Role of seminal MDA, ROS, and antioxidants in cryopreservation and their kinetics under the influence of ejaculatory abstinence in bovine semen

Effects of Different Diluents and Freezing Methods on Cryopreservation of Hu Ram Semen

The purpose of this study was to investigate the effects of different diluents and freezing methods on the quality of thawed sperm after cryopreservation and find an inexpensive and practical method for freezing Hu ram semen for use in inseminations under farm conditions. Ejaculates were collected from five Hu rams. In experiment I, ejaculates were diluted with eight different freezing diluents (basic diluents A, B, C, D, E, F, G, and H). After dilution and cooling, the samples were loaded into 0.25 mL straws and frozen using the liquid nitrogen fumigation method. In experiment II, diluent C was used as the basic diluent and the semen was frozen using liquid nitrogen fumigation and two program-controlled cooling methods. For analysis, frozen samples were evaluated in terms of motility parameters (total motility (TM), progressive motility (PM)), biokinetic characteristics (straight-line velocity (VSL), average path velocity (VAP), curvilinear velocity (VCL), amplitude of lateral head displacement (ALH), wobble movement coefficient (WOB), average motion degree (MAD)), reactive oxygen species (ROS) level, and membrane and acrosome integrity. In experiment I, diluent C had higher TM, PM, and acrosome and membrane integrity and lower ROS compared to other extenders (p < 0.05) except diluent A. Diluent C exhibited higher (p < 0.05) VCL, VAP, ALH, WOB, and MAD compared to diluents B, D, E, and F. In experiment II, TM and all biokinetic characteristics did not show significant differences (p > 0.05) amongst the three freezing methods. Liquid nitrogen fumigation resulted in higher (p < 0.05) PM, membrane integrity, acrosome integrity, and lower ROS level compared to the program. In conclusion, the thawed semen diluted with diluent C had higher quality compared to other diluents. The liquid nitrogen fumigation demonstrated superior semen cryopreservation effects compared to the program-controlled cooling method using diluent C.

Evaluation of sperm and hormonal assessments in Wagyu, Nellore, and Angus bulls

Wagyu bulls are known to have a highly exacerbated libido, as shown by the intense sexual interest of young calves. Therefore we believe that Wagyu male animals have specialized Sertoli and Leydig cells that are directly involved with the sexual precocity in this breed as mature bulls have a small scrotal circumference. This study aimed to evaluate whether there were differences in the hormone and sperm characteristics of Wagyu bulls compared with the same characteristics of subspecies Bos indicus and Bos taurus sires. Frozen-thawed semen from Wagyu, Nellore, and Angus sires were analyzed for sperm kinetics (computer-assisted sperm analysis), plasma membrane integrity, chromatin integrity, acrosome status, mitochondrial activity, lipid peroxidation and hormone [luteinizing hormone (LH) and testosterone] serum concentration. The results showed that Wagyu had lower total motility and an increased number of sperm with no motility when compared with Nellore and Angus bulls. Wagyu breed did not differ from those breeds when considering plasma and acrosome membranes integrity, mitochondrial potential, chromatin resistance, sperm lipid peroxidation or hormone (LH and testosterone) concentrations. We concluded that Wagyu sires had lower total motility when compared with Nellore and Angus bulls. Wagyu breed did not differ from these breeds when considering plasma and acrosome membranes integrity, mitochondrial potential, chromatin resistance, sperm lipid peroxidation, or hormone (LH and testosterone) concentrations.

Grape Seed Proanthocyanidins Improve the Quality of Fresh and Cryopreserved Semen in Bulls

Oxidative stress leads to a decrease in semen quality during semen cryopreservation and fresh semen production. Grape seed proanthocyanidins (GSPs) are endowed with well-recognized antioxidant, anti-inflammatory, anti-cancer, and anti-aging activities. Therefore, the objective of this experiment was to explore the effects of GSPs on the quality of fresh and cryopreserved semen to provide a basis for GSPs as a new dietary additive and semen diluent additive for males' reproduction. Fresh semen from three healthy bulls aged 3 to 5 years old were gathered and mixed with semen diluents dissolved with 0 µg/mL, 30 µg/mL, 40 µg/mL, 50 µg/mL, and 60 µg/mL GSPs respectively. The motility, physiological structures (acrosome integrity, membrane integrity, mitochondrial activity), and antioxidant capacity of frozen-thawed sperm were measured after storage in liquid nitrogen for 7 days (d). Bulls were fed with 20 mg/kg body weight (BW) GSPs in their diet for 60 days; the weight of the bull is about 600 kg. Then, the reproductive performance and antioxidant indexes of bulls were measured before and after feeding. The results demonstrated that GSPs supplementation significantly increased sperm motility, physiological structures, GSH-Px, and CAT enzyme activities and significantly decreased MDA content in sperm during semen cryopreservation. The optimal concentration of GSPs was 40 µg/mL (p < 0.05). After 20 mg/kg (body weight) GSP supplementation, sperm motility was significantly heightened (p < 0.05), the sperm deformity rate was significantly reduced (p < 0.05), and antioxidant enzyme activities (such as SOD, CAT, and GSH-Px) were significantly enhanced (p < 0.05), and the production of MDA was significantly suppressed (p < 0.05) in serum compared with that before feeding. In conclusion, these results reveal that a certain concentration of GSPs has a good protective effect on sperm damage caused by semen cryopreservation and the reproductive performance reduction caused by stress in bulls, which may be attributed to the antioxidant function of GSPs. In summary, GSPs are a useful cryoprotective adjuvant and dietary additive for bull sperm quality.

Sperm cryopreservation: current status and future developments

The cryopreservation of spermatozoa is an important reproductive technology for the preservation of fertility in man and animals. Since the serendipitous discovery of glycerol as an effective cryoprotectant in 1947, sperm cryopreservation has undergone many changes in terms of the freezing methods employed, the rates at which samples are frozen and thawed, and the media used to preserve sperm functionality and DNA integrity. An extensive literature survey has been conducted addressing the cryoprotectants employed for both animal and human semen and the freezing protocols utilised. The results indicate that glycerol remains the dominant cryoprotective agent, usually incorporated into a balanced salt solution containing energy substrates, buffers, osmolytes and protein in the form of human serum albumin (human) or skimmed milk (animal). Realisation that some of the damage observed in cryostored cells involves the generation of reactive oxygen species during the thawing process, has prompted many studies to assess the relative merits of incorporating antioxidants into the cryopreservation media. However, in the absence of systematic comparisons, there is currently no consensus as to which antioxidant combination might be the most effective. Utilising our fundamental understanding of cryodamage to optimise cryopreservation protocols for each species will be important in the future.

The freezability of Mediterranean buffalo sperm is associated with lysine succinylation and lipid metabolism

Semen cryopreservation is used for the propagation of variety among species and domestic breeding. Mitochondria are implicated in sperm freezability, and their proteins are prone to succinylation, but the relationship between sperm freezability and mitochondrial protein succinylation is unclear. In this study, six bulls were classified as having good or poor freezability ejaculates (GFE or PFE, each 3 bulls). The fresh sperm mitochondrial membrane potential (MMP) and pan succinylation level of the two groups were first detected. Then the lysine succinylome and fatty acid content of the two groups were analyzed using label-free LC-MS/MS and GC-MS/MS in multiple reaction monitoring (MRM) modes, respectively. The results indicated that the GFE sperm had significantly higher MMPs than the PFE group (p < 0.05). A total of 1393 succinylation sites corresponding to 426 proteins were assessed and 5 succinylated peptides of the GFE group were markedly upregulated, while 3 were significantly downregulated (FC > 2.0 - < 0.5 and p-value < 0.05) when compared to the PFE group. Forty-six succinylated proteins were identified to have consistent presence/absence expression. The upregulated succinylated proteins in the GFE sperm were enriched in lipid metabolic processes. A total of 31 fatty acids were further subjected to quantitative analysis of which 23 including arachidic (C20:0), linolenic (C18:3n3), and docosahexaenoic acids (C22:6n3) were decreased in GFE sperm when compared with PFE (p < 0.05). These results suggest that lysine succinylation can potentially influence the sperm freezability of Mediterranean buffaloes through mitochondrial lipid metabolism. This novel study provides our understanding of sperm succinylation and the molecular basis for the mechanism of sperm freezability.

Hydroxytyrosol and resveratrol improves kinetic and flow cytometric parameters of cryopreserved bull semen with low cryotolerance

There is considerable interest in breeding programs to "rescue" semen with poor post-thaw fertility from bulls known as "bad freezers". We hypothesized that there may be an interaction between the post-thaw recovery of sperm and the efficacy of antioxidant addition to extenders. The current study assesses the effects of antioxidant additives hydroxytyrosol (HT) and resveratrol (RSV) on the post-thaw semen parameters in two groups of bulls classified as either high or low cryotolerant (i.e., "good" and "bad" freezers). Semen samples were collected from 40 bulls and processed in the extenders containing different concentrations of HT (experiment 1; 0, 25 and 50 µM) and RSV (experiment 2; 0.0, 0.01, 0.1 and 1 mM). In experiment 1, bulls in the low cryotolerance group had a significant improvement in post-thaw recovery at 25 µM and 50 µM (P < 0.05). These improvements were observed in motility and several cellular parameters. However, post-thaw semen quality in the high cryotolerance group was not significantly affected by the HT addition. In experiment 2, although RSV did not have any positive impact in high cryotolerance group, post-thaw recovery in the low cryotolerance bulls was significantly improved in 0.1 mM RSV. Oxidative stress markers in either high or low cryotolerance groups were not significantly changed by RSV addition (P > 0.05). It can be concluded that addition of optimized concentrations of HT and RSV to the extender could be a strategy for improving the post-thaw semen, especially in bulls with high genetic merit but low initial cryotolerance.

Anti-Aging Effect and Mechanism of Proanthocyanidins Extracted from Sea buckthorn on Hydrogen Peroxide-Induced Aging Human Skin Fibroblasts

Oxidative stress is the leading cause of skin aging damage. Excessive accumulation of reactive oxygen species (ROS) in cells induced by hydrogen peroxide (H₂O₂) triggers a decrease in collagen synthesis and an increase in collagen degradation, which are biomarkers of skin aging. We evaluated the potential protective mechanism of Sea buckthorn proanthocyanidins (SBP) against the oxidative stress-induced skin aging process from multiple aspects. We treated human skin fibroblasts (HSFs) with 300 µmoL/L of H₂O₂ for 24 h, followed by 25, 50, and 100 µg/mL of SBP for 24 h. The results showed that SBP could enhance the activities of superoxide dismutase (SOD) and glutathione (GSH), effectively remove excess ROS, and significantly improve the changes in cell morphology and viability caused by excessive ROS in skin cells. In addition, SBP could promote the synthesis of Col I in aging HSFs through the TGF-β1/Smads pathway and inhibit the degradation of Col I by regulating the MMPs/TIMPs system, thereby maintaining the stability of the ECM structure to achieve anti-aging purposes. Finally, we studied the migration ability of SBP, and the results showed that 100 µg/mL of SBP was most conducive to the cell migration of senescent cells, laying a foundation for follow-up animal experiments. These results will increase the application value of SBP in the cosmetic and antioxidative functional food industries.

Relationships between Biomarkers of Oxidative Stress in Seminal Plasma and Sperm Motility in Bulls before and after Cryopreservation

This study aimed at evaluating the relationship between biomarkers of oxidative stress (OS) in seminal plasma and sperm motility in bulls before and after cryopreservation. Three ejaculates per bull were collected from 20 young bulls. Each ejaculate was analyzed for motility before and after cryopreservation (by CASA), and the SP concentration of Advanced Oxidation Protein Products (AOPP), thiols, and carbonyl groups (CT) were examined. Then, based on their motility, the ejaculates were grouped into: high motility fresh (HMF), low motility fresh (LMF), high motility thawed (HMT), and low motility thawed (LMT) groups. Higher AOPP and thiol concentrations on SP were related (p < 0.05) to the higher LIN and BCF and lower ALH of fresh semen. In addition, AOPP and thiols were significantly higher in HMF than LMF. As a confirmation of this, the Receiver Operating Characteristic (ROC) curve analysis showed that AOPP and thiol concentrations in SP were able to discriminate between HMF and LMF ejaculates (Area Under the Curve of 71.67% and 72.04%, respectively). These observations give an alternative perspective on the relationship between sperm motility and the OS parameters of SP, which need further investigations.

The protective effects of Clerodendranthus spicatus (Thunb.) C. Y. Wu extract on oxidative stress induced by 2,2'-azo (2-methylpropamidine) dihydrochloride in HL-1 mouse cardiomyocytes

To investigate the protective effects of Clerodendranthus spicatus (Thunb.) C. Y. Wu extract (CSTE) on oxidative stress injury in HL-1 mouse cardiomyocytes induced by 2,2'-azo (2-methylpropamidine) dihydrochloride (AAPH, 1 mmol/L), HL-1 cells were co-cultured with different concentrations (10–100 μg/mL) of the CSTE for 24 h. A cell damage model was established by continuously culturing the cells in Dulbecco's Modified Eagle Medium plus AAPH for 4 h. Cell survival rates were measured by the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl-2H-tetrazolium bromide assay, and by measuring intracellular malondialdehyde (MDA) content. MDA and total reactive oxygen species (ROS) levels were determined by thiobarbituric acid colorimetry and the 2',7'-dihydrodichlorofluorescent sodium yellow diacetate probe, respectively. Apoptosis was measured by flow cytometry. The intracellular catalase (CAT), superoxide dismutase (SOD), glutathione peroxidase (GSH-Px), glutathione s-transferase (GST), γ-glutamylcysteine synthetase (γ-GCS), and glutathione (GSH) contents were determined by colorimetric methods. CSTE content was determined by high performance liquid chromatography. The CSTE pretreatment improved survival rates in damaged HL-1 cells, reduced total intracellular ROS and MDA levels, and reduced apoptosis. The CSTE also increased the activities of the antioxidant enzymes (CAT, SOD, GSH-Px, and GST), as well as the γ-GCS and GSH levels in damaged cells. Real-time fluorescence quantitative polymerase chain reaction analysis indicated that the CSTE upregulated CAT, SOD1, and GSH-Px mRNA expression levels. Additionally, the CSTE reduced MDA and ROS levels in HL-1 cells by improving the endogenous antioxidant system; thus, alleviating the oxidative stress damage caused by AAPH. Our compositional analyses revealed that the CSTE contained caffeic acid, isoquercetin, rosmarinic acid, luteolin, and baicalin. The CSTE demonstrates antioxidant and protective effects in myocardial cells.

Cellular responses and microRNA profiling in bovine spermatozoa under heat shock

Sperm function is susceptible to adverse environmental conditions. It has been demonstrated that in vivo and in vitro exposure of bovine sperm to elevated temperature reduces sperm motility and fertilizing potential. However, the cascade of functional, cellular and molecular events triggered by elevated temperature in the mature sperm cell remains not fully understood. Therefore, the aim of this study was to determine the effect of heat shock on mature sperm cells. Frozen-thawed Holstein sperm were evaluated immediately after Percoll purification (0 h non-incubation control) or after incubation at 35°C, 38.5°C, and 41°C for 4 h. Heat shock reduced sperm motility after 3 - 4 h at 41°C while mitochondrial activity was reduced by 38.5 and 41°C when compared to the control. Heat shock also increased sperm reactive oxygen species production and caspase activity. Heat-shocked sperm had lower fertilizing ability, which led to diminished cleaved and blastocyst rates. Preimplantation embryo developmental kinetics was also slowed and reduced by sperm heat shock. The microRNA (miR) profiling identified >300 miRs in bovine sperm. Among these, three and seven miRs were exclusively identified in sperm cells exposed to 35 and 41°C, respectively.

Preparation, Antioxidant and Immunoregulatory Activities of a Macromolecular Glycoprotein from Salvia miltiorrhiza

Salvia miltiorrhiza has exhibited various bioactive functions due to the existence of polysaccharides, hydrophilic phenolic acids, diterpenoid quinones, and essential oils. However, little research has reported the glycoprotein preparation and corresponding bioactivities. In this study, the water-soluble glycoprotein from S. miltiorrhiza roots was firstly isolated with the extraction process optimized by response surface methodology, and then, the preliminary structural properties, and the antioxidant and immunoregulatory activities were investigated. Results showed that the extraction conditions for higher extraction yields were identified as follows: ultrasonic power of 220 W, ultrasonic time of 2.0 h, extraction temperature of 60 °C, liquid/solid ratio of 20 mL/g, and the glycoprotein yields of 1.63 ± 0.04%. Structural analysis showed that the glycoprotein comprised protein and polysaccharide (contents of 76.96% and 20.62%, respectively), with an average molecular weight of 1.55 × 10⁵ Da. Besides, bioactivities analysis showed that the glycoprotein presented strong scavenging effects on multiple free radicals, and effectively enhanced the antioxidant enzyme activities and immunological indicators in cyclophosphamide-induced immunocompromised mice dose-dependently. These data demonstrated that S. miltiorrhiza glycoprotein presented the potential to be a novel edible functional compound, and could be practically applied in the food industry.

Composition analysis and antioxidant activity evaluation of a high purity oligomeric procyanidin prepared from sea buckthorn by a green method

Procyanidin is an important polyphenol for its health-promoting properties, however, the study of procyanidin in sea buckthorn was limited. In this paper, sea buckthorn procyanidin (SBP) was obtained through a green isolation and enrichment technique with an extraction rate and purity of 9.1% and 91.5%. The structure of SBP was analyzed using Ultraviolet–visible spectroscopy (UV–vis), Fourier-transform infrared spectroscopy (FT-IR), and liquid chromatography-mass spectrometry (LC-MS/MS). The results show that SBP is an oligomeric procyanidin, mainly composed of (−)-epicatechin gallate, procyanidin B, (+)-gallocatechin-(+)-catechin, and (+)-gallocatechin dimer. SBP showed superior scavenging capacity on free radicals. Furthermore, the cleaning rate of the ABTS radical was 4.8 times higher than vitamin C at the same concentration. Moreover, SBP combined with vitamin C presented potent synergistic antioxidants with combined index values below 0.3 with concentration rates from 5:5 to 2:8. SBP also provided significant protection against oxidative stress caused by hydrogen peroxide (H₂O₂) on RAW264.7 cells. These findings prove the potential of SBP as a natural antioxidant in food additives and support the in-depth development of sea buckthorn resources.

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A green method for the extraction of procyanidin was proposed.

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An oligomeric procyanidin in sea buckthorn was identified for the first time.

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SBP combined with VC exerted strong synergistic antioxidant.

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SBP provided protection of macrophages against oxidative damage.