Survival of buffalo bull spermatozoa: effect on structure and function due to alpha-lipoic acid and cholesterol-loaded cyclodextrin

Collection, Handling, and Preservation of Wild Bird Semen: Current Status, Challenges, and Perspectives

Semen preservation is a significant biotechnology used to safeguard the genetic material of birds, especially those with declining populations, through biobanking. However, there are limited reports on the successful chilling or cryopreservation of wild bird semen. In general, these techniques are not yet well-established for several species of wild birds and pose several challenges such as the need for bird handling and training, contamination of semen samples, low volume of semen collected, and inefficient preservation protocols. To address these challenges and improve post-thawing outcomes, new possibilities are being investigated, including alternative collection methods to traditional digital massage, the use of antioxidants and enzymes in the medium for chilling or freezing, storage methods using different straws from the usual pellet, and slower freezing rates. This review aims to discuss the various aspects of applying semen preservation in wild birds to create germplasm banks, highlighting the primary results obtained and the challenges that need to be addressed.

Effects of alpha lipoic acid supplementation on post-thaw quality of drone semen

This study aimed to determine the effect of alpha-lipoic acid (ALA) on post-thaw quality of bee semen. In the study, semen from sexually mature drone were collected. A series of experiments were carried out in which the retrieved semen was diluted with diluents containing different ALA concentrations or without ALA supplement (control). Cryopreserved sperm were thawed, and evaluated for motility (phase-contrast microscope), plasma and acrosomal membrane integrity, mitochondrial membrane potential, and DNA fregmantation. The results obtained showed that the highest motility after thawing was observed in the groups containing ALA 0.25 mmol (P < 0.05). Likewise, plasma membrane integrity was found to be better preserved in the ALA 0.25 mmol-added group than in other groups. Acrosomal integrity were also higher in the ALA-containing groups than in the control group (P < 0.05). The results of this study show that ALA supplementation especially at 0.25 mmol improved post-thawed sperm motility, plasma membrane functionality, and mitochondrial membrane potantial quality of honeybee semen.

Alpha-lipoic acid improves the quality of ram spermatozoa stored at 4°C by reducing oxidative stress and increasing mitochondrial potential

Introduction

Ram spermatozoa inevitably produce a large number of reactive oxygen species (ROS) during liquid storage, leading to oxidative stress and a decline of spermatozoa quality. Therefore, it is particularly important to add exogenous antioxidants during the process of semen liquid preservation. The purpose of this study is to investigate whether adding alpha-lipoic acid (ALA) to ram semen can reduce oxidative stress and enhance spermatozoa quality during the liquid storage at 4°C.

Methods

Different concentrations of ALA (0, 0.025, 0.05, 0.1, 0.5, 1 mM) were added to semen and stored at 4°C. During storage at 4°C, spermatozoa motility, kinetic parameters, membrane integrity, acrosome integrity, energy metabolism parameters (mitochondrial membrane potential (ΔΨM) and adenosine triphosphate (ATP)) and oxidative stress parameters [ROS, malondialdehyde (MDA), total antioxidant capacity (TAC), superoxide dismutase (SOD)] were assessed.

Results and discussion

The results indicated that 0.1 mM ALA significantly (p<0.05) improved spermatozoa total motility (TM) and progressive motility (PM), plasma membrane integrity, acrosome integrity, ΔΨM, ATP, TAC, and SOD, while significantly (p<0.05) reducing spermatozoa ROS and MDA content compared to the control group. In conclusion, ALA can reduce damage caused by oxidative stress in spermatozoa and effectively improve the quality of semen preserved at 4°C. And the optimal concentration is 0.1 mM.

Alpha-lipoic acid improves bovine preimplantation blastocyst quality and cryotolerance

In vitro embryo production has grown in recent decades due to its great potential for cattle production. However, the quality of in vitro-produced embryos is lower compared with those produced in vivo. The postfertilization culture environment has a major influence on bovine embryo quality. We hypothesize that the inclusion of the inclusion of alpha-lipoic acid (ALA) in the in vitro culture (IVC) medium during the first 24 h would have positive effects on embryo development in vitro and cryotolerance. The aims of this study were to evaluate the antioxidant effect of ALA in IVC medium for 24 h on bovine zygotes (21 h post in vitro fertilization, IVF), day 2 cleaved embryos (46 h post-IVF), and to assess embryo quality, developmental competence, and cryotolerance after vitrification. In all experiments, IVC medium was the Control, and 2.5 μM ALA was the treatment implemented. Viability and reactive oxygen species (ROS) levels in zygotes and day 2 embryos did not differ from the Control (P > 0.05). Supplementation with ALA increased total blastocyst and hatching rates (P < 0.05). It also improved embryo quality, evidenced by the increased blastocyst total cell number and the percentage of excellent-quality embryos observed (P < 0.05). In embryos cultured with ALA and then vitrified, ALA reduced intracellular ROS levels in warmed blastocysts (P < 0.05). In conclusion, ALA supplementation to IVC medium during 24 h is a new advantage in improving embryo quality for assisted bovine reproduction.

Supplementation of Alpha-lipoic acid-loaded nanoliposomes in semen extender improves freezability of buffalo spermatozoa

This research was designed to explore the protective effect of alpha-lipoic acid-loaded nanoliposomes (ALAN) during cryopreservation of buffalo sperm. Buffalo semen was cryopreserved in a tris-citrate egg yolk extender without any supplement (ALAN0, control group) or with ALAN at levels of 25, 50, 75 or 150 µg (ALAN25, ALAN50, ALAN75 and ALAN150, respectively). The ALAN had a size of 171.80 nm and a negative zeta potential (- 43.40 mV). The progressive motility, vitality and membrane integrity significantly improved in all ALAN groups (except ALAN25 for membrane integrity). ALAN150 group exhibited the best values of progressive sperm motility, vitality and membrane integrity after thawing at 37 °C for 30 s or incubated for 2 h at 37 °C and 5% CO₂ compared with those in other groups. Both ALAN75 and ALAN150 groups significantly improved the TAC, GR and catalase, while lipid peroxidation and early apoptotic spermatozoa significantly decreased in ALAN150 group followed by ALAN75 group. Collectively, the adding ALAN to buffalo semen freezing extender plays a substantial shielding function against cryodamage by preserving the sperm functional parameters.

Effect of Milk Type Subjected to Different Heat Treatments on Cryo-Survivability and In Vivo Fertility of Buffalo (Bubalus bubalis) Spermatozoa in a Milk-Based Extender

Oxidative stress is a major contributory factor to cellular damage during semen cryopreservation and results in a decreased fertilizing capacity of cryopreserved bull sperm. The inclusion of exogenous antioxidants sometimes exerts deleterious effects on sperm quality. Thus, enhancing the endogenous production of antioxidants is a requirement. This study aimed to investigate the effect of milk type heated at different temperatures on the antioxidant potential of extenders, and the subsequent post-thaw quality parameters and in vivo fertility of buffalo bull semen. Cow (C) and buffalo whole milk (B) were used separately for semen extender preparation, heated at five different temperatures (T₁ = 90°C, T₂ = 100°C, T₃ = 110°C, T₄ = 120°C, T₅ = 130°C) for 10 minutes. Reactive sulfhydryl groups were measured in each subgroup by Ellman's reagents as CT₁ = 143.2 μM, CT₂ = 147.4 μM, CT₃ = 151.5 μM, CT₄ = 157.2 μM, CT₅ = 161.8 μM, BT₁ = 168.3 μM, BT₂ = 172.5 μM, BT₃ = 176.7 μM, BT₄ = 196.3 μM, and BT₅ = 205.7 μM. All semen samples were cryopreserved in milk-based extenders by using standard procedures. Post-thaw quality parameters including total and progressive motility, mitochondrial membrane potential, plasma membrane integrity, and acrosome integrity were found to be higher (p < 0.05) in the group (BT₃) containing buffalo milk heated at 110°C, whereas in the same group, lipid peroxidation was found to be lower (p < 0.05) as compared with other treatment groups and control group. In vivo fertility of cryopreserved buffalo sperm was compared among BT₃, CT₁ (conventionally used milk extender), and a Tris egg yolk extender group. The fertility rates [47% (54/114), 30% (33/108), and 36% (37/103)] were higher (p < 0.05) in BT₃ as compared with other groups. This study suggests that buffalo milk heated at 110°C has high antioxidant potential and improves post-thaw quality and in vivo fertility of cryopreserved buffalo bull semen.

Effects of alpha-lipoic acid on ram semen cryopreservation and post-thaw life span

The aim of the present study was to evaluate the effects of an alpha-lipoic acid-supplemented extender on ram semen at a post-thaw stage and after incubation (6 hr). Semen samples were collected from five Kivircik Rams. Pooled semen was diluted with an egg yolk-based extender with different concentrations of alpha-lipoic acid (0.25 mmol L^-1 , 0.5 mmol L^-1 and 1 mmol L^-1 ) and without alpha-lipoic acid. Motility, plasma membrane functional integrity (HOST), acrosome integrity (FITC-Pisum sativum agglutinin) and DNA integrity (TUNEL) were assessed at post-thaw and 6 hr after incubation of the frozen-thawed semen. At the post-thaw stage, 0.25 mmol L^-1 alpha-lipoic acid had a positive effect on sperm motility and plasma membrane functional integrity compared to the control group (p < .05). At the post-incubation stage (6 hr), it was determined that the motility and plasma membrane functional integrity of the antioxidant groups were adversely affected compared to the control group (p < .05) and 1 mmol L^-1 dose of alpha-lipoic acid had a harmful effect on DNA integrity compared to the control group (p < .05). The results of the study demonstrated that alpha-lipoic acid has positive effects at post-thaw but have harmful effects on long term to ram semen.

Antioxidants increase blastocyst cryosurvival and viability post-vitrification

STUDY QUESTION

What is the effect of antioxidants acetyl-L-carnitine, N-acetyl-L-cysteine and α-lipoic acid (A3) in vitrification and warming solutions on mouse blastocyst development and viability?

SUMMARY ANSWER

The combination of three antioxidants in vitrification solutions resulted in mouse blastocysts with higher developmental potential in vitro and increased viability as assessed by both an outgrowth model in vitro and fetal development following uterine transfer.

WHAT IS KNOWN ALREADY

The antioxidant combination of acetyl-L-carnitine, N-acetyl-L-cysteine and α-lipoic acid present in IVF handling and embryo culture media has significant beneficial effects on mouse embryo and fetal development, especially under oxidative stress.

STUDY DESIGN, SIZE, DURATION

The study was a laboratory-based analysis of an animal model. Rapid cooling through vitrification was conducted on F1 mouse blastocysts, with antioxidants (A3) supplemented in vitrification and/or warming solutions, followed by culture and embryo transfer.

PARTICIPANTS/MATERIALS, SETTINGS, METHODS

Pronucleate oocytes were collected and cultured in groups to Day 4 blastocysts. Expanded blastocysts were vitrified and warmed in solutions with and without the A3 antioxidants and cultured for a further 24 h. Blastocyst cell number and allocation, apoptosis and histone acetylation levels were all quantified, and viability through outgrowths and transfers assessed.

MAIN RESULTS AND THE ROLE OF CHANCE

Mouse blastocysts vitrified with no antioxidants had significantly lower cell numbers (P  < 0.001) and higher apoptotic cells (P  < 0.05) compared to non-vitrified embryos. Addition of combined A3 antioxidants to the vitrification and warming solutions resulted in a significant increase in inner cell mass cell (ICM) number (P  < 0.001) and total cell number (P  < 0.01), and an increase in outgrowth area (P < 0.05), which correlated with the increased fetal weight (P < 0.05), crown rump length (P < 0.05) and limb development (P < 0.05) determined following transfer compared to embryos with no antioxidants. Furthermore, while blastocyst vitrification significantly reduced acetylation levels (P < 0.05) compared to non-vitrified embryos, the inclusion of A3 antioxidants helped to ameliorate this.

LIMITATIONS, REASONS FOR CAUTION

Embryo development was only examined in the mouse.

WIDER IMPLICATIONS OF THE FINDINGS

Results in this study demonstrate that vitrification and warming of blastocysts have significant detrimental effects on embryo histone acetylation and subsequent viability. The presence of antioxidants in the vitrification solutions helps to alleviate the negative effects of cryopreservation. Our data indicate that antioxidants need to be present in the medium at the time of exposure to increased oxidative stress associated with vitrification and that prior exposure (i.e. during culture or IVF alone) is insufficient to protect cells against cryo-induced injury. Hence, A3 antioxidants may assist in maintaining the viability of vitrified human embryos in ART through the reduction of oxidative stress.

STUDY FUNDING/COMPETING INTEREST(S)

This work was funded by a research grant from Vitrolife AB (Sweden). The authors have no conflict of interest to declare.

Does alpha-lipoic acid-loaded nanostructured lipid carriers improve post-thawed sperm quality and ameliorate apoptosis-related genes of rooster sperm?

Oxidative stress could be prevented by antioxidant-loaded nanoparticles. The purpose of this study was to assess the effects of 10 (A10), 20 (A20), 30 (A30), 40 (A40), and 50 (A50) μM alpha-lipoic acid and alpha-lipoic acid nanostructured lipid carriers (ALN) at 10 (ALN10), 20 (ALN20), 30 (ALN30), 40 (ALN40), and 50 (ALN50) μM on post-thawed sperm quality, fertility, and apoptosis-related genes of rooster sperm. The extender supplemented with ALN30 led to higher total and progressive motility, straight-line velocity, and linearity in comparison to the control group. The ALN30 resulted in higher percentage of mitochondria activity and glutathione peroxidase level compared with control (P < 0.05). The extender supplemented with ALN30 led to lower percentage of apoptotic sperm, when compared with the control. CASPASE 3 expression in ALN30 was lower (P < 0.05) than the other groups. The results showed that BCL-2 mRNA expression of sperm was significantly (P < 0.05) higher in ALN30 compared with the other groups (P < 0.05). Higher percentages of fertility and hatchability rates were observed in ALN30 group. The results indicate that ALN30 could be regarded as a novel potential cryoprotectant for the cryopreservation of rooster semen. Therefore, nanostructured lipid carriers improve not only the active compound (such as alpha-lipoic acid) of biomedical applicability but also the potential for industrial application in sperm cryopreservation.

Effect of alpha-lipoic acid on oxidative stress, viability and motility in the common carp (Cyprinus carpio) spermatozoa after short-term storage and cryopreservation

As known for different metabolic functions, α-lipoic acid (ALA) has been tested for spermatozoa preservation of animals as well as of human, but not for fish spermatozoa. The present study determined the effects of ALA on short and long-term (cryopreservation) preservation of common carp (Cyprinus carpio) spermatozoa, for the first time. For that, spermatozoa were diluted in extenders containing 0 (control), 0.025, 0.05, 0.1, 0.5, 1, 2, 5, and 10 mM of ALA concentrations in both short-term preservation and cryopreservation. Spermatozoa motility parameters by computer-assisted semen analysis, viability, lipid peroxidation and catalase activity in spermatozoa were conducted in both 2nd and 120th hours of short-term storage and post-thaw samples. Higher percentages of total spermatozoa motility (80 ± 3) and viability (87 ± 3) were observed in 0.5 mM ALA group after 120 h of incubation. In post-thaw samples, higher percentages of these parameters were in 1 mM ALA group (74 ± 3 and 83 ± 2, respectively). Moreover, the results have shown that the addition of ALA until concentrations of 2 mM improved especially spermatozoa curvilinear velocity, maintained viability, and suppressed excessive lipid peroxidation during the preservations. In conclusion, the additions of 0.5 mM ALA for short-term preservation and 1 mM ALA for cryopreservation were the optimal concentrations, and shown the protective effects on common carp spermatozoa, when considering all measured parameters together.

Effect of carboxylated poly l-Lysine as a cryoprotectant on post-thaw quality and in vivo fertility of Nili Ravi buffalo (Bubalus bubalis) bull semen

Buffalo bull sperm are more prone to cryo-injuries. Glycerol being the most common permeable cryoprotectant exerts cytotoxic effects on sperm which cause a reduction in fertility. Thus, the exploration of new cryoprotectant is needed. For this purpose, we investigated the effect of carboxylated poly l-Lysine (CPLL) as cryoprotectant used with different concentrations of glycerol on post-thaw sperm motility, kinematics, plasma membrane integrity, mitochondrial membrane potential (MMP), lipid peroxidation (LPO), catalase concentration and in vivo fertility of Nili Ravi buffalo bull semen. In experiment 1, semen samples (n = 15, bulls = 3) were diluted with Tris-citrate-egg yolk extender containing different concentration of CPLL [0% (C0), 0.25% (C0.25), 0.5% (C0.5), 0.75% (C0.75), 1% (C1)]. Each concentration of CPLL was added in extender containing either 7% (G7) or 5% (G5) glycerol. Diluted semen samples were cooled and cryopreserved using standard procedures. Post-thaw total and progressive motility, plasma membrane integrity, acrosome integrity, and MMP were found higher (P < 0.05) in group (G5C0.75) containing 0.75% CPLL and 5% glycerol as compared to the control group (G7C0) and other groups while LPO was recorded lower (P < 0.05) in the same group (G5C0.75). In experiment 2, in vivo fertility was compared between G5C0.75 (5% Glycerol+ 0.75% CPLL; depicted better post-thaw quality) and control group G7C0. Buffaloes were inseminated after 24 h of onset of estrus. Pregnancy diagnosis was performed per rectum at least 60 days post insemination. The fertility rates [56% (58/102) vs. 36% (37/103)] were higher (P < 0.05) in G5C0.75 as compared to the control group G7C0. Based upon these results, this study concludes that the addition of 0.75% CPLL in combination with 5% glycerol in freezing extender improves the post-thaw structure, function and in vivo fertility of Nili Ravi buffalo bull semen.