Effects of Taurine or Trehalose supplementation on functional competence of cryopreserved Karan Fries semen

Taurine induces hormesis in multiple biological models: May have transformative implications for overall societal health

This paper represents the first integrative assessment and documentation of taurine-induced hormetic effects in the biological and biomedical areas, their dose response features, mechanistic frameworks, and possible public health, therapeutic and commercial applications. Taurine-induced hormetic effects are documented in a wide range of experimental models, cell types and for numerous biological endpoints, with most of these experimental findings being reported within the past five years. It is suggested that the concept of hormesis may have a transformative effect on taurine research and its public health and therapeutic applications.

Effect of Trehalose Supplementation in Egg-Yolk-Free Extender on Conventional Parameters and Gene Expression Related to Reactive Oxygen Species, Apoptosis, and Motility of Frozen Dog Spermatozoa

The present study was conducted to evaluate the effects of trehalose supplementation in egg-yolk (EY)-free tris extender on dog spermatozoa. Pooled spermatozoa were diluted with extender 1 (EY-free tris extender supplemented with 0, 10, 15, 20, or 30 mM trehalose) and cooled (2 × 108 sperm/mL) for 1 hour at 4°C. After that, extender 2 (extender 1 containing 1 M glycerol) was added (v:v) to the diluted sperm, loaded in 0.5-mL straws (1 × 108 sperm/mL), and incubated at 4°C for 30 minutes. The sperm straws were frozen over liquid nitrogen (LN2) vapor for 20 minutes and then plunged directly into LN2. After thawing at 37°C for 25 seconds, sperm progressive motility (CASA), viability (SYBR-14/PI), apoptosis (Annexin V/PI), and reactive oxygen species (ROS; H2DCFDA/PI) were evaluated. Thereafter, the optimal concentrations of trehalose were selected, and the gene expression of BAX, BCL2, NOX5, SMOX, OGG1, and ROMO1 was evaluated after freeze-thawing. Supplementation with 20 and 30 mM trehalose significantly increased sperm progressive motility and viability compared to the control. However, trehalose had no significant effect on sperm ROS or phosphatidylserine translocation index. There were minor numerical increases and decreases in gene expression when the selected optimal concentrations of trehalose (20 and 30 mM) were compared to the control. However, there were no significant differences. We conclude that the addition of trehalose (20 and 30 mM) in EY-free extender could improve sperm motility and viability without significant effects on ROS, apoptosis, or gene expression.

Recovering Spermatogenesis By Protected Cryopreservation Using Metformin and Transplanting Spermatogonial Stem Cells Into Testis in an Azoospermia Mouse Model

Cryopreservation and transplantation of spermatogonial stem cells (SSCs) may serve as a new method to restore male fertility in patients undergoing chemotherapy or radiotherapy. However, SSCs may be damaged during cryopreservation due to the production of reactive oxygen species (ROS). Therefore, different antioxidants have been used as protective agents. Studies have shown that metformin (MET) has antioxidant activity. The aim of this study was to assess the antioxidant and antiapoptotic effects of MET in frozen-thawed SSCs. In addition, the effect of MET on the proliferation and differentiation of SSCs was evaluated. To this end, SSCs were isolated from mouse pups aged 3-6 days old, cultured, identified by flow cytometry (ID4, INTEGRIN β1+), and finally evaluated for survival and ROS rate. SSCs were transplanted after busulfan and cadmium treatment. Cryopreserved SSCs with and without MET were transplanted after 1 month of cryopreservation. Eight weeks after transplantation, the recipient testes were evaluated for the expression of apoptosis (BAX, BCL2), proliferation (PLZF), and differentiation (SCP3, TP1, TP2, PRM1) markers using immunohistochemistry, Western blot, and quantitative real-time polymerase chain reaction. The findings revealed that the survival rate of SSCs was higher in the 500 μm/mL MET group compared to the other groups (50 and 5000 μm/mL). MET significantly decreased the intracellular ROS production. Transplantation of SSCs increased the expression level of proliferation (PLZF) and differentiation (SCP3, TP1, TP2, PRM1) markers compared to azoospermia group, and their levels were significantly higher in the MET group compared to the cryopreservation group containing basic freezing medium (p < 0.05). MET increased the survival rate of SSCs, proliferation, and differentiation and decreased the ROS production and the apoptosis rate. Cryopreservation by MET seems to be effective in treating infertility.

Monitoring of taurine dietary supplementation effect on parameters of Duroc boar ejaculate in summer season

The aim of this experiment was to find out whether the taurine supplementation in daily ration had an effect on quantity or quality of Duroc boar ejaculate. The experiment duration was from June to August, when it could assumed the possible occurrence of heat stress. For the study was chosen 12 Duroc boars of approximately the same age and condition. The control group of 6 Duroc boars was fed only by basic diet and the experimental group of 6 Duroc boars was fed by the same basic diet with supplementation of 15 g taurine/boar/day. Ejaculate was collected once a week by hand glowed technique. From ejaculate parameters were monitored volume of ejaculate, sperm concentration, total amount of sperm, morphologically abnormal sperm, taurine concentration and GSH/GSSH concentration. From microscopic analysis, results were statistically significant in motility in June and July (P<0.05). In biochemical results, a significant difference (P<0.05) has been found between the experimental groups in the concentrations of taurine as well as GSH/GSSG in ejaculate which indicates the effect of heat stress on boars during the experimental period.

Seasonal influence on expression of heat shock proteins (HSP70 and HSP90) vis-à-vis functional competence of Gir bull semen

The success of assisted reproduction relies on functional competence of frozen-thawed semen. Heat stress affects protein folding leading to aggregation of mis-folded proteins. Hence, a total of 384 (32 ejaculates/bull/season) ejaculates from six matured Gir bulls were used to evaluate physico-morphological parameters, the expression of HSPs (70 and 90) and fertility of frozen-thawed semen. The mean percent individual motility, viability and membrane integrity were significantly (p < 0.01) higher in winter compared to summer. Out of 1200 Gir cows inseminated, 626 confirmed pregnant and the mean conception rate of winter (55.04 ± 0.35) was significantly (p < 0.001) higher than summer (49.33 ± 0.32). A significant (p < 0.01) difference in concentration of HSP70 (ng/mg of protein) but not HSP90was observed between the two seasons. The HSP70 expression in pre-freeze semen of Gir bulls had significant positive correlation with motility (p < 0.01, r = 0.463), viability (p < 0.01, r = 0.565), acrosome integrity (p < 0.05, r = 0.330) and conception rate (p < 0.01, r = 0.431). In conclusion, the season influences physico-morphological parameters and expression of HSP70 but not HSP90 in Gir bull semen. The HSP70 expression is positively correlated with motility, viability, acrosome integrity and fertility of semen. The semen expression of HSP70 may be utilized as biomarker for thermo-tolerance, semen quality and fertilizing capacity of Gir bull semen.

Freezability and Fertility Rates of Stallion Semen Supplemented With Trehalose in Lactose Extender

Cryopreservation of stallion semen is often associated with poor post-thaw sperm quality. One of the reason for this diminished quality is osmotic stress that spermatozoa experiences during freezing and thawing process. The aim of the present study was to evaluate the cryoprotective effect of trehalose on stallion sperm quality and field fertility rates subjected to cooling and freeze-thawing process. Semen samples were collected from six Marwari breed stallions, divided into three different treatments in a final concentration of 150 × 106 sperm/mL by using Lactose based extender containing 0, 50, and 150 mM of trehalose then subjected to cryopreservation after equilibration. Sperm motility, acrosome integrity, plasma membrane integrity, mitochondrial membrane potential, DNA integrity and oxidative stress related parameters of the stallion spermatozoa were analyzed at fresh, prefreeze and post thaw stages. Thirty (30) reproductively healthy mares were inseminated with frozen-thawed semen either supplemented with (treatment) or without (control) trehalose to evaluate the field fertility. Results of the current study indicated that, the extender containing 50 mM trehalose has enhanced the functional plasma membrane, acrosomal, DNA integrities and augmented the mitochondrial membrane potential. Trehalose supplementation to the semen extender not only ameliorated the semen quality parameters, but also protected the stallion sperm from oxidative stress by reducing the levels of reactive oxygen species (ROS) and lipid peroxidation (LPO). The inclusion of 50 mM trehalose in semen extender resulted in significantly (P < .05) increased post-thaw progressive motility and viability compared to the control group. Mares inseminated with frozen-thawed semen supplemented with 50 mM trehalose tended to have better pregnancy rates than controls (non-significant [P < .05]) although a larger fertility trial is required to determine if this effect reaches the level of significance. In conclusion, addition of 50 mM trehalose yielded in better quality stallion semen after cooling and post-thawing in terms of reducing the oxidative stress and enhancing the motility, integrities of acrosome, plasma membrane, mitochondrial potential and DNA.

Role of antioxidants in fertility preservation of sperm - A narrative review

Male fertility is affected by multiple endogenous stressors, including reactive oxygen species (ROS), which greatly deteriorate the fertility. However, physiological levels of ROS are required by sperm for the proper accomplishment of different cellular functions including proliferation, maturation, capacitation, acrosomal reaction, and fertilization. Excessive ROS production creates an imbalance between ROS production and neutralization resulting in oxidative stress (OS). OS causes male infertility by impairing sperm functions including reduced motility, deoxyribonucleic acid damage, morphological defects, and enhanced apoptosis. Several in-vivo and in-vitro studies have reported improvement in quality-related parameters of sperm following the use of different natural and synthetic antioxidants. In this review, we focus on the causes of OS, ROS production sources, mechanisms responsible for sperm damage, and the role of antioxidants in preserving sperm fertility.

The role of taurine in male reproduction: Physiology, pathology and toxicology

Taurine, a sulfur-containing amino acid, has a wide range of biological effects, such as bile salt formation, osmotic regulation, oxidative stress inhibition, immunomodulation and neuromodulation. Taurine has been proved to be synthesized and abundant in male reproductive organs. Recently, accumulating data showed that taurine has a potential protective effect on reproductive function of male animals. In physiology, taurine can promote the endocrine function of the hypothalamus-pituitary-testis (HPT) axis, testicular tissue development, spermatogenesis and maturation, delay the aging of testicular structure and function, maintain the homeostasis of the testicular environment, and enhance sexual ability. In pathology, taurine supplement may be beneficial to alleviate pathological damage of male reproductive system, including oxidative damage of sperm preservation in vitro, testicular reperfusion injury and diabetes -induced reproductive complications. In addition, taurine acts as a protective agent against toxic damage to the male reproductive system by exogenous substances (e.g., therapeutic drugs, environmental pollutants, radiation). Related mechanisms include reduced oxidative stress, increased antioxidant capacity, inhibited inflammation and apoptosis, restored the secretory activity of the HPT axis, reduced chromosomal variation, enhanced sperm mitochondrial energy metabolism, cell membrane stabilization effect, etc. Therefore, this article reviewed the protective effect of taurine on male reproductive function and its detailed mechanism, in order to provide reference for further research and clinical application.

Butylated Hydroxytoluene (BHT) Improves the Post-Thaw Semen Quality in Low-Dose Sperm Cryopreservation in Murrah Buffalo Bull

BACKGROUND: Cryopreservation is an important technique for the long-term storage of semen for artificial insemination (AI). Buffalo spermatozoa are sensitive to cryopreservation procedures because of the presence of a high amount of polyunsaturated fatty acids in the plasma membrane. OBJECTIVE: To study the effect of different concentrations of BHT on the quality of Murrah buffalo bull semen for low-dose cryopreservation. MATERIAL AND METHODS: Semen was collected from four high fertile Murrah buffalo bulls (6 ejaculates each) using an artificial vagina. A total of 24 ejaculates were collected from each bull twice a week using an artificial vagina. Every sample was split into four parts: Control without additives; and three treatments with BHT at 0.5 mM, 1 mM or 2 mM. Semen was cryopreserved at low-dose sperm cryopreservation of 20, 15, 10 and 5 million sperm per aliquot after supplementation of BHT. Semen samples were evaluated for fresh, pre-freeze and post-thaw stages. RESULTS:There was a significant increase (p<0.05) in sperm quality parameters, such as progressive motility (%), viability (%), HOST response (%), acrosome integrity (%) and post-thaw motility, with the addition of 0.5-1 mM BHT. CONCLUSION: The addition of BHT in Murrah buffalo semen improves the low dose cryopreservation quality in a dose-dependent manner.

Beneficial effects of trehalose and gentiobiose on human sperm cryopreservation

The protection of human sperm during cryopreservation is of great importance to infertility. Recent studies have shown that this area is still a long way from its ultimate aim of maintaining the maximum viability of sperm in cryopreservation. The present study used trehalose and gentiobiose to prepare the human sperm freezing medium during the freezing-thawing. The freezing medium of sperm was prepared with these sugars, and the sperm were then cryopreserved. The viable cells, sperm motility parameters, sperm morphology, membrane integrity, apoptosis, acrosome integrity, DNA fragmentation, mitochondrial membrane potential, reactive oxygen radicals, and malondialdehyde concentration was evaluated using standard protocols. A higher percentage of the total and progressive motility, rate of viable sperm, cell membrane integrity, DNA and acrosome integrity, and mitochondrial membrane potential were observed in the two frozen treatment groups compared to the frozen control. The cells had less abnormal morphology due to treatment with the new freezing medium than the frozen control. The higher malondialdehyde and DNA fragmentation were significantly observed in the two frozen treatment groups than in the frozen control. According to the results of this study, the use of trehalose and gentiobiose in the sperm freezing medium is a suitable strategy for sperm freezing to improve its motion and cellular parameters.

Taurine as a Natural Antioxidant: From Direct Antioxidant Effects to Protective Action in Various Toxicological Models

Natural antioxidants have received tremendous attention over the last 3 decades. At the same time, the attitude to free radicals is slowly changing, and their signalling role in adaptation to stress has recently received a lot of attention. Among many different antioxidants in the body, taurine (Tau), a sulphur-containing non-proteinogenic β-amino acid, is shown to have a special place as an important natural modulator of the antioxidant defence networks. Indeed, Tau is synthesised in most mammals and birds, and the Tau requirement is met by both synthesis and food/feed supply. From the analysis of recent data, it could be concluded that the direct antioxidant effect of Tau due to scavenging free radicals is limited and could be expected only in a few mammalian/avian tissues (e.g., heart and eye) with comparatively high (>15-20 mM) Tau concentrations. The stabilising effects of Tau on mitochondria, a prime site of free radical formation, are characterised and deserve more attention. Tau deficiency has been shown to compromise the electron transport chain in mitochondria and significantly increase free radical production. It seems likely that by maintaining the optimal Tau status of mitochondria, it is possible to control free radical production. Tau's antioxidant protective action is of great importance in various stress conditions in human life, and is related to commercial animal and poultry production. In various in vitro and in vivo toxicological models, Tau showed AO protective effects. The membrane-stabilizing effects, inhibiting effects on ROS-producing enzymes, as well as the indirect AO effects of Tau via redox balance maintenance associated with the modulation of various transcription factors (e.g., Nrf2 and NF-κB) and vitagenes could also contribute to its protective action in stress conditions, and thus deserve more attention.

Deciphering metabolomic alterations in seminal plasma of crossbred (Bos taurus X Bos indicus) bulls through comparative deep metabolomic analysis

The incidence of sub-fertility is higher in crossbred bulls compared to zebu bulls. In the present study, we analysed the metabolomic profile of seminal plasma from crossbred and zebu bulls and uncovered differentially expressed metabolites between these two breeds. Using a high-throughput LC-MS/MS-based approach, we identified 990 and 1,002 metabolites in crossbred and zebu bull seminal plasma respectively. After excluding the exogenous metabolites, we found that 50 and 68 putative metabolites were unique to crossbred and zebu bull seminal plasma, respectively, whilst 87 metabolites were common to both. After data normalisation, 63 metabolites were found to be dysregulated between crossbred and zebu bull seminal plasma. Observed pathways included Linoleic acid metabolism (observed metabolite was phosphatidylcholine) in crossbred bull seminal plasma whereas inositol phosphate metabolism (observed metabolites were phosphatidylinositol-3,4,5-trisphosphate/inositol 1,3,4,5,6-pentakisphosphate/myo-inositol hexakisphosphate) was observed in zebu bull seminal plasma. Abundance of Tetradecanoyl-CoA was significantly higher, whilst abundance of Taurine was significantly lower in crossbred bull seminal plasma. In conclusion, the present study established the seminal plasma metabolomic profile in crossbred and zebu bulls and suggest that increased lipid peroxidation coupled with low concentrations of antioxidants in seminal plasma might be associated with high incidence of sub-fertility in crossbred bulls.

Effects of Taurine on Sperm Quality during Room Temperature Storage in Hu Sheep

Simple Summary

Hu sheep sperm is highly susceptible to ROS during storage at room temperature. It is very important to use an antioxidant to ameliorate oxidative damage. Tau is an important amino acid peptide antioxidant with a wide range of biological effects. It can effectively scavenge free radicals, regulate reproductive function, improve immunity, and enhance its antioxidant capacity. However, the effects of Tau in the preservation of Hu sheep semen at room temperature are unclear. Therefore, Tau was added to Hu sheep semen preserved at room temperature to explore its effect on semen. The results showed that adding an appropriate concentration of Tau had a positive effect on Hu sheep semen preserved at room temperature; in particular, 20 mM Tau performed best.

Abstract

The present study aimed to investigate whether the presence of Tau protected Hu sheep sperm from ROS stress during storage at room temperature. The semen was diluted with extender (Tris-based) at room temperature, supplemented with different concentrations of Tau (0, 10, 20, 40, 80, or 100 mM), and stored at 15 °C. Sperm quality parameters (sperm progressive motility, kinetic parameters, plasma membrane integrity rate, acrosome integrity rate, and MMP) and antioxidant parameters (ROS, MDA, SOD, CAT, and T-AOC) were evaluated during the preservation of semen. The addition of Tau, especially at a concentration of 20 mM, exerted positive effects on sperm quality parameters and antioxidant parameters compared to the sperm without Tau treatment (control group). The addition of Tau, especially at a concentration of 100 mM, exerted negative effects on sperm quality parameters and antioxidant parameters compared to the control group. Interestingly, the results indicated that the sperm acrosome integrity rate did not change during storage time. In conclusion, the addition of Tau to sperm preserved at room temperature can enhance the antioxidant ability of sperm, reduce the LPO on the 5th day, and improve the quality of semen preserved at room temperature. These results implied that Tau had potential to enhance Hu sheep sperm reproductive performance.

The effect of L-glutamine and trehalose on dog sperm cryopreservation

This study aimed to test different doses of L-glutamine and trehalose in the canine semen diluent while determining their protective effects on spermatological and biochemical indices of the thawed samples. Semen samples were collected from three fertile dogs using the digital manipulation method. The mixed ejaculates were divided into five portions at 37 °C and diluted with additives. Five study groups were formed with L-glutamine (10 and 20 mM), trehalose (25 and 50 mM), and no additives (control). After the dilution, the semen samples were cooled for 1.5 h at 5 °C and frozen (-110 to -120 °C) in liquid nitrogen vapor. Then, they were stored at -196 °C. For spermatological evaluations, samples were thawed at 38 °C for 30 s. L-glutamine (20 mM) was found to be significantly different (P < 0.05) and led to higher percentages of motility, membrane integrity, and acrosome integrity compared to the control group. Considering the total oxidant status (TOS) assay, the lower values were determined in all the antioxidant groups compared to the control group (P < 0.05). Supplementing the semen extender with L-glutamine showed a higher total antioxidant status (TAS) concentration compared to the control group (P < 0.05). As a result of this study, a higher protective effect was found in all the spermatological evaluations after thawing the frozen semen samples, especially in the group containing L-glutamine (20 mM).

Trehalose Attenuates Detrimental Effects of Freeze-Drying on Human Sperm Parameters

Freeze-drying is one of the sperm preservation methods leading to the long-term preservation of sperm genetic material. Our main goal of this study was to evaluate the effect of the trehalose freeze-drying method on sperm motility, viability, morphology, acrosome, and DNA integrity compared with a standard protocol without trehalose. Twenty-five normozoospermic samples were included in this prospective study. Direct swim-up was used for sperm preparation. An experiment was performed on freeze-dried samples containing trehalose (0.2 M), and the results were compared to that without trehalose. The sperm parameters, including count, motility, morphology, viability, acrosome reaction, DNA denaturation, and DNA fragmentation, were evaluated before and after freeze-drying in both groups. The spermatozoa were totally immotile after freeze-drying in both groups. Sperm viability, acrosome integrity, and nondenatured sperm DNA were significantly higher in the trehalose group in comparison with that of without trehalose group. Nonfragmented sperm DNA showed an increasing trend in the trehalose group compared to the group without trehalose. While freeze-drying significantly reduced normal morphology, the addition of trehalose did not affect this parameter. The results of this study showed that trehalose can attenuate the detrimental effects of freeze-drying on human sperm parameters.

Preliminary comparative deep metabolomic analysis of spermatozoa from zebu and crossbred cattle suggests associations between metabolites, sperm quality and fertility

Poor semen quality and infertility/subfertility are more frequent in crossbred than zebu bulls. Using a high-throughput liquid chromatography–tandem mass spectrometry (LC-MS/MS)-based approach, we established the preliminary metabolomic profile of crossbred and zebu bull spermatozoa (n=3 bulls each) and identified changes in sperm metabolomics between the two groups. In all, 1732 and 1240 metabolites were detected in zebu and crossbred bull spermatozoa respectively. After excluding exogenous metabolites, 115 and 87 metabolites were found to be unique to zebu and crossbred bull spermatozoa respectively whereas 71 metabolites were common to both. In the normalised data, 49 metabolites were found to be differentially expressed between zebu and crossbred bull spermatozoa. The significantly enriched (P&lt;0.05) pathways in spermatozoa were taurine and hypotaurine metabolism (observed metabolites taurine and hypotaurine) in zebu and glycerophospholipid metabolism (observed metabolites phosphatidylcholine, phosphatidylethanolamine and phosphatidylserine) in crossbred bulls. The abundance of nitroprusside (variable importance in projection (VIP) score &gt;1.5) was downregulated, whereas that of l-cysteine, acetyl coenzyme A and 2′-deoxyribonucleoside 5′-diphosphate (VIP scores &gt;1.0) was upregulated in crossbred bull spermatozoa. In conclusion, this study established the metabolomic profile of zebu and crossbred bull spermatozoa and suggests that aberrations in taurine, hypotaurine and glycerophospholipid metabolism may be associated with the higher incidence of infertility/subfertility in crossbred bulls.

Protective effects of Tribulus terrestris and Cinnamomum zeylanicum extracts and trehalose added to diluents on goat epididymal sperm freezability

This study investigates the effect of adding Tribulus terrestris ethanol extract (TEE) and Cinnamomum zeylanicum ethanol extract (CEE) and trehalose on freezability of goat epididymal spermatozoa. In Experiment 1, the treatments consist of basic extender containing 25, 50 or 100 μg/ml of TEE or CEE. The control contained no additives. Experiment 2 was carried out to compare the effect of best concentrations resulted in the first experiment with 150 mM trehalose added to basic extender. The results of experiment 1 showed that supplementation of 50 μg/ml TEE and 50 μg/ml CEE increased significantly the percentages of motility, progressive motility and viability of cryopreserved spermatozoa, while the level of malondialdehyde concentration was decreased. Moreover, the 50 μg/ml TEE treatment indicate significantly) P < 0.05) the lowest DNA fragmentation among the other treatments. The data obtained from experiment 2 show that all treatments increased significantly) P < 0.05) the percentages of total motility, viability and membrane integrity, and concurrently decreased the rate of MDA compared to control. In addition, the rates of viability and progressive motility were significantly (P < 0.05) higher in diluents contained herb extracts and trehalose. Regarding DNA fragmentation, the results demonstrate that using the extracts and trehalose in diluents decreased the DNA damages and thereby improved the rate of intact sperm heads. In conclusion, the results of this study indicate that 50 μg/ml of Tribulus terrestris and Cinnamomum zeylanicum ethanolic extracts alone and plus trehalose improved the spermatozoa quality and could be used for cryopreservation.

Caffeic acid improves microscopic sperm parameters and antioxidant status of buffalo (Bubalus bubalis) bull semen following freeze-thawing process

This study investigates the effects of cryopreservation and supplementation of buffalo's semen with Caffeic acid. It studies the effects of different Caffeic acid concentrations on cryopreservation capacity of the buffalo and evaluates their influence on various sperm parameters like motility, viability, progressive motility, sperm plasma membrane integrity, and antioxidant status. Twenty-four semen samples were collected with an artificial vaginal from three adult water buffalos. The semen samples were evaluated and the qualified ejaculates were separated and were diluted in a Tris-based extender. The resulting samples were classified into 5 groups: No antioxidant (control), Control sham (NaOH), Caffeic acid 50 μM, Caffeic acid 100 μM, and Caffeic acid 200 μM. The semen samples encountered cryodamage and the quality was deteriorating during the cryopreservation (P < 0.05). The semen evaluation after thawing showed that the groups of samples receiving 100 μM Caffeic acid had higher viability, total motility, and lower abnormal sperm and better linearity (LIN), curvilinear velocity (VCL), straight-line velocity (VSL) and path velocity and higher intact plasma membrane (P < 0.05) compared to other groups. It is notable that adding 100 μM Caffeic acid to freezing extenders enhances the CAT, GPx, SOD, and GSH and also ameliorates total antioxidant capacity of spermatozoa after thawing. It is notable that the addition of 100 μM Caffeic acid decreases the amount of Malondialdehyde. These reactions lead us to conclude that 100 μM Caffeic acid enhances the semen quality of water buffalo after thawing.

Effect of the addition of six antioxidants on sperm motility, membrane integrity and mitochondrial function in red seabream (Pagrus major) sperm cryopreservation

The present study was to evaluate the effects of six antioxidants on frozen-thawed sperm motility, viability, membrane integrity and mitochondrial function in red seabream (Pagrus major) by computer-assisted sperm analysis system and flow cytometry, respectively. All the parameters tested in this study were determined using one-way ANOVA and identified using the SNK test (P < 0.05). The results demonstrated that on the first day, the highest motility and longevity occurred in 100 mM trehalose (78.34 ± 3.41%, 29 ± 4.00 days) and 50 mM taurine (77.46 ± 1.54%, 29.33 ± 4.04 days), followed by 25 mM vitamin C (79.03 ± 5.37 %, 17 ± 1.00 days), 25 mM vitamin E (69.64 ± 1.64%, 27.67 ± 1.53 days) and 25 mM vitamin A (78.89 ± 2.81%, 9.33 ± 1.53 days), which were all higher than frozen-thawed sperm without antioxidant (control) (66.80 ± 5.55, 5.67 ± 1.15 days). Especially, the percentages of class A sperm with the addition of 100 mM trehalose (40.39 ± 5.20%) and 50 mM taurine (37.78 ± 3.22%) were significantly improved compared to the control (19.63 ± 5.44%). The viability of all groups on the third and sixth day showed a similar trend. Moreover, during the 4 °C storage process, the decrease of frozen-thawed sperm motility was closely associated with the decrease in membrane integrity and mitochondrial function. In conclusion, the present study indicated that antioxidant (100 mM trehalose and 50 mM taurine) provided the most pronounced protective effect in improving frozen-thawed quality of red seabream sperm. The addition of antioxidant may be capable of scavenging the ROS generated during the cryopreservation process and 4 °C storage.

Trehalose in glycerol-free freezing extender enhances post-thaw survival of boar spermatozoa

Cryopreservation of boar semen is still considered suboptimal due to lower fertility as compared with fresh samples when glycerol, a permeating cryoprotectant, is used. Trehalose is a non-permeable cryoprotectant and nonreducing disaccharide known to stabilize proteins and biologic membranes. The aim of this study was to evaluate the cryosurvival and in vitro penetrability of boar spermatozoa when glycerol was replaced with trehalose in a freezing extender. Ejaculated Berkshire semen samples were diluted in egg yolk-based freezing extender containing glycerol (100 mM) or trehalose (0, 50, 100, 150, 200 and 250 mM) and cryopreserved using a straw freezing procedure. Thawed samples were analyzed for motility, viability, mitochondrial membrane potential (MMP), and acrosome integrity. In experiment 2, penetrability of spermatozoa cryopreserved with 100 mM glycerol or trehalose was examined. Replacement of cryoprotectant glycerol (100 mM) with trehalose had no effect on sperm viability, but replacing it with 100 mM trehalose improved motility, MMP and acrosome integrity significantly. Sperm motility and MMP were considerably higher in 100 mM trehalose, whereas the acrosome integrity was substantially higher in 100–250 mM trehalose. The in vitro penetration rate was also significantly higher in spermatozoa cryopreserved with trehalose (61.3%) than in those cryopreserved with glycerol (43.6%). In conclusion, 100 mM non-permeable trehalose can be used to replace glycerol, a permeating cryoprotectant, for maintenance of better post-thaw quality of boar spermatozoa.

Effect of different concentrations of trehalose and glycerol on the freezability of ram semen using soybean lecithin-based diluents

This study was conducted to determine the effect of different levels of trehalose and glycerol on ram sperm cryosurvival using lecithin-based diluents. Ejaculates were collected from four rams, pooled after initial evaluation, diluted with Tris-soybean lecithin extender and split into nine equal parts. A total of 0 (T0), 50 (T50) or 100 (T100) mM of trehalose and 3% (G3), 5% (G5) or 7% (G7) of glycerol were added to each part. Sperm motility, viability, plasma membrane integrity and acrosome integrity were evaluated immediately after thawing (0 h), and subsequently after 3 h and 6 h post-thawing incubation at 37°C. Results indicated that there was interaction between trehalose and glycerol on sperm motility. In addition, interaction of trehalose and glycerol with incubation time on sperm motility, viability, plasma membrane integrity and acrosome integrity was not significant (P > 0.05). Sperm motility was greatest in the sperm treated with 100 mM trehalose and 7% glycerol (27%; P < 0.05). The effect of trehalose was significant on viability and plasma membrane integrity of ram spermatozoa (P < 0.05). The main effect of trehalose showed that sperm viability was higher in T100 (47.06%) than T50 (53.96%; P < 0.05). The highest membrane integrity was observed in T100 (47.04%; P < 0.05). Membrane integrity was higher (P < 0.05) in G5 (49.97%) than G3 (41.56%) and there was no difference between G7 (46.86%) and G3 (41.56%; P > 0.05). The best sperm viability and plasma membrane integrity was observed at 0 h (65.75% and 51.58%, respectively). It was concluded that simultaneous use of 7% glycerol and 100 mM trehalose had a desirable effect on motility of ram frozen–thawed sperm.

Effect of metformin on the fertilizing ability of mouse spermatozoa

Numerous antioxidants have been added to cryopreservation media with varied success. The biguanide, metformin, commonly used for the treatment of type II diabetes, possesses properties impacting metabolism control that have not been yet assessed in cryopreservation protocols. The aim of this experiment was to; (i) determine the effect of metformin on fresh spermatozoa properties; and (ii) to assess positive or negative effects of metformin in post-thaw function and fertilizing capacity of mouse spermatozoa when used in cryopreservation media. The experiments have shown that the presence of metformin in fresh semen did not induce negative effects on spermatozoa quality, except a slight reduction in sperm motility at 5000μM metformin. However, when metformin was included in a cryopreservation protocol, an improvement in the fertilization rate and a reduction in the percentage of abnormal zygotes after in vitro fertilization was observed. In conclusion, metformin did not affect sperm quality at low concentrations (50μM), but its presence in the cryopreservation media could represent a benefit to improve the quality of frozen semen.

Effect of Addition of Taurine on the Liquid Storage (5°C) of Mithun (Bos frontalis) Semen

The present study was undertaken to assess the effect of taurine on sperm motility, viability, total sperm abnormalities, acrosomal and plasma membrane integrity, enzymatic profiles such as reduced glutathione (GSH), glutathione peroxidase (GPX), superoxide dismutase (SOD), and catalase (CAT), and biochemical profiles such as cholesterol efflux and malondialdehyde (MDA) production. A total of 50 ejaculates were collected twice a week from 8 mithun bulls, and semen was split into 4 equal aliquots and diluted with the TEYC extender. Group 1: semen was without additives (control); groups 2 to 4: semen was diluted with 25 mM, 50 mM, and 100 mM of taurine, respectively. Seminal parameters and enzymatic and biochemical profiles were assessed at 5°C. Inclusion of taurine into diluent resulted in significant (P < 0.05) decreases in percentages of dead spermatozoa, abnormal spermatozoa, and acrosomal abnormalities after liquid storage compared with the control group. Additionally, taurine at 50 mM has significant improvement in quality of mithun semen than taurine at 25 or 100 mM stored in in vitro at 5°C. It was concluded that the possible protective effects of taurine on sperm parameters are from enhancing the function of antioxidant enzymes, preventing efflux of cholesterol from cell membranes and decreased MDA production.

Trehalose and glycerol have a dose-dependent synergistic effect on the post-thawing quality of ram semen cryopreserved in a soybean lecithin-based extender

The objective of this study was to examine the interaction of different concentrations of trehalose [0 (T0), 50 (T50) or 100 (T100) mM] and glycerol [5% (G5) or 7% (G7)] on post-thawed quality of ram semen, cryopreserved in a soybean lecithin (SL)-based extender. Twenty-eight ejaculates were collected from four rams and diluted with six trehalose/glycerol combinations: T0G5, T50G5, T100G5, T0G7, T50G7, and T100G7. Sperm motility (CASA), membrane integrity (eosin/nigrosin) and functionality (HOST), abnormal forms, capacitation status (CTC), mitochondrial activity (rhodamine 123), apoptotic features (Annexin V/propidium iodide) and lipoperoxidation (malondialdehyde production) were evaluated after thawing. Extender T100G5 yielded the highest results for total and progressive motility, sperm velocity, normal morphology, functional membranes, active mitochondria and membrane integrity, with P<0.05 in general, except for T50G7 (P>0.05). The combinations T0G5, T0G7 and T100G7 yielded the lowest post-thaw quality. We could not detect significant changes in other kinematic parameters, capacitation status or lipoperoxidation. We conclude that, in our SL-based extender, a combination of 100 mM trehalose and 5% glycerol was the most adequate combination to achieving post-thawing quality in our soybean lecithin-based extender, and our results support that a synergistic effect among trehalose and glycerol exists. We suggest that other combinations could improve these results.