were downregulated after freezing. In-depth bioinformatics analysis of differentially abundant proteins (DAPs) revealed their close association with the tricarboxylic acid cycle (TCA) and oxidative phosphorylation pathway. The energy-related protein dihydrolipoamide dehydrogenase (DLD) and the reactive oxygen species (ROS)-related protein NADH dehydrogenase 1 beta subcomplex subunit 9 (NDUFB9) exhibited significant decreases, indicating their potential role as key proteins contributing to reduced sperm vitality. The study demonstrated that the addition of resveratrol (RES) to semen could elevate the expression levels of DLD and NDUFB9 proteins. This study represents the pioneering proteomic analysis of Mongolian ram sperm before and after cryopreservation, establishing the significance of DLD and NDUFB9 as key proteins influencing the decline in vitality following cryopreservation of Mongolian ram sperm. These findings clarify that resveratrol can enhance the levels of DLD and NDUFB9 proteins in cryopreserved Mongolian ram sperm, consequently enhancing their vitality.