Beneficial and harmful effects of cyclodextrin-vitamin E complex on cryopreserved ram sperm

Recent approaches in the use of antioxidants and proteomic modifications in ram semen preservation

Sperm preservation is a well-established technique in reproductive biotechnology that is widely used to maintain the genetic quality of male individuals. However, there are several factors during the preservation process that can affect the vitality, functionality, and quality of sperm, thereby reducing their fertility potential after thawing. One of these factors is the synthesis of high levels of oxidative stress (OS) during semen preservation, which can have detrimental effects on sperm health and functionality. To counter the negative impact of OS on sperm, researchers have explored the supplementation of several exogenous antioxidants in the extenders used to preserve ram sperm. This approach has shown promising results in improving sperm health, functionality, and fertility potential in ram. Additionally, the preservation process can induce modifications in the ram sperm proteome. By employing targeted proteomics techniques, researchers have been able to identify and modify specific proteins in cryopreserved ram sperm, potentially offering further improvements in the quality of the cryopreserved ram sperm. In summary, this review provides a comprehensive overview of the antioxidants and targeted proteomics modifications that have been investigated for enhancing ram sperm preservation. These advancements aim to mitigate the negative effects of OS and optimize the techniques used in preserving ram sperm.

Metformin improves sheep sperm cryopreservation via vitalizing the AMPK pathway

Adenosine 5'-monophosphate (AMP)-activated protein kinase (AMPK) is a key regulator of sperm function and physiological metabolism. Metformin, an inexpensive and effective antioxidant, is known to play an important role in the activation of AMPK. Therefore metformin has potential to improve sperm cryopreservation. The aim of this study was to investigate the effect of metformin during semen cryopreservation of sheep and to find the most effective concentration in freezing extender. Semen were cryopreserved with extender containing different concentrations of metformin (0, 0.25, 0.5, 1.0, 2.0 and 4.0 mmol/L). Sperm motility, acrosome integrity and plasma membrane integrity were measured after semen freezing and thawing. All results showed that sperm quality was significantly increased in the 1.0 mmol/L metformin-treated group compared with the control group (P < 0.05). In addition, the study showed that metformin effectively reduced the content of malondialdehyde (MDA) and reactive oxygen species (ROS), and increased the activity of glutathione peroxidase (GSH-Px), superoxide dismutase (SOD), catalase (CAT) and total antioxidant capacity (T-AOC) of freeze-thawed sperm (P < 0.05). The optimal concentration of metformin was 1.0 mmol/L. Moreover, the results showed that AMPK was localized in the acrosome region, junction and midsection of sperm, and p-AMPK was distributed in the post-acrosomal region, junction and midsection. Western blot analysis indicated that 1.0 mmol/L metformin stimulated the phosphorylation of AMPK in sperm. Further results showed that 1.0 mmol/L metformin significantly increased the mitochondrial membrane potential (ΔΨm), ATP content, glucose uptake and lactate efflux of post-thawed sperm through the AMPK pathway, improved sperm quality, and increased the cleavage rate of in vitro fertilization (P < 0.05).

Influence of trans-ferulic acid on the quality of ram semen upon cold preservation

BACKGROUND

Due to lower antioxidant capacity and higher amounts of polyunsaturated fatty acids, ram spermatozoa are very susceptible during cooling process.

OBJECTIVES

The objective was to examine the effect of the trans-ferulic acid (t-FA) on the ram semen during liquid preservation.

METHODS

Semen samples were collected from the Qezel rams, pooled, and extended with the Tris-based diluent. Pooled samples enriched with different amounts of the t-FA (0, 2.5, 5, 10, and 25 mM) and preserved at 4°C for 72 h. Spermatozoa's kinematics, membrane functionality, and viability were assessed by CASA system, hypoosmotic swelling test, and eosin-nigrosin staining, respectively. Moreover, biochemical parameters were measured at 0, 24, 48, and 72 h.

RESULTS

Results showed that 5 and 10 mM t-FA improved forward progressive motility (FPM) and curvilinear velocity compared to the other groups at 72 h (p < 0.05). Samples treated with 25 mM t-FA showed the lowest total motility, FPM, and viability at 24, 48, and 72 h of storage (p < 0.05). Higher total antioxidant activity levels were observed in the 10 mM t-FA-treated group compared to the negative control at 72 h (p < 0.05). Treatment with 25 mM t-FA increased malondialdehyde amounts and decreased superoxide dismutase activity compared to other groups at the final time assessment (p < 0.05). Nitrate-nitrite and lipid hydroperoxides values were not affected by treatment.

CONCLUSIONS

The current study indicates the positive and negative influences of different concentrations of t-FA on the ram semen upon cold storage.

The Effect of Oral Vitamin E on Semen Parameters and IVF Outcome: A Double-Blinded Randomized Placebo-Controlled Clinical Trial

Background

Male infertility is a main clinical problem that affects about 7% of all men worldwide. Many patients with male infertility are caused by a reduced antioxidant capacity of semen. Several antioxidant supplements, especially vitamin E, are proposed to help male infertility treatment. This project was goaled to study the effects of oral synthetic vitamin E (400 IU/day) for eight weeks on betterment of semen parameters and pregnancy rate.

Methods

After dropping the cases, 124 infertile couples with a male factor who were admitted to the IVF program were included. The male patients with idiopathic abnormal motility and/or morphology were randomized into two groups: 61 receiving vitamin E and 63 as the control group receiving placebo for eight weeks. The pretreatment semen parameters of both groups were compared with those of posttreatment. The pregnancy outcomes were considered between the two groups.

Results

There were no significant differences statistically between before and after treatment in the term of sperm volume, count, motility, and morphology. Furthermore, the IVF outcomes of the two groups were not different significantly, either. Interestingly, the percent of normal sperm in the placebo group was significantly decreased after eight weeks.

Conclusion

Vitamin E supplementation might neutralize free radical activity to keep sperm from more oxidative damages. Further studies regarding the influence of higher acceptable doses of vitamin E on semen characteristics and fertility rates are needed. This study was registered as a two-arm, blinded, randomized, placebo-controlled clinical trial (IRCTID: IRCT2014020616506N1, 2014-03-18).

Ameliorative role of trans-ferulic acid on induced oxidative toxicity of rooster semen by β-cyfluthrin during low temperature liquid storage

Current study was designed to evaluate the effects of β-cyfluthrin, as a toxicant substance, and trans-ferulic acid (trans-FA), as a protective agent, on different parameters of rooster semen upon liquid storage. For this purpose, semen samples of roosters (Ross 308, n = 10, 32-wk-old) were collected twice a week. Good quality samples (≥70% progressive motion) were diluted, pooled and then divided for the purposes of the study. In the first experiment, motility of spermatozoa was evaluated following exposure to different concentrations of β-cyfluthrin (1, 2.5, 5, 10, 20, 40, and 80 µM) at 0, 24, and 48 h of storage. In the second experiment, constant doses of β-cyfluthrin (10 µM) alone or in combination with trans-FA (10, 25 mM) were assessed on motility and viability of spermatozoa at 0, 24, and 48 h time points. Moreover, amounts of malondialdehyde (MDA), total antioxidant capacity (TAC), total nitrate-nitrite, total hydroperoxide (HPO), and activity of superoxide dismutase (SOD) were evaluated in the homogenate of spermatozoa-diluent at studied time points. Results of the first experiment showed that amounts of β-cyfluthrin greater than 5 µM, significantly reduced the motility of spermatozoa at 24 and 48 h of storage (P < 0.05). The second experiment demonstrated that, trans-FA especially at 10, 25 mM doses restored the motility and viability of spermatozoa compared to β-cyfluthrin treated group (P < 0.05). Amounts of MDA (10, 25 mM), hydroperoxide (10, 25, and 50 mM), and nitrate-nitrite (10, 25, and 50 mM) were lower and TAC (10 and 25 mM) were greater in trans-FA + β-cyfluthrin treated groups compared to β-cyfluthrin alone treated samples (P < 0.05). However, activity of SOD did not show significant changes by the treatment (P > 0.05). It seems that trans-FA could ameliorate toxic effect of β-cyfluthrin via reduction of peroxidative (as evident by measurement of MDA) and nitrosative (as evident by measurement of nitrate-nitrite) reactions over cold preservation of rooster semen.

Effect of resveratrol supplementation to Triladyl® on the quality of ram chilled semen

The present investigation aimed to estimate the in vitro effects of resveratrol (RES) on the quality of chilled ram semen. Resveratrol was added to Triladyl® in three different concentration as 0 (control), 200 or 400 μM. Semen was collected from three Najdi rams, pooled and extended with one of three previous extenders for a final concentration of 600×106 sperm/ml. Then, the diluted semen was cooled gradually, and stored at 4°C. The total motility, viability, plasma membrane integrity and acrosome integrity were assessed at 0, 24, 72 and 120 h of storage. The thermal incubation test was evaluated at day 7. The survival time, total motility and the progressive motility were registered at day 15 of storage. After 4 h of incubation, the percentage of live sperm was significantly lower in the control group than in other groups. Results of survival time, total motility and progressive motility at day 15 of liquid storage were significantly higher in RES groups than that of the control. Based on the results of incubation resistance, survival time, total and progressive motility, it could be concluded that adding 200 and 400 μM of RES to Triladyl extender can improve the quality of ram semen during chilled storage at 4°C.

Effect of Alpha-Linolenic Acid with Bovine Serum Albumin or Methyl-Beta-Cyclodextrin on Membrane Integrity and Oxidative Stress of Frozen-Thawed Boar Sperm

The study was conducted to investigate the effects of alpha-linolenic acid (ALA) combined with bovine serum albumin (BSA) or methyl-beta-cyclodextrin (MBCD) on plasma and acrosomal membrane damages, mitochondrial activity, morphological abnormality, motility, and oxidative stress in frozen-thawed boar sperm. In previous our study, 3 ng/mL ALA had been shown protective effect during freezing process of boar sperm. Therefore, we used 3 ng/mL ALA in present study and ALA was combined with same molar ratio of BSA or MBCD (ALA+BSA and ALA+MBCD, respectively). To confirm the effect of two carrier proteins, same volume of BSA and MBCD without ALA were added during cryopreservation. Membrane damage, mitochondrial activity, reactive oxygen species (ROS) and lipid peroxidation (LPO) levels were measured using flow cytometry, and movement of sperm tail as motility parameter and morphological abnormality were observed under light microscope. In results, all of sperm parameters were enhanced by ALA combined with BSA or MBCD compared to control groups (p<0.05). Mitochondrial activity, morphological abnormality, ROS and LPO levels in ALA+BSA or MBCD groups were no significant difference compared with ALA, BSA and MBCD treatment groups. On the other hand, plasma and acrosomal membrane intact, and sperm motility in ALA+MBCD group were higher than single treatment groups (p<0.05), whereas ALA+BSA did not differ. Our findings indicate that carrier proteins such as BSA and MBCD could improve the effect of ALA during cryopreservation of boar sperm, and treatment of ALA with carrier proteins enhance membrane integrity, mitochondrial activity through reduction of ROS-induced LPO.