Semen supplementation with palmitoleic acid promotes kinematics, microscopic and antioxidative parameters of ram spermatozoa during liquid storage

Regulation of semen quality by fatty acids in diets, extender, and semen

Fatty acids (FAs) are classified into different types according to the degree of hydrocarbon chain saturation, including saturated fatty acids (SFAs), monounsaturated fatty acids (MUFAs), omega-3 polyunsaturated fatty acids (omega-3 PUFAs) and omega-6 polyunsaturated fatty acids (omega-6 PUFAs), which play an important role in maintaining semen quality. This review focuses on the regulation of FAs in semen, diet and extender on semen quality, and expounds its effects on sperm motility, plasma membrane integrity, DNA integrity, hormone content, and antioxidant capacity. It can be concluded that there are species differences in the FAs profile and requirements in sperm, and their ability to regulate semen quality is also affected by the addition methods or dosages. Future research directions should focus on analyzing the FAs profiles of different species or different periods of the same species and exploring suitable addition methods, doses and mechanism of regulating semen quality.

Assessment of the effect of kinetin against formic acid toxicity in chicken embryo model

The current study was designed to investigate the in ovo injection of formic acid (FA) on hatchability rate (HR; Experiment 1) and the potential ameliorative role of kinetin concurrent with FA on biochemical parameters of hatched broilers (Experiment 2). In Experiment 1, live embryonated eggs (n = 280; Day 4 of incubation) were in ovo injected with 0.03, 0.06, 0.125, 0.25, 0.50, 1, 2, 4, 8, 16 and 32 m m FA. In Experiment 2, intra-yolk-sac administration of toxic doses of FA (2 m m) concurrent with kinetin at 50, 100 or 200 µ m were evaluated on hatched embryos. The amount of malondialdehyde (MDA), total antioxidant capacity (TAC), total nitrate-nitrite (TNN), total lipid hydroperoxide (TLHP) and superoxide dismutase (SOD) activity was measured in serum, liver, heart and brain tissues. The results revealed that injection of 2 mM FA significantly increased mortality compared to the control group (p < 0.05). Concurrent administration of 50 or 100 µ m kinetin + 2 m m FA increased HR to 10% and 20% compared to the FA-alone-treated group, respectively. Intra-yolk-sac-received FA group showed greater amounts of MDA, TLHP and TNN and lesser amounts of TAC and SOD activity in serum and tissue samples of liver, heart and brain compared to control groups (p < 0.001). In comparison to the FA-alone-treated group, all doses of kinetin were able to increase the TAC levels in serum and tissue samples when administered concurrently with FA. The doses of 50 and 100 µ m kinetin were efficacious to ameliorate the toxic role of FA injection on SOD activities (p < 0.001). Co-injection of 100 µ m kinetin plus FA significantly reduced the amounts of MDA, TNN and TLHP in measured samples compared to the FA-alone-injected group (p < 0.001). Our results indicated that kinetin (especially at 100 µ m doses) would ameliorate the toxic effects of FA on developing live chicken embryos.

Coenzyme Q10 improves the quality of sheep sperm stored at room temperature by mitigating oxidative stress

The purpose of this experiment was to explore whether coenzyme Q₁₀ (CoQ₁₀ ) improves the quality of sheep semen stored at room temperature by attenuating oxidative stress. Semen was diluted without (control group), and with antioxidants (5, 50, 250, and 500 μmol/L CoQ₁₀ ). Sperm kinetic parameters and plasma membrane integrity were determined, and the reactive oxygen species (ROS), malondialdehyde (MDA), adenosine triphosphate (ATP), mitochondrial membrane potential (MMP), total antioxidant capacity (TAOC), catalase (CAT), and superoxide dismutase (SOD) activity were evaluated on the fifth day of semen preservation. The results showed that compared with the control group, the progressive motility in the 50 μmol/L group was higher (p < 0.05) within 2-5 days, and the plasma membrane integrity of sperm was higher in the 50 μmol/L group. The ROS content in the 5 and 50 μmol/L groups was reduced. The MDA level was reduced in the CoQ₁₀ supplementation groups (p < 0.05). Additionally, the CAT, SOD, TAOC, ATP and MMP levels in the 50 μmol/L group were higher than those in the control group (p < 0.05). In conclusion, CoQ₁₀ improved the quality of ram semen by alleviating oxidative stress, and 50 μmol/L CoQ₁₀ was the optimum concentration.

Chlorogenic Acid Improves Quality of Chilled Ram Sperm by Mitigating Oxidative Stress

Simple Summary

Sheep sperm is extremely sensitive to reactive oxygen species (ROS) and can produce a large amount of ROS during chilling storage, leading to a decline in semen quality. Adding antioxidants is an important method to improve semen quality. Chlorogenic acid (CGA) is a kind of plant extract with an antioxidant capacity, which can effectively eliminate free radicals and improve the antioxidant capacity of semen. However, its role in the chilling storage of Hu ram semen is not clear. Therefore, CGA with different concentrations was added to chilling storage extender to investigate its effect on chilled ram sperm. The results of this study revealed that CGA with proper concentration had a positive effect on chilled Hu ram sperm and 0.8 mg/mL CGA had the best effect.

Abstract

The purpose of this study was to investigate whether the addition of chlorogenic acid (CGA) to a sheep semen extender could improve the quality of chilled sheep sperm. Ejaculates (n = 80) were collected from five Hu rams with an artificial vagina. The ejaculates were mixed and divided into five equal parts, diluted with a CGA-free Tris–egg yolk extender (control), or supplemented with 0.2, 0.4, 0.8, and 1.2 mg/mL. The sperm kinematic parameters (viability, progressive motility), functional integrity of plasma membrane and acrosome, adenosine triphosphate (ATP) concentration and antioxidant parameters (Catalase (CAT), Superoxide dismutase (SOD) activity, total antioxidant capacity (T-AOC), ROS level and Malondialdehyde (MDA) content) were evaluated during storage of the semen. The results indicated that: PM, plasmatic membrane integrity and acrosomal integrity in 0.8 mg/mL CGA were higher (p < 0.05) from day 1 to 5. The ROS level in CGA groups was lower than the control (p < 0.05). CAT, SOD, ATP, and T-AOC were highest at 0.8 mg/mL concentration within 1 to 5 days. The above results indicated that the right concentration of CGA improved the quality of Hu ram sperm during chilling storage.

Molecular insights into the divergence and diversity of post-testicular maturation strategies

Competition to achieve paternity has coerced the development of a multitude of male reproductive strategies. In one of the most well-studied examples, the spermatozoa of all mammalian species must undergo a series of physiological changes as they transit the male (epididymal maturation) and female (capacitation) reproductive tracts prior to realizing their potential to fertilize an ovum. However, the origin and adaptive advantage afforded by these intricate processes of post-testicular sperm maturation remain to be fully elucidated. Here, we review literature pertaining to the nature and the physiological role of epididymal maturation and subsequent capacitation in comparative vertebrate taxa including representative species from the avian, reptilian, and mammalian lineages. Such insights are discussed in terms of the framework they provide for helping to understand the evolutionary significance of post-testicular sperm maturation.

In vitro supplementation with unsaturated fatty acids improves boar sperm viability after storage at 6 °C

Liquid preservation of the cold-sensitive boar sperm at a lesser temperature than the standard 17 °C would reduce bacterial growth and minimize the use of antibiotics. There was assessment, therefore, of the capacity of individual fatty acids bound to fatty acid free BSA to improve sperm survival at 6 °C because oxidative stress and lipid degradation are prominent detrimental factors. Different effects of the fatty acids were observed. Supplementation with naturally occurring fatty acids (linolenic, linoleic, oleic, palmitoleic acid), which may become metabolically incorporated into sperm lipids, increased the number of motile and progressively motile sperm after 2 days of storage during a thermo-resistance test (5 h at 38 °C) to that of control samples preserved at 17 °C in pure Beltsville Thawing Solution. With the exception of linolenic acid, all naturally occurring fatty acids enhanced the number of sperm with active mitochondria after 3 days of storage. Palmitoleic acid was the most effective supplement with effects already present when sperm were re-warmed for 30 min after 2 and 7 days of storage. The non-endogenous, non-integrated timnodonic acid (20:5) had no effect on sperm variables. Because the application of individual fatty acids attached to BSA had differing effects in preserving boar sperm at 6 °C, the use of combinations of fatty acids could be more efficacious than with use of natural lipid supplements for low temperature preservation of sperm.

Modification of Crocodile Spermatozoa Refutes the Tenet That Post-testicular Sperm Maturation Is Restricted To Mammals

Competition to achieve paternity has contributed to the development of a multitude of elaborate male reproductive strategies. In one of the most well-studied examples, the spermatozoa of all mammalian species must undergo a series of physiological changes, termed capacitation, in the female reproductive tract before realizing their potential to fertilize an ovum. However, the evolutionary origin and adaptive advantage afforded by capacitation remains obscure. Here, we report the use of comparative and quantitative proteomics to explore the biological significance of capacitation in an ancient reptilian species, the Australian saltwater crocodile (Crocodylus porosus,). Our data reveal that exposure of crocodile spermatozoa to capacitation stimuli elicits a cascade of physiological responses that are analogous to those implicated in the functional activation of their mammalian counterparts. Indeed, among a total of 1119 proteins identified in this study, we detected 126 that were differentially phosphorylated (± 1.2 fold-change) in capacitated versus, noncapacitated crocodile spermatozoa. Notably, this subset of phosphorylated proteins shared substantial evolutionary overlap with those documented in mammalian spermatozoa, and included key elements of signal transduction, metabolic and cellular remodeling pathways. Unlike mammalian sperm, however, we noted a distinct bias for differential phosphorylation of serine (as opposed to tyrosine) residues, with this amino acid featuring as the target for ∼80% of all changes detected in capacitated spermatozoa. Overall, these results indicate that the phenomenon of sperm capacitation is unlikely to be restricted to mammals and provide a framework for understanding the molecular changes in sperm physiology necessary for fertilization.

Influence of idebenone on ram semen quality stored at 4°C

The current study was designed to investigate the effect of idebenone (Id), an antioxidant on ram semen quality. Semen samples were collected, pooled and diluted in a Tris-based extender supplemented with 0, 1, 2, 4 and 8 µM idebenone. Computer-assisted sperm analysis was used to evaluate spermatozoa kinematics. Sperm viability and membrane functionality were assessed respectively, by eosin-nigrosin staining and HOS test. Biochemical assays were carried out to measure different metabolites in spermatozoa and medium at 0, 24, 48 and 72 hr. Total and forward progressive motility were greater in 1, 2 and 4 µM idebenone treated groups compared to control at 24, 48 and 72 hr time points (p < 0.05). Semen supplementation with Id significantly increased viability and functionality of spermatozoa membrane during storage (p < 0.05). Lower amounts of lipid hydroperoxides in medium and spermatozoa were observed in Id-treated groups compared to control one at 24 and 48 hr of storage (p < 0.05). Medium and spermatozoa amounts of malondialdehyde and nitric oxide were less in Id 4 µM group compared to the control at 72 hr (p < 0.05). Total antioxidant capacity values and superoxide dismutase activity of spermatozoa and medium were greater in 2 and 4 µM idebenone treated groups in comparison with the control at 72 hr (p < 0.05). Results of the current study indicated that ram semen supplementation with Id at 4 µM level improved quality by ameliorating nitrosative and peroxidative stress, hence could be considered as an antioxidant additive during storage at 4°C.