Effects of egg yolk and soybean lecithin on sperm quality determined by computer-assisted sperm analysis and confocal laser scanning microscope in chilled canine sperm

Comprehensive overview of the toxicities of small-molecule cryoprotectants for carnivorous spermatozoa: foundation for computational cryobiotechnology

Background

The specific and non-specific toxicities of cryoprotective agents (CPAs) for semen or spermatozoa cryopreservation/vitrification (SC/SV) remain challenges to the success of assisted reproductive technologies.

Objective

We searched for and integrated the physicochemical and toxicological characteristics of small-molecule CPAs as well as curated the information of all extenders reported for carnivores to provide a foundation for new research avenues and computational cryobiology.

Methods

The PubMed database was systematically searched for CPAs reported in SC/SV of carnivores from 1964 to 2024. The physicochemical features, ADMET parameters, toxicity classes, optimized structures, biological activities, thermodynamic equilibrium constants, and kinetic parameters were curated and assessed computationally.

Results

Sixty-two relevant papers pertaining to CPAs used in SC/SV were found, and 11 CPAs were selected. Among the properties of CPAs, the molecular weight range (59-758 g/mol), melting point (-60°C to 236°C), XlogP3 (-4.5 to 12.9), topological polar surface area (TPSA; 20-160 Å2), Caco2 permeability (-0.62 to 1.55 log(Papp) in 10-6 cm/s), volume of distribution (-1.04 to 0.19 log L/kg), unbound fraction of a CPA in plasma (0.198-0.895), and Tetrahymena pyriformis toxicity (log µg/L; -2.230 to 0.285) are reported here. Glutathione, dimethyl formamide, methyl formamide, and dimethyl sulfoxide were used as the P-glycoprotein substrates. Ethylene glycol, dimethyl sulfoxide, dimethyl formamide, methyl formamide, glycerol, and soybean lecithin showed Caco2 permeabilities in this order, whereas fructose, glutathione, glutamine, glucose, and citric acid were not Caco2-permeable. The CPAs were distributed in various compartments and could alter the physiological properties of both seminal plasma and spermatozoa. Low volume distributions of all CPAs except glucose indicate high water solubility or high protein binding because higher amounts of the CPAs remain in the seminal plasma.

Conclusion

ADMET information of the CPAs and extenders in the bipartite compartments of seminal plasma and intracellular spaces of spermatozoa are very important for systematic definition and integration because the nature of the extenders and seminal plasma could alter the physiology of cryopreserved spermatozoa.

Effects of Cryoprotectant Combinations on Post-Thawed Sperm Quality, Biomolecular Changes, DNA Methylation, and Pregnancy Rates in Boer Goat Semen

This study investigated the effects of various cryoprotectant combinations on post-thaw sperm quality, biomolecular changes, DNA methylation, and pregnancy rates using Boer goat semen. Synchrotron-based Fourier-transform infrared spectroscopy (SR-FTIR) was used to assess biomolecular changes. A Tris-based extender supplemented with 5% glycerol was used in combination with different concentrations of cryoprotectants, including 1% and 3% soybean lecithin and 10% and 18% egg yolk, with Andromed® serving as the control. SR-FTIR analysis revealed that the combination of 5% glycerol and 18% egg yolk (T4) resulted in significantly higher levels of lipids, ester lipids, and secondary protein structures (α-helix) compared with those under the other treatments (p < 0.05). Analysis of the principal component analysis (PCA) score plot and correlation loadings revealed a positive association between the cryoprotectant combination of T4 and increased levels of lipids and ester lipids, as well as enhanced sperm motility, progressive motility, and viability. Furthermore, this combination achieved a pregnancy and parturition rate of 66.67%, which was notably higher than the rate achieved with Andromed® (37.50%). Moreover, T4 did not show a significant difference in DNA methylation levels compared to Andromed® and fresh sperm (p > 0.05). Overall, the results indicated that specific cryoprotectant combinations play a key role in enhancing the biomolecular and functional integrity of freeze-thawed Boer goat semen.

Enhancing canine semen quality through a second centrifugation after 48 hours of storage: a comparative study

BACKGROUND

Centrifugation is a common procedure to improve the quality of chilled and frozen canine semen by removing debris and seminal plasma and adding semen extenders. The aim of this study was to evaluate the efficacy and influence of a second centrifugation after 48 h of storage at 5 °C on the sperm quality of canine semen. The ejaculates of 45 healthy male dogs, divided into three groups according to body weight, were analyzed for macro- and microparameters such as ejaculate volume, sperm concentration, kinematic parameters, morphology, and integrity of plasma membrane. Samples were analyzed at baseline conditions (T0), after 24 h (T24) and after 48 h (T48) to assess the effects of the different treatments on sperm quality.

RESULTS

The results showed a significant effect of a second centrifugation on the improvement of chilled sperm quality compared to the other techniques, especially up to 48 h.

CONCLUSIONS

Analysis of the data showed that the semen samples centrifuged and then cooled at 5 °C had acceptable semen parameters, especially in terms of motility, with a gradual decrease in serial evaluations after 24 and 48 h. A second centrifugation after 48 h of storage may lead to better semen quality and improve the kinetics of sperm parameters, the percentage of morphologically normal sperm and the percentage of sperm with intact membranes.

Low concentrations of soybean lecithin nanoparticles had a positive impact on Holstein bulls' cryopreserved semen

Spermatozoa can experience negative changes when subjected to freezing and thawing, including lowered motility, viability and acrosome response. Herein, the effects of different concentrations of soybean lecithin nanoparticles on cryopreserved Holstein bull semen were examined. Semen was collected, cryopreserved and utilized for sperm kinetic parameter analysis following dilution, equilibration and thawing with 0.5% soybean lecithin (E1), the control extender, and 0.75% (E2), 0.5% (E3), 0.25% (E4) and 0.125% (E5) of lecithin nanoparticles. Results revealed that following dilution, the progressive motility (PM) at E3, E4 and E5 of lecithin nanoparticles was higher (p < .05) than it was for E2. After equilibration, compared to the E1, E2, and E3 values, the PM, vitality, normal morphology, membrane integrity and intact acrosome values at the E5 were consistently greater (p < .05). Comparing the percentages of intact acrosome and membrane integrity at E2 and E3 to E4 and E5, a substantial decrease (p < .05) was seen. Following thawing, the percentage of PM improved at E2 and E5, even though their mean PM values were similar (p > .05) compared to E1, E3 and E4. Vigour and progression parameters of sperm (DAP, DCL, DSL, VAP, VCL, VSL and STR) at E5 were higher (p < .05) than those at E1, E2, E3 and E4. In conclusion, the cryopreserved sperm from Holstein bulls revealed outstanding properties both after equilibration and after thawing with 0.125% lecithin nanoparticles, and they were sensitive to high dosages.

Identifications of metabolic differences between Hedysari Radix Praeparata Cum Melle and Astragali Radix Praeparata Cum Melle for spleen-qi deficiency rats: A comparative study

Hedysari Radix Praeparata Cum Melle (HRPCM) and Astragali Radix Praeparata Cum Melle (ARPCM) are capable of improving spleen-qi deficiency (SQD) syndrome especially in the gastrointestinal dysfunction and decreased immunity in traditional Chinese medicine clinically. This study aims to compare and reveal the metabolic differences between HRPCM and ARPCM for SQD rats. Firstly, HRPCM (12.6 g/kg) and ARPCM (12.6 g/kg) were used to intervene SQD rats to further evaluate the effect. The results showed that HRPCM and ARPCM were able to improve the spleen pathology, increase the body weight, the rectal temperature, the spleen index, the thymus index, the levels of GAS and D-xylose in serum, and decrease the levels of IL-2, IL-6 and TNF-α in serum for SQD rats. Then, the studies of metabolic differences in serum and spleen were carried out using UPLC-Q-TOF-MS. The findings emphasized that HRPCM and ARPCM not only regulated metabolic profiling of serum and spleen in SQD rats, but also existed differences. HRPCM and ARPCM regulated metabolic pathways mainly including lipid metabolism, energy metabolism, amino acid metabolism, nucleotide metabolism, sugar metabolism and other types of metabolism for SQD rats. However, the metabolite profiles in SQD rats changed significantly, mainly involving abnormal glycine synthesis occurred in SQD rats. The expression trends of metabolites in HRPCM and ARPCM intervention for SQD rats were partly the same. Interestingly, there are similarities and differences in metabolic profiling between HRPCM and ARPCM for SQD rats. The differences were mainly in the synthesis of L-glutamine in amino acid metabolism.

Perspectives on lecithin from egg yolk: Extraction, physicochemical properties, modification, and applications

Egg yolk lecithin has physiological activities as an antioxidant, antibacterial, anti-inflammatory, and neurologic, cardiovascular, and cerebrovascular protectant. There are several methods for extracting egg yolk lecithin, including solvent extraction and supercritical extraction. However, changes in extraction methods and functional activity of egg yolk lecithin are a matter of debate. In this review we summarized the molecular structure, extraction method, and functional activity of egg yolk lecithin to provide a good reference for the development of egg yolk lecithin products in the future.

The Effect of Different Extenders on the Quality Characteristics of European Red Deer Epididymal Sperm Stored at 5 °C

The aim of this study was to evaluate the effect of different extenders on the quality of European red deer epididymal sperm stored at 5 °C. Epididymal spermatozoa were collected post mortem from 10 stags and diluted with three extenders (Bovidyl®, BoviFree®, and BioXcell®) and stored at 5 °C. Sperm motility (TMOT), motility parameters (system CASA), plasma membrane integrity (SYBR-14+/PI−), acrosomal membrane integrity (FITC-PNA−/PI−), mitochondrial activity (JC-1/PI), viability, and apoptotic-like changes (YOPRO/PI) were evaluated. The analyses were conducted on the first and successive days of storage (D1−D7). The applied extender, storage time, and the interactions between these factors significantly (p < 0.001) affected most of the analyzed parameters whose values were highest in sperm samples stored in Bovidyl®, regardless of storage time. In Bovidyl®, BoviFree®, and BioXcell® extenders, TMOT values were estimated at 83%, 63%, and 59%, respectively, on D3. The extenders significantly influenced DNA integrity on D7. The percentage of dead sperm increased from D3. The quality of stored sperm cells was significantly influenced by the extenders’ biochemical composition. BoviFree® and BioXcell® contain glycerol which could contribute to deteriorating the quality of spermatozoa stored at 5 °C. Sperm cells stored in the egg yolk-based extender (Bovidyl®) were characterized by the highest viability and functionality.

Evaluation of Chilled Dog Semen Extended With Sperm Activator

Within modern biotechnology, different tools and methodologies have been developed to maximize canine semen conservation protocol to optimize reproductive results. In the last decades, the survival of chilled semen has been prolonged from 2 to 3 days with the first basic diluents, to 10–14 days with the modern extenders. However, their main limitation is that sperm quality decreases during cold storage. Sperm activators (SA) have been produced to provide the molecules necessary to maximize the sperm survival and quality with the aim to enhance fertility and prolificacy. In this study, the effect of commercial extender SA (Theriosolution® Canine AI extender -Chile-) was recorded by daily evaluation of chilled semen for 14 days. In this experiment, sperm-rich ejaculate fraction was collected from six adult healthy Neapolitan Mastiff dogs. The semen evaluation started immediately after collection (d0), and after that a next generation extender was added (d0) for every 24 h from d1 (with and without SA) to d14, to determine spermatozoa progressive motility, velocity of forward progression (VFP), morphology, and integrity of the spermatic membrane. The initial sperm concentration of extended semen was 417.3 ± 170.4 x 106/mL (mean ± SEM) with 85.89 ± 4.76% of MNS (morphologically normal sperm), 84.47 ± 5.22 % live sperm, and pH of 6.2 ± 2.8. The initial VFP was 3.83 ± 0.48, but after 1 min with SA, it rises to 4.45 ± 0.45 (P &lt; 0.001). The sperm progressive motility parameter increases significantly (P &lt; 0.05) in experimental trial, respect to control, starting to d2 at finish (except for d7). The VFP analysis significantly increases in experimental trial (P &lt; 0.05) during most days of the study with the exclusion of d3 and d14. To evaluate the seminal characteristics over time, the experiment was divided into T1 (d0–d5), T2 (d6–d10), and T3 (d11–d14) (P &lt; 0.001) in evaluation of morphology and membrane functionality. The MNS reached 70% at d10 and finally 65% at d14, being considered normal and possibly fertile. With Host-s, 65% of MNS were also achieved at d14. The presence of glucose and fructose in the diluents used for refrigeration can exert very important effects given the fact that metabolic routes have been found in both sugars, providing both different and complementing effects. It can be concluded that the use of SA prior to artificial insemination improves the quality of chilled semen significantly, although it does not reverse the effects of deterioration due to cellular metabolism over time.

The Use of κ-Carrageenan in Egg Yolk Free Extender Improves the Efficiency of Canine Semen Cryopreservation

κ-Carrageenan is a plant polysaccharide derived from red seaweeds reported to possess potential medicinal and antioxidants activities. The present study aimed to identify the cryoprotective effects of κ-carrageenan on the quality of frozen-thawed canine semen. Twenty-eight ejaculates were collected and diluted in a Tris egg-yolk-free extender supplemented with various concentrations of κ-carrageenan (0.0%, 0.1%, 0.2%, 0.3%, and 0.5%). The addition of κ-carrageenan to the extender at a 0.2% concentration induced a significant increase in the total motility (TM) and the rapid progressive motility (RPM) of canine sperm. Among the experimental groups, the highest percentage of sperms with intact acrosomes was found in the 0.5% κ-carrageenan group (p < 0.05). Apoptosis levels were significantly lower in the 0.1% and 0.2% κ-carrageenan treatment. Moreover, sperm in the κ-carrageenan supplemented group showed a significantly higher expression of antiapoptotic (Bcl-2) and lower expression of NADPH oxidase (NOX5), spermine synthase (SMS), and spermine oxidase (SMOX) genes than those in the control group. In conclusion, the addition of κ-carrageenan to the freezing extender improved the overall efficiency of frozen-thawed dog spermatozoa.

The possibility of using citric phosphate dextrose in chilling ram semen instead of egg yolk and soybean lecithin to improve fertility

Semen chilling has some harmful effects on sperm characteristics. Modification of extenders by using conventional and non-conventional chilling substances can affect sperm characteristics and fertility. One of the important substances using to chilling human blood cells is citric phosphate dextrose (CPD); therefore, it can be used to store ram semen. This study aimed to assay the ability of CPD instead of egg yolk (EGD) and soybean lecithin (SLD)-based extenders to store ram semen at 5°C. This trial was carried on pooling semen samples that were collected from five rams using a standard artificial vagina and an oestrous restrained ewe. Immediately after semen collection, semen was divided into four portions. The EGD, SLD and citric phosphate dextrose with an antibiotic (CPDA) and without antibiotic (CPD) were extender in the first, second, third and fourth portions of semen, respectively. Sperm characteristics were evaluated after dilution and cooling up to 7 days. Also, conception rate and fertility potential were assayed by 48 ewes (12 each) after 2 days of store ram semen extenders. Data clearly indicated that higher (p > .05) sperm characteristics in EGD, SLD and CPDA than CPD at 0 day of storage. Whilst, sperm characteristics from 1 day up to 7 days of storage were higher (p < .05) in EGD, SLD, CPDA extenders than CPD. Moreover amongst extender types, the advancing of chilling days reduced sperm characteristics. Also, the results showed an acceptable conception rate and the fertility rate of dilution ram semen, which stored 2 days in EGD, SLD and CPDA than CPD. Using of CPD substances with antibiotic in chilling extension ram semen has benefits as well as EGD- and SLD-based extenders. The future work should be conducted to validate these results in frozen ram semen.

Addition of butylated hydroxytoluene (BHT) in tris-based extender improves post-thaw quality and motion dynamics of dog spermatozoa

The aim of this study was to evaluate the interaction of different concentrations of butylated hydroxytoluene (BHT) in a tris-based extender on semen quality parameters in post-thawed dog semen. Twenty-four ejaculates were collected from eight male Beagle dogs using an artificial vagina. Pooled semen was diluted with a tris-based extender supplemented with 0 (control), 0.5, 1.0, 1.5, and 2.0 mM BHT, at a final concentration of 200 × 10⁶ spermatozoa/mL. After thawing, sperm samples were assessed for motility parameters (CASA), membrane integrity (SYBR-14/PI), acrosome integrity (FITC-PNA), mitochondrial activity (JC-1/PI), malondialdehyde (MDA) concentration, and glutathione peroxidase (GPx) activity. The total motility, progressive motility, and average path velocity of the frozen-thawed sperm were significantly higher in the BHT1.5 group than in the control and the other sample groups (P < 0.05). Higher values of straight-line velocity, curvilinear velocity, amplitude of the lateral head displacement, and linearity were observed in the BHT1.0, BHT1.5, and BHT2.0 groups than in the control (P < 0.05). The BHT1.0 and BHT1.5 groups had higher percentages of straightness and acrosome integrity than the other groups (P < 0.05). Beat cross frequency, plasma membrane integrity, and GPx activity of the BHT1.5 and BHT2.0 groups were higher than those of the control (P < 0.05). A lower concentration of MDA was observed in the BHT1.0, BHT1.5, and BHT2.0 groups than in the control (BHT0) (P < 0.05). Our results indicate that 1.5 mM BHT is the optimal concentration for improving the post-thaw quality of canine spermatozoa.