Resveratrol and Epigallocatechin-3-gallate addition to thawed boar sperm improves in vitro fertilization

Extracellular cAMP and MRP4 activity influence in vitro capacitation and fertilizing ability of pig spermatozoa

cAMP has been reported to be an essential driver of sperm capacitation. In bovine sperm cAMP efflux through multidrug resistance-associated protein 4 (MRP4) has been suggested to maintain intracellular cAMP homeostasis and generate extracellular signaling able to regulate capacitation. The aim of this work was to determine whether extracellular cAMP may influence in vitro pig sperm capacitation and acquisition of fertilizing ability and to evaluate the role of MRP4. In vitro sperm capacitation and gamete coincubation were performed in Brackett and Oliphant's medium (BO) in presence of caffeine (Ctr+) or in BO without caffeine (Ctr-) supplemented with 0, 8, 9, 10 mM cAMP. Despite the percentage of capacitated sperm, assayed by immunolocalization of tyrosine-phosphorylated proteins, was significantly lower in Ctr- compared to Ctr+, it increased supplementing 10 mM cAMP to Ctr- reaching values similar to Ctr+. The absence of caffeine during gamete coincubation reduced the fertilization rate compared to Ctr+, while 10 mM cAMP supplementation to Ctr- increased the fertilization rate reaching values similar to Ctr + . The presence of MRP4 in pig spermatozoa was detected for the first time by western blot and immunohistochemistry assays. To evaluate MRP4 role on pig sperm capacitation, in vitro capacitation and gamete coincubation were performed in Ctr + in presence of MK571, a MRP4 selective inhibitor. MK571 reduced the percentage of capacitated cells and the fertilization rate, while cAMP addition fully reversed MRP4 blockade consequences. Present findings suggest that, under our in vitro conditions, extracellular cAMP and MRP4 activity influence pig sperm capacitating events.

The emergence of natural products as potential therapeutics for male infertility

Infertility is a major reproductive health problem. Approximately 50% of all documented cases of infertility are attributable to male factors, such as poor testicular function and semen quality. The recent significant global decline in sperm counts has serious implications for male fertility, but the armamentarium for improving testicular function and semen quality is limited. Natural products have a wide range of activities and are a major source of drugs for disease prevention and treatment. To provide ideas and a theoretical basis for the research and development of therapeutic drugs for male infertility, this review summarizes natural products (mostly monomers) that have been shown to improve testicular function and semen quality and their possible mechanisms of action. These natural products primarily improve testicular function and semen quality via antioxidant, antiapoptotic, and anti-inflammatory effects, in addition to increasing serum testosterone and reducing DNA damage in spermatozoa and testicular cells. Prospects for the application of natural products in the treatment of male infertility are discussed.

Ameliorative effect of silymarin on the quality of frozen-thawed boar spermatozoa

Although Silymarin (SMN) has powerful antioxidant properties, little is known about its effects on the quality of frozen-thawed boar sperm. The present study aimed to evaluate the influences of SMN added to the thawing extender on boar sperm parameters essential for fertilization. The frozen-thawed semen was diluted in a Modena thawing extender supplemented with different concentrations of SMN (0, 5, 10, 20 and 50 μM respectively), and then the changes in quality parameters, antioxidant capacity, mitochondrial function and in vitro fertilization (IVF) capability of frozen-thawed sperm were assessed. Here we demonstrated that the motility, plasma membrane integrity and acrosomal integrity of frozen-thawed sperm improved efficiently by SMN (p < .05). In antioxidant parameters evaluation, the tROS level and MDA content of frozen-thawed spermatozoa were reduced in the 20 μM SMN group, while the T-AOC activity significantly increased (p < .05), indicating that the supplementation with SMN can promote the antioxidant capacity of frozen-thawed boar sperm. Besides, we also discovered that the addition of SMN significantly upregulated ATP content and enhanced the mitochondrial activity of sperm. More interestingly, SMN promoted the activities of mitochondrial respiratory chain complexes (MRCC) I, II, III and IV in frozen-thawed sperm significantly. Functionally, the higher penetration rate and increased total efficiency of fertilization were observed in the 20 μM SMN group. In summary, supplementation with SMN in the thawing medium ameliorates the quality of frozen-thawed boar sperm by enhancing mitochondrial respiratory capacity, producing large amounts of ATP and regulating ROS formation.

Coping with Oxidative Stress in Reproductive Pathophysiology and Assisted Reproduction: Melatonin as an Emerging Therapeutical Tool

Infertility is an increasing global public health concern with socio-psychological implications for affected couples. Remarkable advances in reproductive medicine have led to successful treatments such as assisted reproductive techniques (ART). However, the search for new therapeutic tools to improve ART success rates has become a research hotspot. In the last few years, pineal indolamine melatonin has been investigated for its powerful antioxidant properties and its role in reproductive physiology. It is considered a promising therapeutical agent to counteract the detrimental effects associated with oxidative stress in fertility treatments. The aim of the present narrative review was to summarize the current state of the art on the importance of melatonin in reproductive physiology and to provide a critical evaluation of the data available encompassing basic, translational and clinical studies on its potential use in ART to improve fertility success rates.

Optimization of the Thawing Protocol for Iberian Boar Sperm

Simple Summary

Limited attention is paid to sperm thawing protocols, and their study could be relevant to endangered species or breeds, especially for cryopreserved material present in the existing gene banks. The aim of this study was to determine the most optimal thawing protocol for Iberian boar sperm through testing different thawing rates and different modifications of the thawing extender. Based on the findings, the most optimal results were obtained thawing at 70 °C for 8 s with the inclusion of cyclodextrins loaded with cholesterol (CLC) in the extender, revealing the importance of adapting the thawing protocols.

Abstract

Thawing protocols have been barely studied, and their modifications may lead to a substantial improvement in post-thawing sperm quality, which could be of great relevance to existing sperm banks, such as those for Iberian pig breeds with varieties in danger of extinction. For that, the study aimed to evaluate different thawing rates and to evaluate modifications in the composition of the thawing extender (basic pH to 8–8.2, incorporation of cyclodextrins loaded with cholesterol [CLC] and the incorporation of ion chelators [EDTA and EGTA]). After thawing, overall sperm motility and kinematic parameters, acrosome status and sperm membrane integrity were evaluated. The most optimal results were obtained with the thawing rate reaching 70 °C for 8 s with the inclusion of 12.5 mg of CLC/500 × 10⁶ spermatozoa in the thawing extender, which showed an improvement compared to the control at 70 °C. In conclusion, to adapt the thawing conditions may be relevant, especially for endangered species or breeds such as some varieties of Iberian pig, since this process could also be used in samples cryopreserved in gene banks.

Association between tea consumption and semen quality among 1385 healthy Chinese men

Information on the association between tea drinking and semen quality is limited. Little is reported on whether tea drinking is benefit to sperm quality. This cross-sectional and longitudinal study was conducted between April 2017 and July 2018. Participants were healthy men who were screened as potential sperm donors recruited at the Hubei Province Human Sperm Bank of China. A structured questionnaires containing sociodemographic information, daily habits, sperm collection-related information was completed for each participant at interview. Repeated semen samples were taken to examine the sperm parameters, including sperm volume, sperm concentration, sperm count, progressive motility, and total motility. A total of 1385 men with 6466 sperm samples were included in this study. Two groups were compared: tea drinking men (389, 28.1%) and non-tea drinking men (996, 71.9%). Compared with subjects who never drink tea, the analyses showed that sperm concentration and total sperm count were higher in tea-consuming subjects. A 10-year period or more duration of tea drinking significantly increased semen concentrations by 16.27% (P < 0.05). Sperm concentration was increased in subjects with a frequency of tea drinking of 3 days or more per week (P < 0.05) or, among men who were occasional alcohol drinkers, when tea concentration was weak (P < 0.05). No evidence of trend effects (P for trend > 0.05) or interaction effects (P for interaction > 0.05) between tea consumption and sperm quality, respectively. Our findings provide evidence that tea drinking may improve male reproductive health. Long-term, frequent, weak tea drinking tends to increase sperm quality among men with low BMI or health-related behaviors like smoking or alcohol intake.

Tea and coffee polyphenols and their biological properties based on the latest in vitro investigations

Tea and coffee contain numerous polyphenolic compounds that exhibit health-promoting properties for humans, including antioxidant and neuroprotective properties, and can also take part in the treatment of covid-19 and improve fertility. This review, presents the activity of polyphenols found in different types of tea and coffee and describes the effects of tea fermentation and coffee roasting on their polyphenol composition and antioxidant properties. Polyphenol oxidase activity is reduced in the fermentation process; therefore black tea contains significantly less polyphenolic compounds compared to green and white tea. Epigallocatechin-3-gallate - a polyphenol from tea - effectively has been shown to inhibit the activity of SARS-CoV-2 as it blocked binding of coronavirus 2 to human angiotensin converting enzyme 2, decreased the expression of inflammatory factors in the blood, including tumor necrosis factor-α and interleukin-6, and significantly increased the overall fertilization efficiency in animals. Coffee roasting process influences both the content of polyphenols and the oxidative activity. The lowest levels of active compounds such as caffeine, chlorogenic acid and coffee acids are identified in roasted coffee beans. On the other hand, light coffee and green coffee show the strongest cytotoxic potential and antioxidant properties, and thus the greatest ability to decrease apoptosis by stopping the cell cycle in the S phase. Proteins, such as components of milk, can strongly bind/interact with phenolic compounds (especially, the CGAs) contain in coffee, which may explain the negative influence of milk on its antioxidant properties. Coffee polyphenols have also antiproliferative and antiesterase activities, which may be important in prevention of cancer and neurodegenerative disorders, respectively. In this review, biological properties of tea and coffee polyphenols, observed mainly in in vitro studies have been described. Based on these findings, future directions of the research works on these compounds have been suggested.

Tea and coffee polyphenols and their biological properties based on the latest in vitro investigations

Tea and coffee contain numerous polyphenolic compounds that exhibit health-promoting properties for humans, including antioxidant and neuroprotective properties, and can also take part in the treatment of covid-19 and improve fertility. This review, presents the activity of polyphenols found in different types of tea and coffee and describes the effects of tea fermentation and coffee roasting on their polyphenol composition and antioxidant properties. Polyphenol oxidase activity is reduced in the fermentation process; therefore black tea contains significantly less polyphenolic compounds compared to green and white tea. Epigallocatechin-3-gallate - a polyphenol from tea - effectively has been shown to inhibit the activity of SARS-CoV-2 as it blocked binding of coronavirus 2 to human angiotensin converting enzyme 2, decreased the expression of inflammatory factors in the blood, including tumor necrosis factor-α and interleukin-6, and significantly increased the overall fertilization efficiency in animals. Coffee roasting process influences both the content of polyphenols and the oxidative activity. The lowest levels of active compounds such as caffeine, chlorogenic acid and coffee acids are identified in roasted coffee beans. On the other hand, light coffee and green coffee show the strongest cytotoxic potential and antioxidant properties, and thus the greatest ability to decrease apoptosis by stopping the cell cycle in the S phase. Proteins, such as components of milk, can strongly bind/interact with phenolic compounds (especially, the CGAs) contain in coffee, which may explain the negative influence of milk on its antioxidant properties. Coffee polyphenols have also antiproliferative and antiesterase activities, which may be important in prevention of cancer and neurodegenerative disorders, respectively. In this review, biological properties of tea and coffee polyphenols, observed mainly in in vitro studies have been described. Based on these findings, future directions of the research works on these compounds have been suggested.

Epigallocatechin 3-gallate improves the quality of bull semen cryopreservation

To determine the effects of epigallocatechin-3-gallate (EGCG) on the cryopreservation of bovine semen, epigallocatechin-3-gallate dissolved with double distilled water to 0.2, 0.4, 0.6 and 0.8 mg/ml were added to the cryopreservation diluent of the bull semen. Then, we used computer-assisted analysis of semen kinematic parameters, staining method to detect membrane function, acrosome integrity, enzyme-linked immunosorbent assay to detect catalase (CAT), superoxide dismutase (SOD), glutathione peroxidase (GSH-Px), malondialdehydes (MDA) and reactive oxygen levels. The results showed that adding 0.6 mg/L of epigallocatechin-3-gallate could improve the cryopreserved sperm quality, which significantly increased the total motility, distance average path, distance straight line, distance curved line, average path velocity, curvilinear-velocity, straight-line velocity, amplitude of lateral head displacement and beat/cross frequency, as well as sperm CAT, GSH-Px and SOD levels (p < 0.05), whilst reducing the reactive oxygen species and MDA levels (p < 0.05). Hence, these results indicate that the addition of 0.6 mg/ml of EGCG has a protective effect on the cryopreservation of the bovine semen.

Role of exogenous antioxidants on the performance and function of pig sperm after preservation in liquid and frozen states: A systematic review

In situations where an excessive generation of reactive oxygen species overwhelms antioxidant capacity, a harmful effect on sperm function is exerted. Antioxidants are molecules capable of minimizing this detrimental effect, which is important in pig sperm due to the high content of polyunsaturated fatty acids in their plasma membrane. The present systematic review aims at evaluating whether supplementing semen extenders (for liquid storage at 17 °C) or freezing and/or thawing media (for cryopreservation) with antioxidants influences sperm quality and functionality parameters, and in vitro/in vivo fertility outcomes. We defined inclusion and exclusion criteria in a PICOS table according to PRISMA guidelines, and conducted a literature search through MEDLINE-PubMed in November 2020. After systematic selection, 75 studies were included: 47 focused on cryopreservation and 28 on liquid storage at 17 °C. More than 70% of the studies included in this review showed that adding semen extenders for liquid storage and/or freezing/thawing media for cryopreservation with antioxidants enhances sperm quality and functionality parameters. In addition, this supplementation improves in vivo/in vitro fertility outcomes, supporting the hypothesis that the beneficial effect observed upon sperm quality has a positive impact on reproduction outcomes.

Nanocarried antioxidants in freezing extenders for boar spermatozoa

Post-thawing cryoinjuries in boar spermatozoa due to oxidative stress may be reduced by adding nanoencapsulated antioxidants to freezing extenders. This study evaluated post-thawing kinetics, structural and biochemical functions of boar spermatozoa frozen with extenders including resveratrol and vitamin E loaded into polymeric nanocapsules. Resveratrol was added at 0 (control), 5, 10, 20, 40 and 80 µg/ml, whereas Vitamin E was added at 0 (control), 50, 100, 200 and 400 µg/ml. Both antioxidants were tested in free and nanoencapsulated presentations. In contact with empty nanocapsules, some sperm kinetics parameters were impaired compared to the control (p < .05), whereas lipoperoxidation declined (p < .05). With inclusion of 40 µg/ml nanoencapsulated resveratrol, some sperm kinetics parameters were improved (p < .01), but sperm motility, structural and biochemical functions did not differ from the control (p > .05). No improvement in sperm quality occurred with inclusion of vitamin E, although sperm kinetics with 400 µg/ml nanoencapsulated vitamin E was reduced compared to the control (p < .01). Inclusion of 40 µg/ml nanoencapsulated resveratrol benefitted boar sperm kinetics after thawing, but no improvement resulted from inclusion of vitamin E.

Impact of Polyphenolic-Food on Longevity: An Elixir of Life. An Overview

Aging and, particularly, the onset of age-related diseases are associated with tissue dysfunction and macromolecular damage, some of which can be attributed to accumulation of oxidative damage. Recently, growing interest has emerged on the beneficial effects of plant-based diets for the prevention of chronic diseases including obesity, diabetes, and cardiovascular disease. Several studies collectively suggests that the intake of polyphenols and their major food sources may exert beneficial effects on improving insulin resistance and related diabetes risk factors, such as inflammation and oxidative stress. They are the most abundant antioxidants in the diet, and their intake has been associated with a reduced aging in humans. Polyphenolic intake has been shown to be effective at ameliorating several age-related phenotypes, including oxidative stress, inflammation, impaired proteostasis, and cellular senescence, both in vitro and in vivo. In this paper, effects of these phytochemicals (either pure forms or polyphenolic-food) are reviewed and summarized according to affected cellular signaling pathways. Finally, the effectiveness of the anti-aging preventive action of nutritional interventions based on diets rich in polyphenolic food, such as the diets of the Blue zones, are discussed.

The use of resveratrol decreases liquid-extend boar semen fertility, even in concentrations that do not alter semen quality

In vitro and in vivo assays were conducted to investigate the effects of trans-resveratrol (RVT) on liquid-extended boar semen during 72 h of storage at 17 °C. Thirty-six ejaculates were collected from six boars, evaluated, and extended. RVT was then added at the indicated treatment concentration (0, 0.01, 0.1 or 1 mM), and the ejaculates were cooled to 17 °C and evaluated at 0, 24, 48, and 72 h. Samples were evaluated for sperm motility, kinetics, plasma and acrosome integrity, mitochondrial membrane potential, anion superoxide levels, lipoperoxidation, and antioxidant enzyme activity. In the follow-up experiment, twenty-eight gilts were fixed-time inseminated with 0 or 0.01 mM RVT liquid-extended boar semen. After five days, they were slaughtered, and their reproductive tracts were recovered. The embryos were collected, and the pregnancy, fertility, and viable embryo rates were calculated. In the in vitro assays, total motility, plasma and acrosome membrane integrity, mitochondrial membrane potential, anion superoxide levels, and lipoperoxidation did not change at any of the evaluation times with the use of RVT up to 0.01 mM. RVT decreased SOD activity without changes in GPx. RVT used at 1 mM showed harmful effects for almost all evaluated parameters. For the in vivo assay, the same pregnancy and fertility rates were observed for both groups, while the viable embryo rate was three-fold lower in the 0.01 mM group than in the 0 mM group. The results showed a dichotomous effect of RVT; a low concentration was not harmful in vitro but was catastrophic for embryo viability.

Epigallocatechin-3-Gallate Promotes the in vitro Maturation and Embryo Development Following IVF of Porcine Oocytes

Purpose

Epigallocatechin-3-gallate (EGCG) is a major ingredient of catechin polyphenols and exerts protective effects because of its strong antioxidant properties. As far as we know, there is still a lack of systematic research on the effects of EGCG on the in vitro maturation (IVM) and in vitro fertilization (IVF) of porcine oocytes. The present study aimed to determine the effects of EGCG on the IVM and IVF of porcine oocytes.

Methods

Porcine oocytes were treated with different concentrations of EGCG (5, 10 and 20 µM), and the cumulus cell expansion, oocyte maturation rate, reactive oxygen species (ROS), glutathione (GSH) and malondialdehyde (MDA) levels, total antioxidant capacity were determined. The mRNA expression levels of oxidative stress- and apoptosis-associated genes were determined by quantitative real-time PCR. The cleavage rate and blastocyst rate of oocytes after 10 μM EGCG treatment during IVM and IVF were also evaluated.

Results

EGCG at 5, 10 and 20 μM significantly promoted cumulus cell expansion, and EGCG at 10 μM increased the oocyte maturation rate. EGCG (10 μM) treatment reduced the ROS and MDA levels, while increased the antioxidant capacity and GSH concentrations in the mature oocytes. The qRT-PCR results showed that EGCG treatment up-regulated the mRNA expression of catalase, glutathione peroxidase and superoxide dismutase in the mature oocytes. In addition, EGCG treatment also decreased the mRNA expression levels of Bax and caspase-3 and increased the Bcl-2 mRNA expression level in the mature oocytes. In addition, the cleavage rate and blastocyst rate of oocytes treated with 10 μM EGCG during IVM and IVF were significantly higher than those of the control group.

Conclusion

Our results suggest that EGCG promotes the in vitro maturation and embryo development following IVF of porcine oocytes. The protective effects of EGCG on the oocytes may be associated with its antioxidant and anti-apoptosis properties.

The inhibition of spermatic cystine/glutamate antiporter xCT (SLC7A11) influences the ability of cryopreserved stallion sperm to bind to heterologous zonae pellucidae

Sperm are redox-regulated cells, and deregulation of their redox status is considered to affect male fertility and to reduce their fertilizing ability following biotechnological procedures, such as cryopreservation. Cystine (CysS), after incorporation in sperm via SLC7A11 antiporter, has been demonstrated to increase intracellular GSH content, the most important non enzymatic antioxidant. This study was aimed at investigating the role of SLC7A11 antiporter on frozen-thawed stallion sperm ability to respond to in vitro capacitating environment after post-thaw incubation with CysS and/or Sulfasalazine (SS), a specific inhibitor of SLC7A11 antiporter. Viability, motility, immunolocalization of tyrosine phosphorylated proteins and the ability to bind to heterologous zonae pellucidae were evaluated. Thawed sperm from seven stallions (2 ejaculates/stallion) was washed and resuspended in Tyrodes media; each thawed ejaculate was divided in Control (CTR) and 3 samples supplemented with: 0.5 mM Cystine (CysS), 500 μM Sulfasalazine (SS) and 0.5 mM CysS + 500 μM SS (CysS + SS). After 1 h of incubation at 37 °C, samples were washed twice, resuspended in capacitating BWW medium and incubated at 38 °C under 5% CO₂. After 30 and 60 min, sperm motility, viability and tyrosine phosphorylated protein immunolocalization, used as capacitation status index, were evaluated. After 30 min of capacitation, 4 × 10⁵ sperm were co-incubated with denuded pig oocytes in capacitation medium for 30 min for the heterologous binding assay. None of the sperm parameters studied (motility, viability and tyrosine phosphorylation) showed any difference respective to control. The number of sperm bound per oocyte (mean ± SEM) tended to increase in CysS group (44.0 ± 12.3) respect CTR (40.8 ± 10.8) while decreased in SS group (32.4 ± 7.8) (p < 0.01). Moreover, CysS + SS group showed a lower binding rate (32.0 ± 10.0) compared to CysS (p < 0.001). Our results suggest that CysS supplementation of thawed stallion sperm can influence their ability to bind to heterologous zona pellucidae as the inhibition of CysS incorporation by SLC7A11 reduced the number of sperm bound per oocyte. This effect does not seem to be ascribed to a modification of sperm motility, membrane integrity and tyrosine phosphorylation.

Multiparametric Study of Antioxidant Effect on Ram Sperm Cryopreservation-From Field Trials to Research Bench

Simple Summary

The use of antioxidant compounds could be a successful tool to improve sperm cryopreservation protocols in ovine species. These molecules have been widely employed in different mammalian species with this purpose. It is important to consider the existence of a species-specific antioxidant effect discarding the extrapolations from other animal species. To corroborate the real effectiveness of these compounds is important to combine two approaches: in vitro sperm quality analyses and in vivo field trials based on fertility. In the first scenario, a multiparametric analyses and novel tests based on spermatozoa redox balance, as the main target of antioxidants, could improve the accuracy on antioxidant effectiveness on sperm quality. Moreover, an extensive field insemination study provides the definitive tool to select the best antioxidant treatment. All these aspects have been applied and extensively discussed throughout this manuscript. Novel approaches have been incorporated, such as RedoxSYS, to provide more accuracy in the integrative studies of Redox status in spermatozoa. The effectiveness of an antioxidant treatment, as trolox in our study, should be demonstrated in an integrative way, from in vivo (fertility trials) to in vitro analyses (sperm quality assays), especially when the final aim is to reach AI implementation.

Abstract

The optimization of sperm cryopreservation protocols in ram is a feasible tool to reinforce artificial insemination technologies considering the desirable application of sperm by vaginal/cervical or transcervical deposition. Cryopreservation provokes different types of damage on spermatozoa and many of these detrimental effects are triggered by redox deregulation. For this reason, the antioxidant supplementation in sperm cryopreservation protocols to decrease reactive oxygen species (ROS) levels and to equilibrate redox status has been widely employed in different species. Despite this, more fertility trials are necessary to provide the definitive tool to ensure the antioxidant effectiveness on sperm quality. For this reason, in this work, we performed a multiparametric analysis of some previously tested antioxidants (crocin, GSH and Trolox) on ram sperm cryopreservation from field trials to sperm quality analyses focused on new strategies to measure redox balance. Attending to fertility trial, Trolox supplementation registered an improvement concerning to fertility (when we considered high fertility males) and multiple lambing frequency and other complementary and descriptive data related to lambing performance such as prolificacy and fecundity. This positive effect was more evident in multiple lambing frequency when we considered low fertility males than in global male analysis. In vitro analyses of sperm quality confirmed in vivo trials registering a positive effect on sperm viability and redox balance. In this study, we provided the definitive evidence that the role of trolox on redox balance maintenance has a direct effect on fertility parameters, such as prolificacy. The effectiveness of antioxidant treatments was tested, for the first time in ovine species, using an integrative and multiparametric approach combining in vivo and in vitro analyses and novel approaches, such as RedoxSYS. These types of strategies should be applied to improve sperm conservation methods and optimize AI technologies upgrading the correlation between in vitro and in vivo analyses.

Polyphenols in Farm Animals: Source of Reproductive Gain or Waste?

Reproduction is a complex process that is substantially affected by environmental cues, specifically feed/diet and its components. Farm animals as herbivorous animals are exposed to a large amount of polyphenols present in their natural feeding system, in alternative feed resources (shrubs, trees, and agro-industrial byproducts), and in polyphenol-enriched additives. Such exposure has increased because of the well-known antioxidant properties of polyphenols. However, to date, the argumentation around the impacts of polyphenols on reproductive events is debatable. Accordingly, the intensive inclusion of polyphenols in the diets of breeding animals and in media for assisted reproductive techniques needs further investigation, avoiding any source of reproductive waste and achieving maximum benefits. This review illustrates recent findings connecting dietary polyphenols consumption from different sources (conventional and unconventional feeds) with the reproductive performance of farm animals, underpinned by the findings of in vitro studies in this field. This update will help in formulating proper diets, optimizing the introduction of new plant species, and feed additives for improving reproductive function, avoiding possible reproductive wastes and maximizing possible benefits.

Melatonin regulates ATP content and fertilising capacity of Onychostoma macrolepis spermatozoa by inhibiting ROS accumulation during semen storage in vitro

Melatonin (MLT) is an efficient antioxidant that protects spermatozoa against damages caused by oxidative stress. In this study, to maintain good function of Onychostoma macrolepis spermatozoa during semen preservation invitro at 4°C, different concentrations of MLT (0.5, 1 and 2μM) were added to the semen. After storage (0, 24, 48 and 72h), 1μM MLT in semen markedly improved sperm quality, as reflected by better plasma membrane integrity, the relative steady level of reactive oxygen species (ROS) and slower rate of decrease in mitochondrial membrane potential. Activated spermatozoa in semen with 1μM MLT had higher kinematic performance (i.e. percentage of motile and progressive spermatozoa and the beat cross frequency; P<0.05) and longer duration of sperm motility (P<0.05) compared with spermatozoa in semen withother MLT concentrations. Furthermore, 1μM MLT maintained higher ATP concentrations in spermatozoa during semen storage and significantly improved the fertilising capacity of spermatozoa after 72h semen storage compared with the other MLT concentrations. To expand wild resources of O. macrolepis, 1μM MLT can be used as a semen additive to maintain better sperm function and enhance sperm fertilising capacity in artificial insemination (AI).

Effect of MnTBAP on in vitro capacitation of frozen-thawed stallion sperm

In vitro manipulation of spermatozoa leads to deleterious changes of structure and function that occur mainly due to oxidative stress, therefore, prevention or treatment is a strategy to improve the functions of processed sperm. In the present study, the aim was to evaluate the effects of MnTBAP supplementation, a compound with antioxidant activity, on in vitro capacitation conditions of thawed equine sperm. For this purpose, stallion spermatozoa (2 × 10⁶ cells/mL) were incubated in the sperm-TLP base medium for 4 h in which there were three different conditions: non-capacitating, capacitating, and capacitating plus 150 mM MnTBAP. There were incubations for 4 h at 37.5 °C in a humidified air atmosphere. Sample analysis was performed immediately after thawing (0 h), and at the end of the incubation period (4 h), unless otherwise indicated. The following variables were evaluated for spermatozoa: plasma membrane integrity and fluidity, acrosome integrity, intracellular calcium concentrations, intracellular pH, tyrosine phosphorylation, ATP concentrations, motility and heterologous zona-binding assay, using flow cytometry, fluorescent microscopy and/or chemiluminescence, depending on the most appropriate procedure for the variable being evaluated. Results indicated that capacitation-like changes were synergistically induced by the cAMP agonists, phosphodiesterase inhibitor and bicarbonate. The presence of bovine serum albumin was harmful to the plasma membrane. The MnTBAP supplementation had a positive effect on viability-related markers (plasma membrane integrity, membrane fluidity, associated with greater intracellular pH) when there were capacitating conditions. In conclusion, the activity of MnTBAP contributes to improving the in vitro incubation conditions of frozen-thawed stallion sperm.

Cyanidin improves oocyte maturation and the in vitro production of pig embryos

The objective of this study was to reduce the negative effects of oxidative stress by decreasing the levels of reactive oxygen species (ROS) through supplementation of the major antioxidants present in elderberries: kuromanin and cyanidin. Oocytes (n = 1150) were supplemented with 100 or 200 μM of kuromanin or cyanidin during maturation, and then evaluated for ROS levels or fertilized and evaluated for penetration, polyspermic penetration, male pronucleus formation, and embryonic development. The ROS levels and incidence of polyspermic penetration were lower (P < 0.05) in oocytes supplemented with 100 μM cyanidin when compared with other treatments. Supplementation of 100 μM cyanidin increased (P < 0.05) MPN and blastocyst formation compared with other treatments. However, supplementation of 100 μM kuromanin did not have significant effects on the criteria evaluated, and supplementation of 200 μM kuromanin had significant (P < 0.05) detrimental effects for each criterion. Additional oocytes (n = 1438) were supplemented with 100 μM cyanidin during maturation and evaluated for glutathione, glutathione peroxidase, catalase, and superoxide dismutase activity. Supplementation of 100 μM cyanidin increased (P < 0.05) catalase activity and intracellular GSH levels compared with no supplementation of cyanidin. These results indicate that supplementing cyanidin during maturation reduces oxidative stress by reducing ROS levels and increasing GSH concentrations within the oocyte.

Resveratrol protects boar sperm in vitro via its antioxidant capacity

The objective of the present study was to elucidate whether resveratrol could facilitate the survival of boar sperm during liquid preservation and fast cooling processes. Boar semen were diluted with Modena extender containing different concentrations of resveratrol. Sperm motility was evaluated by visual estimation. Membrane integrity, acrosome integrity and mitochondrial membrane potentials were measured by SYBR-14/PI, FITC-PNA and JC-1 staining, respectively. Moreover, the levels of reactive oxygen species (ROS), malonaldehyde (MDA) and total antioxidant capacity (T-AOC) were measured using commercial assay kits. B-cell lymphoma protein-2 (BCL2) content was determined by western blotting. During liquid preservation at 17oC, the addition of 50 μM resveratrol to the Modena extender significantly improved sperm motility, membrane integrity, acrosome integrity, and sperm mitochondrial membrane potentials. Similar results were also observed in the 150 μM resveratrol group during the fast cooling process. Furthermore, addition of resveratrol led to a decrease of ROS and MDA, and an increase in the content of T-AOC and BCL2. These observations suggest that addition of resveratrol to Modena extender protects boar sperm against oxidative stress. The optimal concentrations of resveratrol are 50 μM and 150 μM during liquid preservation and fast cooling process, respectively.

Different approaches for assessing sperm function

Different approaches can be used to assess sperm function in different conditions, i.e. sperm storage, freezing-thawing or activation by induction of capacitation and acrosome reaction. In this review we will focus on the assays routinely performed in our laboratories, giving a literature support to critically analyse different approaches. In fact, researchers usually tend to look for the "one shot" parameter that could explain itself a specific process; it is our conviction that a multiparametric approach is still more valid, as some changes in sperm function are very complex and could be explained only by operating in different ways. Sperm motility, the most evident sperm characteristic, should be assessed by computer-aided sperm analysers that permit an objective evaluation of the motility and its kinematic parameters. Commercial and open source instruments are available and could be profitably used together with specific statistical approaches. The use of microscopy, and particularly fluorescent microscopy, could be a very useful tool to assess different parameters in sperm cells both by fluorophores that give indication of a determined function, and by immunolocalization of proteins, that permits the discover of new features or to explain particular sperm functions. The same substrates could be used also in flow cytometry: the difference is that it permits to study wider sperm populations (and their sub-population distribution). Flow cytometry is undergoing a very wide use in spermatology and technical and experimental rigor is needed to obtain reliable results. Metabolic assessment of sperm features, particularly energetic supply, ATP formation and other enzyme activities, could represent a very important challenge to acquire new information and complete/integrate those derived from other techniques. Finally, functional assays such as oocyte binding and in vitro fertilization, represent a very strong tool to assess sperm function in vitro, as they could evidence the functional intactness of some pathways.

Improvement of in vitro fertilization by a tannin rich vegetal extract addition to frozen thawed boar sperm

Boar spermatozoa are very susceptible to cryopreservation injuries and, for this reason, pig remains one of the few species in which fresh semen is still preferred to thawed one for routine artificial insemination (AI). The present work evaluated the effect of supplementing boar sperm thawing medium with Silvafeed SP (SSP), a mixture of Chestnut and Quebracho wood extracts (60/40 w/w) rich in polyphenols (92.4% tannin content) on in vitro fertilization (IVF) and on the following sperm parameters: sperm motility (assessed by CASA), viability, acrosome integrity, mitochondrial function and lipid peroxidation (assessed by flow cytometry) and capacitation status (immunolocalization of tyrosine phosphorylated proteins). Thawed spermatozoa were incubated 1 h at 37°C in BTS without (CTR) or with (5, 10, 20 µg/mL) SSP. After incubation sperm suspension was divided in three aliquots: one was used for IVF trials, one for sperm analysis, and the last one was capacitated for 1 h at 39°C 5% CO2 in IVF medium. Sperm motility parameters, viability, acrosome integrity, mitochondrial functionality, lipid peroxidation and tyrosine phosphorylated protein immunolocalization, used as capacitation parameter, were not influenced by SSP. However, oocytes inseminated with thawed spermatozoa pretreated with all the different SSP concentrations presented a significant (P < 0.01) increase in penetration rate compared to CTR. In addition, 5 µg/mL SSP exerted a positive effect (P<0.05) on the total efficiency of fertilization. These results encourage the use of SSP in the thawing medium since post-thawing fertility is a limit for the large-scale use of boar frozen semen.

Effect of different concentrations of resveratrol on the quality and in vitro fertilizing ability of ram semen stored at 5 °C for up to 168 h

The aim of the study was to investigate the effects of different concentrations of resveratrol on head morphology, motility characteristics, oxidative state and in vitro fertility of cooled ram spermatozoa. Pooled semen from three Najdi rams was diluted with Triladyl® having different concentrations of resveratrol, zero (control), 200 μM (45.65 μg/mL) and 400 μM (91.30 μg/mL) resveratrol, then stored at 5 °C for 168 h. The head morphometric, sperm kinematic parameters, Malondialdehyde (MDA), reduced glutathione (GSH), superoxide dismutase (SOD) and in vitro fertilizing capability of ram spermatozoa were evaluated after 24, 72, 120 and 168 h of cooling storage. The total motility (TM) of the sperm with resveratrol at 200 μM and 400 μM was significantly (p ≤ 0.05) higher than that in the control group at 72 and 120 h of cooling storage. On the other hand, the progressive motility (PM) of the sperm with resveratrol at 200 μM and 400 μM was significantly (p ≤ 0.05) higher than that in the control group at 168 h of cooling storage period. After 168 h of cooling storage, significantly higher straightness (STR) was observed in 400 μM group than two other groups and in 200 μM group than the control group. Both resveratrol groups had higher linearity (LIN) than control one at 120 and 168 h of cooling storage. The length, width and area of sperm head were lower (P ≤ 0.05) in the control compared to the other treatment groups after 120 and 168 h of storage. There was a significant increase in superoxide dismutase (SOD) concentration in the two resveratrol groups compared with the control one over the seven days of cooling storage and the same result was found in the reduced glutathione (GSH) concentration at 24, 72, and 168 h of storage. There was a significant (p ≤ 0.05) decrease in malondialdehyde (MDA) concentration in the 400 μM resveratrol group than that in two other groups over the seven days of storage period. Cleavage and blastocyst rates following in vitro fertilization were significantly higher (p ≤ 0.05) in 400 μM resveratrol than other groups at 72 h for cooling storage period. In conclusion, addition of resveratrol in the extender can protect sperm head morphology, improve kinematic parameters and in vitro fertility, and reduce oxidative stress of ram spermatozoa during liquid storage at 5 °C.

A Comprehensive Insight on the Health Benefits and Phytoconstituents of Camellia sinensis and Recent Approaches for Its Quality Control

Tea, Camellia sinensis, which belongs to the family Theaceae, is a shrub or evergreen tree up to 16 m in height. Green tea is very popular because of its marked health benefits comprising its anticancer, anti-oxidant, and antimicrobial activities, as well as its effectiveness in reducing body weight. Additionally, it was recognized by Chinese people as an effective traditional drink required for the prophylaxis against many health ailments. This is due to the complex chemical composition of green tea, which comprises different classes of chemical compounds, such as polyphenols, alkaloids, proteins, minerals, vitamins, amino acids, and others. The beneficial health effects of green tea ultimately led to its great consumption and increase its liability to be adulterated by either low-quality or non-green tea products with concomitant decrease in activity. Thus, in this review, green tea was selected to highlight its health benefits and phytoconstituents, as well as recent approaches for its quality-control monitoring that guarantee its incorporation in many pharmaceutical industries. More research is needed to find out other more biological activities, active constituents, and other simple and cheap techniques for its quality assurance that ascertain the prevention of its adulteration.

Resveratrol Improves Boar Sperm Quality via 5'AMP-Activated Protein Kinase Activation during Cryopreservation

Mammalian sperm is highly susceptible to the reactive oxygen species (ROS) stress caused by biochemical and physical modifications during the cryopreservation process. 5′AMP-activated protein kinase (AMPK) is involved in regulating both cell metabolism and cellular redox status. The aim of the present study was to investigate whether the resveratrol protects boar sperm against ROS stress via activation of AMPK during cryopreservation. Boar sperm was diluted with the freezing medium supplemented with resveratrol at different concentrations (0, 25, 50, 75, 100, and 125 μM). It was observed that the addition of 50 μM resveratrol significantly improved the postthaw sperm progressive motility, membrane integrity, acrosome integrity, mitochondrial activity, glutathione (GSH) level, activities of enzymatic antioxidants (glutathione peroxidase (GPx), superoxide dismutase (SOD), and catalase), and the phosphorylation of AMPK. Meanwhile, the lipid peroxidation, ROS levels, and apoptosis of postthaw sperm were reduced in the presence of 50 μM resveratrol. Furthermore, when fresh boar sperm was incubated with the medium in the presence of 50 μM resveratrol and 30 μM Compound C (an AMPK inhibitor), the effects of the resveratrol were partly counteracted by the Compound C. These observations suggest that the resveratrol protects boar sperm via promoting AMPK phosphorylation. In conclusion, the addition of resveratrol to the freezing extenders protects boar sperm against ROS damage via promoting AMPK phosphorylation for decreasing the ROS production and improving the antioxidative defense system of postthaw sperm. These findings provide novel insights into understanding the mechanisms of resveratrol on how to protect boar sperm quality contrary to the ROS production during cryopreservation.

Improving the quality of cryopreserved goat semen with a commercial bull extender supplemented with resveratrol

The purpose of the current study was to evaluate the effects of resveratrol (RSV) on the quality of frozen-thawed goat sperm. Semen samples from four bucks were divided into five aliquots and diluted with a commercial bull semen extender containing: no antioxidant (RSV-0, control), 10 μM RSV (RSV-10), 50 μM RSV (RSV-50), 100 μM RSV (RSV-100) and 250 μM RSV (RSV-250). After thawing, sperm motility, abnormal morphology, membrane and acrosome integrity, mitochondrial activity, phosphatidylserine (PS) distribution, and oxidative stress were evaluated. The results indicated that in comparison with the control, when the concentration of RSV was 10 or 50 μM, the total motility, progressive motility, membrane and acrosome integrity, and mitochondrial activity of post-thaw spermatozoa was greater (P < 0.05). Additionally, the use of extenders containing RSV-10 or RSV-50 resulted in a greater percentage of viable spermatozoa as compared to the other groups (P < 0.05). Importantly, there were more viable spermatozoa (49.61 ± 0.61%) and less non-viable spermatozoa (49.16 ± 1.01%) in the RSV-50 group compared to the other extenders (P < 0.05). Furthermore, the use of the extenders containing RSV-10 and -50 resulted in a reduction in ROS production in frozen-thawed spermatozoa as compared to the control (P < 0.05). There, however, was no difference among extenders for abnormal morphology and PS distribution. In conclusion, supplementation with RSV, at a concentration of 10 or 50 μM in the semen extender, can improve the post-thaw goat sperm quality, which may occur as a consequence of inhibition of ROS generation.

Resveratrol addition to in vitro maturation and in vitro culture media enhances developmental competence of sheep embryos

The present study aimed to examine the effects of adding different concentrations of resveratrol during in vitro culture (IVC) alone and during both in vitro maturation (IVM) and IVC on ovine blastocyst yield and quality. Therefore, this study was conducted in two separate experiments. The first experiment was carried out to test the effect of different concentrations of resveratrol (0, 0.1, 0.25, 0.5, 2.0, and 5.0 μM) in the IVC medium on cleavage, morula, developmental potential of blastocyst, and total cell number (TCN) of the embryos. Addition of 0.25 and 0.5 μM of resveratrol during IVC significantly enhanced morula and blastocyst rates as compared with other groups (P < 0.05). Also, supplementation of the IVC medium with 0.5 μM of resveratrol had beneficial effects on trophectoderm cells (TE), inner cell mass (ICM), and TCN of blastocysts. In the second experiment, the same concentrations of resveratrol (0, 0.1, 0.25, 0.5, 2.0, and 5.0 μM) were applied during IVM and IVC. Therefore, oocytes were matured in vitro in the presence of different concentrations of resveratrol for 22-24 h. After in vitro fertilization, presumptive zygotes were cultured in media containing 0, 0.1, 0.25, 0.5, 2.0, and 5.0 μM of resveratrol for 8 d. No significant difference was found in the percentage of oocytes developed to MII (0, 0.1, 0.25, 0.5, and 2.0 μM of resveratrol), but the percentage of oocytes developed to MII were significantly lower in 5.0 μM of resveratrol in comparison with other groups. Addition of 0.5 μM of resveratrol to the maturation and culture media significantly increased morula and blastocyst rates compared with other groups (P < 0.05). However, a too high concentration of resveratrol (5.0 μM) during IVM and IVC decreased cleavage, morula, and blastocyst rates compared with low concentrations (P < 0.05). Treatment with 0.5/0.5 μM of resveratrol during IVM/IVC significantly improved the TE, ICM, and TCN of blastocysts. In conclusion, sequential treatment with 0.5 μM of resveratrol during IVM and IVC and during IVC alone improved the developmental competence of oocytes, which was reflected in higher blastocyst rates and TCN of blastocysts.

Environment and Male Fertility: Effects of Benzo-α-Pyrene and Resveratrol on Human Sperm Function In Vitro

Lifestyle, cigarette smoking and environmental pollution have a negative impact on male fertility. Therefore, the aim of this study was to evaluate the in-vitro effects of benzo-α-pyrene (BaP) and aryl hydrocarbon receptor (AHR) agonists on motility and bio-functional sperm parameters. We further assessed whether resveratrol (RES), an AHR antagonist and antioxidant molecule, had any protective effect. To accomplish this, 30 normozoospermic, healthy, non-smoker men not exposed to BaP were enrolled. Spermatozoa of 15 men were incubated with increasing concentrations of BaP to evaluate its effect and to establish its dose response. Then, spermatozoa of the 15 other men were incubated with BaP (15 µM/mL), chosen according to the dose-response and/or RES to evaluate its antagonistic effects. The effects of both substances were evaluated after 3 h of incubation on total and progressive sperm motility and on the following bio-functional sperm parameters evaluated by flow cytometry: Degree of chromatin compactness, viability, phosphatidylserine externalization (PS), late apoptosis, mitochondrial membrane potential (MMP), DNA fragmentation, degree of lipoperoxidation (LP), and concentrations of mitochondrial superoxide anion. Benzo-α-pyrene decreased total and progressive sperm motility, impaired chromatin compactness, and increased sperm lipoperoxidation and mitochondrial superoxide anion levels. All these effects were statistically significant at the lowest concentration tested (15 µM/mL) and they were confirmed at the concentration of 45 µM/mL. In turn, RES was able to counteract the detrimental effects of BaP on sperm motility, abnormal chromatin compactness, lipid peroxidation, and mitochondrial superoxide. This study showed that BaP alters sperm motility and bio-functional sperm parameters and that RES exerts a protective effect on BaP-induced sperm damage.

Effects of oligomeric proanthocyanidins on quality of boar semen during liquid preservation at 17 °C

The use of antioxidants is an important aspect in the preservation of boar semen. Oligomeric proanthocyanidins (OPC) are an effective natural antioxidants that scavenges free radicals and reactive oxygen species (ROS). This study was designed to investigate the antioxidative effect of OPC on boar semen quality during liquid preservation at 17 °C. The effects of different concentrations of OPC on sperm quality variables, antioxidant effects and fertility were analyzed in this experiment. Semen collected from six Guanzhong-Black boars and was diluted with Beltsville thawing solution (BTS). During the process of liquid preservation at 17 °C, the variables assessed were measured and analyzed every 24 h. The addition of OPC improved boar sperm motility, acrosome integrity, membrane integrity, and mitochondrial membrane potential as compared with that of the control group (P <  0.05). Meanwhile, malondialdehyde content (MDA) and ROS content was less after adding OPC, thereby improving the total antioxidant capacity (T-AOC) (P <  0.05). Different concentrations of OPC have different degrees of protective effects on boar semen quality. The results indicate that 50 μg/mL of OPC was the optimum concentration, and that the conception rate, litter size, and survival rate increased at this concentration as compared with that of the control group (P <  0.05). In summary, the addition of OPC to BTS diluents can improve the quality of boar semen at 17 °C during liquid preservation. Further research is needed to understand the mechanism by which OPC provides protection to boar semen during preservation in vitro.

Effect of Astragalus polysaccharide addition to thawed boar sperm on in vitro fertilization and embryo development

It is important to utilize an antioxidant to ameliorate oxidative damage during boar sperm cryopreservation and thawing. Some studies have shown that Astragalus polysaccharide (APS) has antioxidant capabilities in sperm storage at low temperatures. However, the effects of APS on thawed sperm are unclear. In this study, the effect of supplementation of thawing boar semen extender with APS (0.5, 1, 5, 10 mg/mL) on sperm quality parameters (viability, motility, acrosome integrity and mitochondrial activity) was evaluated. Next, we investigated the effect of APS (0.5 mg/mL) supplementation on antioxidant parameters. Semen from two straws was thawed and diluted with three volumes of Beltsville Thawing Solution (BTS) and immediately divided into a control group without addition of antioxidants (CTR) and the APS group. Sperm and antioxidant parameters were evaluated in the CTR and APS groups after 1 h of incubation at 37 °C. Finally, we studied the effect of APS (0.5 mg/mL) supplementation on in vitro fertilization (IVF) and embryo development. The addition of different doses of APS to thawed sperm did not induce any significant effects on the sperm viability or motility compared to the sperm without APS treatment. However, the addition of 0.5 mg/mL APS to thawed sperm showed improved mitochondrial activity, higher penetration rate and increased total IVF efficiency compared with those of the control group. Moreover, our results indicate that the supplementation of APS in thawed sperm decreased the concentration of reactive oxygen species (ROS) and improved the activity of superoxide dismutase (SOD) and catalase (CAT). Finally, the addition of APS significantly increased the cleavage rate and blastocyst rate compared to those of the control group. In conclusion, the addition of APS to thawed boar sperm can enhance the antioxidant ability of sperm and improve in vitro fertilization (IVF) parameters and the outcomes of embryonic development. These results imply that APS has practical potential to enhance boar sperm reproductive performance.

Therapeutic Role of Green Tea Polyphenols in Improving Fertility: A Review

Sperm cells are highly sensitive to reactive oxygen species (ROS), which are produced during cellular oxidation. In normal cell biology, ROS levels increase with a decreasing antioxidant response, resulting in oxidative stress which threatens sperm biology. Oxidative stress has numerous effects, including increased apoptosis, reduced motion parameters, and reduced sperm integrity. In this regard, green tea polyphenols (GrTPs) have been reported to possess properties that may increase the quality of male and female gametes, mostly via the capability of catechins to reduce ROS production. GrTPs have antioxidant properties that improve major semen parameters, such as sperm concentration, motility, morphology, DNA damage, fertility rate, and gamete quality. These unique properties of green tea catechins could improve reproductive health and represent an important study area. This exploratory review discusses the therapeutic effects of GrTPs against infertility, their possible mechanisms of action, and recommended supportive therapy for improving fertility in humans and in animals.

Resveratrol significantly improves the fertilisation capacity of bovine sex-sorted semen by inhibiting apoptosis and lipid peroxidation

The aim of this study was to test the effects of five different concentrations (0, 10⁻³, 10⁻⁴, 10⁻⁵, and 10⁻⁶ M) of resveratrol (Res) supplementation in bull sperm washing and fertilisation medium on levels of reactive oxygen species (ROS), phosphatidylserine (PS) externalisation, mitochondrial membrane potential (Δψm), ATP and malondialdehyde (MDA), acrosomal integrity, blastocyst rate, and blastocyst quality after in vitro fertilisation (IVF). The results for sex-sorted sperm from three bulls showed: (1) ROS and MDA levels in 10⁻³ M and 10⁻⁴ M Res groups were significantly lower than those of controls (P < 0.05); (2) the percentage of viable sperm, percentage of sperm with high Δψm, and the ATP content in 10⁻³ M and 10⁻⁴ M Res groups were significantly higher than those of controls (P < 0.05); (3) the percentage of viable sperm with acrosomal integrity, and the blastocyst percentage and quality of the 10⁻⁴ M Res group were significantly higher than those of controls (P < 0.05). In conclusion, 10⁻⁴ M Res supplementation in washing and fertilisation medium of sex-sorted bull sperm significantly decreased ROS, PS externalisation, and MDA, and protected mitochondrial function and acrosomal integrity, thereby increasing blastocyst percentage and quality following IVF.

A mechanism by which Astragalus polysaccharide protects against ROS toxicity through inhibiting the protein dephosphorylation of boar sperm preserved at 4 °C

Numerous studies have shown that Astragalus polysaccharide (APS) has strong antioxidant effects and high practical value for preserving semen at low temperatures in vitro. However, to date, little attention has been paid to the precise mechanism of APS in sperm preservation at 4 °C. Thus, to gain further insight into the protective effects of APS, the present study was performed to assess the changes in sperm quality parameters, antioxidant capacity, ATP content, and protein phosphorylation levels. Here, we demonstrated that supplementation with APS could effectively preserve boar sperm quality parameters such as sperm motility, acrosome integrity, and mitochondrial membrane potential. Moreover, we found that the positive effects of APS on boar sperm quality were mainly due to the elimination of excessive mitochondrial ROS, the improvement of antioxidant capacities and the enhancement of ATP levels. Interestingly, by conducting a series of studies on protein phosphorylation, we also discovered that APS could protect boar sperm from oxidative stress and energy deficiency through inhibiting the protein dephosphorylation caused by ROS via the cAMP-PKA signaling pathway. To our knowledge, this is the first exploration of the molecular mechanism underlying the protective roles of APS toward ROS toxicity from the perspective of energy metabolism and protein modification. This study comprehensively provides novel insights into the action mechanism of the protective effects of antioxidants on sperm stored at 4 °C and reveals the practical feasibility of using APS as a boar semen extender supplement for assisted reproductive technology.