Cryoprotective effect ofl-carnitine on motility, vitality and DNA oxidation of human spermatozoa

L-carnitine supplementation in conventional slow and ultra-rapid freezing media improves motility, membrane integrity, and fertilizing ability of dog epididymal sperm

This study aimed to assess the impact of L-carnitine (LC) supplementation in conventional-slow (CS) and ultra-rapid (UR) freezing media on post-thaw quality and fertilizing ability of dog epididymal spermatozoa. Sperm samples were collected from 60 epididymides obtained from 30 adult orchiectomized dogs via retrograde flushing. Twenty pooled sperm samples were then created (3 epididymal samples/pool). Four treatments were established according to the freezing method (CS and UR) and LC supplementation (5 and 0 mM [control, Co]): CS-LC5, CS-Co, UR-LC5, and UR-Co. The CS freezing involved exposing 0.25 mL straw to liquid nitrogen vapors (LN2), while UR freezing submerged 30-µL drops of sperm samples directly into LN2. Sperm kinematics, membrane integrity, and fertilizing ability (by heterologous in vitro fertilization using bovine oocytes) were evaluated for all treatments. Post-thaw results revealed that the CS freezing treatments resulted in significantly higher values (P < 0.05) of curvilinear and average-path velocities, and beat-cross frequency compared to the UR freezing treatments, regardless of LC supplementation. The CS-LC5 and UR-LC5 treatments cryoprotected the sperm by increasing (P < 0.05) the percentage of 'live-sperm/intact-acrosome' compared to their controls treatments CS-Co and UR-Co. Regarding fertilizing ability, the CS-LC5 treatment yielded a higher percentage (P < 0.05) of pronuclei formation compared to both UR treatments. The UR-LC5 treatment, however, obtained greater percentage (P < 0.05) than their control UR-Co. In conclusion, supplementation with L-carnitine in conventional-slow and ultra-rapid freezing improved sperm motility, plasma, and acrosome membranes integrity and fertilizing ability of dog epididymal spermatozoa.

l-carnitine enhances the kinematics and protects the sperm membranes of chilled and frozen-thawed Peruvian Paso horse spermatozoa

l-carnitine (LC) transports fatty acids to the mitochondria for energy production, reducing lipid availability for peroxidation through β-oxidation. This research examines the effect of LC supplementation to two skimmed milk-based extenders on the cryosurvival of chilled (5°C) and frozen-thawed Peruvian Paso horse spermatozoa .An initial experiment determined the optimal LC concentration (0, 1, 5, 10, 25, and 50 mM) when added to INRA-96® and UHT (skimmed milk + 6% egg yolk) extenders, using nine ejaculates from three stallions chilled for up to 96 h. Subsequently, the effect of 25 mM LC supplementation (the optimal concentration) on chilling (INRA-96) and freezing (INRA-Freeze®) extenders was evaluated using eight pooled samples from sixteen ejaculates (2 ejaculates/pool) from four stallions. Results indicated that all LC concentrations produced significantly higher values (P<0.05) for kinematic variables (total [TM] and progressive motilities, curvilinear [VCL] and straight-line [VSL] velocity, and beat-cross frequency [BCF]), and the integrity of plasma/acrosome membranes (IPIA) compared to non-supplemented chilled sperm samples for up to 96 h with both extenders. Moreover, the use of 25 mM LC was more efficient (P<0.05) in preserving the post-chilled values of velocity, BCF, and IPIA for the long term than lower LC concentrations (1-10 mM). Post-thaw values of total motility, the amplitude of lateral head displacement (ALH), and IPIA were significantly improved (P<0.05) when INRA-Freeze extender was supplemented with 25 mM LC. In conclusion, supplementation of l-carnitine to skimmed milk-based extenders enhanced kinematic variables and protected the membrane integrity in chilled and frozen-thawed Peruvian Paso horse spermatozoa.

Advancements in Understanding and Enhancing Antioxidant-Mediated Sperm Cryopreservation in Small Ruminants: Challenges and Perspectives

Cryopreservation poses significant challenges to the preservation of sperm integrity and function, particularly in small ruminants where cryodamage is pronounced. This review explores the molecular mechanisms underlying sperm cryodamage and strategies for improving cryopreservation outcomes, with a focus on the role of antioxidants. Cryopreservation-induced alterations in proteins and RNA transcripts critical for sperm function, including motility, capacitation, fertilization, and embryo development, are discussed. Proteomic, transcriptomic, and epigenomic advancements have provided valuable insights into these mechanisms, offering potential biomarkers for predicting sperm freezability and enhancing cryopreservation strategies. Combining technologies such as mass spectrometry and flow cytometry allows for a comprehensive understanding of molecular and cellular changes induced by the freezing-thawing process. However, challenges remain in optimizing cryoprotectant formulations and antioxidant supplementation to improve post-thaw sperm fertility. Further research is needed to explore a wider range of novel cryoprotectants, antioxidants, and proteins for cryopreservation media, as well as to validate their efficacy in enhancing sperm viability and function. Additionally, investigations into the effects of cryopreservation on RNA transcripts and epigenetic factors in small ruminant species are warranted to advance our understanding of sperm preservation. Overall, this review highlights the importance of antioxidants in mitigating cryodamage and underscores the need for continued research to refine cryopreservation protocols and improve reproductive outcomes in small ruminants.

The influence of oral antioxidants on men with infertility: a systemic review

OBJECTIVE

This study aims to investigate the current evidence regarding the impact of oral antioxidant supplementation on semen parameters of infertile men.

MATERIALS AND METHODS

We conducted a systematic search of PubMed, and Cochrane electronic databases, adhering to modified Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines. The focus was on studies exploring the effects of antioxidant therapy on infertile men, with an examination of antioxidants in terms of types, doses, rationale for use, and their impact on semen parameters measures.

RESULTS

A total of 18 studies that met the inclusion criteria were included in this study. Out of these, 14 studies reported a significantly positive influence of antioxidant therapy on basic semen parameters and advanced sperm function. These comprised 11 randomized clinical trials and 7 prospective studies. Commonly utilized antioxidants included Vitamin E, Vitamin C, carnitines, co-enzyme Q10, N-acetyl cysteine, zinc, selenium, folic acid, and lycopene.

CONCLUSIONS

Overall, antioxidants generally demonstrate a favorable effect on semen parameters of infertile men. However, further research is necessary to pinpoint the optimal antioxidant regimen that can be applied safely and effectively in clinical practice.

Oxidative Stress and Male Infertility: The Protective Role of Antioxidants

Oxidative stress is a significant factor in male infertility, compromising sperm function and overall reproductive health. As male infertility garners increasing attention, effective therapeutic interventions become paramount. This review investigates the therapeutic role of antioxidants in addressing male infertility. A detailed examination was conducted on antioxidants such as vitamin C, E, B12, D, coenzyme Q10, zinc, folic acid, selenium, l-carnitine, l-arginine, inositols, and alpha-lipoic acid. This analysis examines the methodologies, outcomes, and constraints of current clinical studies. Antioxidants show notable potential in counteracting the negative effects of oxidative stress on sperm. Based on the evidence, these antioxidants, individually or synergistically, can enhance sperm health and reproductive outcomes. However, certain limitations in the studies call for careful interpretation. Antioxidants are integral in tackling male infertility attributed to oxidative stress. The current findings underscore their therapeutic value, yet there's a pressing need for deeper, comprehensive research. Future studies should focus on refining dosage guidelines, identifying potential side effects, and discerning the most efficacious antioxidant combinations for male infertility solutions.

Seminal plasma untargeted metabolomic and lipidomic profiling for the identification of a novel panel of biomarkers and therapeutic targets related to male infertility

Male infertility occurs approximately in about 50% of all infertility cases and represents a serious concern worldwide. Traditional semen analysis alone is insufficient to diagnose male infertility. Over the past two decades, advances in omics technologies have led to the widespread application of metabolomics profiling as a valuable diagnostic tool for various diseases and disorders. Seminal plasma represents a rich and easily accessible source of metabolites surrounding spermatozoa, a milieu that provides several indispensable nutrients to sustain sperm motility and fertilization. Changes of metabolic profiles in seminal plasma reflect male reproductive tract disorders. Here, we performed seminal plasma metabolomics and lipidomics profiling to identify a new pattern of biomarkers of male infertility. Seminal plasma samples from unfertile subjects (n = 31) and fertile controls (n = 19) were analyzed using an untargeted metabolomics/lipidomics integrated approach, based on Ultra-High-Pressure Liquid Chromatography-tandem Mass Spectrometry. Partial Least Squares-Discriminant Analysis showed a distinct separation between healthy fertile men and infertile subjects. Among the 15 selected candidate biomarkers based on Variable Importance in Projection scores, phosphatidylethanolamine (PE) (18:1; 18:1) resulted with the highest score. In total, 40 molecular species showed statistically significant variations between fertile and infertile men. Heat-map and volcano plot analysis indicated that acylcarnitines, phosphatidylserine (PS) (40:2) and lactate were decreased, while PE (18:1; 18:1), Phosphatidic acid (PA) (O-19:2; 18:1), Lysophosphatidylethanolamine (LPE) (O-16:1) and Phosphatidylcholine (PC) (O-16:2; 18:1)-CH3 were increased in the infertile group. The present study is the first one to analyze the metabolomics/lipidomics dysregulation in seminal plasma between fertile and infertile individuals regardless of sub-infertility condition. Association of several metabolites/lipids dysregulation with male infertility reinforced data of previous studies performed with different approaches. In particular, we confirmed significantly decreased levels of PS and carnitines in infertile patients as well as the positive correlation with sperm motility and morphology. If validated on a larger prospective cohort, the metabolite biomarkers of infertility in seminal plasma we identified in the present study might inform novel strategies for diagnosis and interventions to overcome male infertility.

Cryopreservation of tissues and organs: present, bottlenecks, and future

Tissue and organ transplantation continues to be an effective measure for saving the lives of certain critically ill patients. The organ preservation methods that are commonly utilized in clinical practice are presently only capable of achieving short-term storage, which is insufficient for meeting the demand for organ transplantation. Ultra-low temperature storage techniques have garnered significant attention due to their capacity for achieving long-term, high-quality preservation of tissues and organs. However, the experience of cryopreserving cells cannot be readily extrapolated to the cryopreservation of complex tissues and organs, and the latter still confronts numerous challenges in its clinical application. This article summarizes the current research progress in the cryogenic preservation of tissues and organs, discusses the limitations of existing studies and the main obstacles facing the cryopreservation of complex tissues and organs, and finally introduces potential directions for future research efforts.

Human Sperm as an In Vitro Model to Assess the Efficacy of Antioxidant Supplements during Sperm Handling: A Narrative Review

Spermatozoa are highly differentiated cells that produce reactive oxygen species (ROS) due to aerobic metabolism. Below a certain threshold, ROS are important in signal transduction pathways and cellular physiological processes, whereas ROS overproduction damages spermatozoa. Sperm manipulation and preparation protocols during assisted reproductive procedures-for example, cryopreservation-can result in excessive ROS production, exposing these cells to oxidative damage. Thus, antioxidants are a relevant topic in sperm quality. This narrative review focuses on human spermatozoa as an in vitro model to study which antioxidants can be used to supplement media. The review comprises a brief presentation of the human sperm structure, a general overview of the main items of reduction-oxidation homeostasis and the ambivalent relationship between spermatozoa and ROS. The main body of the paper deals with studies in which human sperm have been used as an in vitro model to test antioxidant compounds, including natural extracts. The presence and the synergic effects of different antioxidant molecules could potentially lead to more effective products in vitro and, in the future, in vivo.

Sperm cryopreservation: current status and future developments

The cryopreservation of spermatozoa is an important reproductive technology for the preservation of fertility in man and animals. Since the serendipitous discovery of glycerol as an effective cryoprotectant in 1947, sperm cryopreservation has undergone many changes in terms of the freezing methods employed, the rates at which samples are frozen and thawed, and the media used to preserve sperm functionality and DNA integrity. An extensive literature survey has been conducted addressing the cryoprotectants employed for both animal and human semen and the freezing protocols utilised. The results indicate that glycerol remains the dominant cryoprotective agent, usually incorporated into a balanced salt solution containing energy substrates, buffers, osmolytes and protein in the form of human serum albumin (human) or skimmed milk (animal). Realisation that some of the damage observed in cryostored cells involves the generation of reactive oxygen species during the thawing process, has prompted many studies to assess the relative merits of incorporating antioxidants into the cryopreservation media. However, in the absence of systematic comparisons, there is currently no consensus as to which antioxidant combination might be the most effective. Utilising our fundamental understanding of cryodamage to optimise cryopreservation protocols for each species will be important in the future.

Effects of dietary carnitine supplementation on semen output and quality of boars

Carnitine is an amino acid derivative that performs the functions of increasing energy production as well as acting as an antioxidant for sperm cells. This study was conducted to investigate the effects of the inclusion of carnitine in boar diets on semen output and quality. Sixty-four purebred and hybrid boars at a commercial boar stud were blocked by age and semen quality and randomly allotted to receive a daily 30 g top-dress of either soybean meal (CON) or soybean meal and 625 mg of L-Carnitine (CARN). Supplementation lasted for 12 weeks from May to July 2021 during which weekly semen collection was performed. Semen was evaluated in the stud for concentration and motility parameters using computer-assisted semen analysis (CASA). Samples were shipped to Purdue University for detailed morphology, viability, and CASA analysis performed in samples stored at 17 °C for 5 days. PROC Mixed (SAS v 9.4) was used to analyze data, with boar nested within treatment used in repeated measures analysis. Semen quality estimates from the week before supplementation were used as covariates in the statistical model. Tukey–Kramer adjustment was used for means separation. Carnitine supplementation had no effects on total sperm produced (P = 0.35). Percentage of motile sperm cells (P = 0.63), morphologically normal sperm (P = 0.42), viable sperm (P = 0.43), or sperm with normal acrosomes (P = 0.61) in the ejaculates were not different among treatments. Sperm kinematics in CARN ejaculates tended to have greater straight-line velocity and distance (P = 0.06 and P = 0.07, respectively). There were several interactions of treatment and day of storage for the kinematic parameters. However, these interactions do not show observable trends for CARN to improve or depress sperm function. Overall, the inclusion of 625 mg/d of carnitine in the diet of boars for 12 weeks had no effects on sperm output or quality with minor changes to sperm cell kinematics.

Restoring Sperm Quality Post-Cryopreservation Using Mitochondrial-Targeted Compounds

While critical for male fertility preservation, cryopreservation damage reduces sperm quality and fertilization potential. This study investigated whether the addition of mitochondrial-targeted, antioxidant compounds, also known as Mitochondrial activators, to the cryopreservation medium could protect sperm quality during cryopreservation. For this, semen samples from men undergoing IVF/ICSI treatment, which were donated for research, underwent cryopreservation in the absence or presence of BGP-15, MitoQ and L-carnitine. Fresh semen and thawed sperm samples from the same participant were analyzed for indicators of sperm quality: sperm viability, kinetics, mitochondrial reactive oxygen species (ROS) levels, Mitochondrial Membrane Potential (MMP) and DNA damage. Cryopreservation significantly reduced sperm viability and motility and predicted mucous penetration. BGP-15, MitoQ and L-carnitine improved sperm motility, whilst the addition of L-Carnitine prevented the loss of sperm viability during cryopreservation. Both BGP-15 and L-carnitine reduced sperm DNA oxidative damage, but only BGP-15 significantly reduced DNA fragmentation. More importantly, BGP-15 increased sperm predictive mucous penetration and MMP and reduced DNA oxidation. Our results show that the addition of BGP-15 or L-carnitine to the cryopreservation medium improves sperm quality post-thawing, highlighting the potential of mitochondrial antioxidants to improve long-term fertility preservation in males.

The relationship between reactive oxygen species, DNA fragmentation, and sperm parameters in human sperm using simplified sucrose vitrification with or without triple antioxidant supplementation

Objective

This study examined whether the addition of triple antioxidants (3A)—10 µM acetyl-L-carnitine, 10 µM N-acetyl-L-cysteine, and 5 µM α-lipoic acid—in freezing-thawing medium during human sperm cryopreservation using the sucrose vitrification (SuV) and liquid nitrogen vapor (Vapor) techniques could improve post-thaw survival of spermatozoa.

Methods

We analyzed 30 samples from healthy human sperm donors. Each sample was allocated into one of five groups: fresh control, SuV, SuV+3A, Vapor, and Vapor+3A. The sperm motility, morphology, viability, intracellular and extracellular reactive oxygen species (ROS) levels, and sperm DNA fragmentation (SDF) were evaluated.

Results

The cryopreserved spermatozoa had significantly reduced percentages of motility (p<0.05) and viability (p<0.05). Antioxidant supplementation non-significantly improved these parameters (p>0.05). No significant differences were found in sperm morphology between the fresh and frozen-thawed groups (p>0.05). After freezing, the extracellular ROS levels in the frozen-thawed groups were significantly higher (p<0.05) than in the fresh group. However, we did not find any differences in intracellular ROS parameters among these groups (p>0.05). The SDF was higher in the SuV and Vapor groups than in the fresh group, but without statistical significance (p=0.075 and p=0.077, respectively).

Conclusion

Cryopreservation had detrimental effects on sperm motility, viability, and extracellular ROS levels, without changing the morphology or intracellular ROS levels. Antioxidant supplementation was slightly effective in preventing SDF in frozen-thawed spermatozoa.

Age-Related Decline of Male Fertility: Mitochondrial Dysfunction and the Antioxidant Interventions

Mitochondria are structurally and functionally unique organelles in male gametes. Apparently, as the only organelles remaining in mature sperm, mitochondria not only produce adeno-sine triphosphate (ATP) through oxidative phosphorylation (OXPHOS) to support sperm mobility, but also play key roles in regulating reactive oxidation species (ROS) signaling, calcium homeostasis, steroid hormone biosynthesis, and apoptosis. Mitochondrial dysfunction is often associated with the aging process. Age-dependent alterations of the epididymis can cause alterations in sperm mitochondrial functioning. The resultant cellular defects in sperm have been implicated in male infertility. Among these, oxidative stress (OS) due to the overproduction of ROS in mitochondria may represent one of the major causes of these disorders. Excessive ROS can trigger DNA damage, disturb calcium homeostasis, impair OXPHOS, disrupt the integrity of the sperm lipid membrane, and induce apoptosis. Given these facts, scavenging ROS by antioxidants hold great potential in terms of finding promising therapeutic strategies to treat male infertility. Here, we summarize the progress made in understanding mitochondrial dysfunction, aging, and male infertility. The clinical potential of antioxidant interventions was also discussed.

The Effect of Semen Cryopreservation Process on Metabolomic Profiles of Turkey Sperm as Assessed by NMR Analysis

Semen cryopreservation represents the main tool for preservation of biodiversity; however, in avian species, the freezing−thawing process results in a sharp reduction in sperm quality and consequently fertility. Thus, to gain a first insight into the molecular basis of the cryopreservation of turkey sperm, the NMR-assessed metabolite profiles of fresh and frozen−thawed samples were herein investigated and compared with sperm qualitative parameters. Cryopreservation decreased the sperm viability, mobility, and osmotic tolerance of frozen−thawed samples. This decrease in sperm quality was associated with the variation in the levels of some metabolites in both aqueous and lipid sperm extracts, as investigated by NMR analysis. Higher amounts of the amino acids Ala, Ile, Leu, Phe, Tyr, and Val were found in fresh than in frozen−thawed sperm; on the contrary, Gly content increased after cryopreservation. A positive correlation (p < 0.01) between the amino acid levels and all qualitative parameters was found, except in the case of Gly, the levels of which were negatively correlated (p < 0.01) with sperm quality. Other water-soluble compounds, namely formate, lactate, AMP, creatine, and carnitine, turned out to be present at higher concentrations in fresh sperm, whereas cryopreserved samples showed increased levels of citrate and acetyl-carnitine. Frozen−thawed sperm also showed decreases in cholesterol and polyunsaturated fatty acids, whereas saturated fatty acids were found to be higher in cryopreserved than in fresh sperm. Interestingly, lactate, carnitine (p < 0.01), AMP, creatine, cholesterol, and phosphatidylcholine (p < 0.05) levels were positively correlated with all sperm quality parameters, whereas citrate (p < 0.01), fumarate, acetyl-carnitine, and saturated fatty acids (p < 0.05) showed negative correlations. A detailed discussion aimed at explaining these correlations in the sperm cell context is provided, returning a clearer scenario of metabolic changes occurring in turkey sperm cryopreservation.

A narrative review on the research progress of gonadal function protection in children with cancer

Background and Objective

The global incidence of malignant tumors in children (0-14 years) and adolescents (15-19 years) ranges between 95 per 1 million and 255 per 1 million, which seriously affects the survival of patients. In the past 30 years, with the application of comprehensive treatments (including surgery, chemotherapy, radiotherapy, and bone marrow transplantation), great progress has been made in the treatment of malignant tumors in children and adolescents. The 5-year survival rate now exceeds 80%, and most patients can smoothly enter adolescence or the reproductive period. However, due to the particular age of patients with malignant tumors in children and adolescents, treatment may cause abnormal growth of the patient's height, bones, and some vital organs (such as the pituitary gland and reproductive organs). Treatment may also cause abnormal secretion of growth hormones, thyroid hormones, and sex hormones. These complications seriously affect the quality of life of tumor patients. In the past ten years, countries have established long-term follow-up specifications for children with tumors. These programs have found that, in adulthood, 67% to 75% of children who survived having tumors have at least one treatment-related complication. Among patients receiving chemotherapy, gonadal dysfunction is the most common related endocrine dysfunction.

Methods

This paper reviews the literature on fertility protection services for cancer patients in foreign countries was conducted to provide a reference for developing gonadal protection services for cancer patients and for establishing consensus or guidelines on gonadal protection in China.

Key Content and Findings

In the treatment of childhood cancer, the assistance of reproductive technology can effectively reduce the occurrence of complications from treatment.

Conclusions

Therefore, minimizing the effects of radiotherapy and chemotherapy on the growth and endocrine of children and adolescents while treating tumors is a new challenge for oncologists.

Comparative Potential of Zinc Sulfate, L-Carnitine, Lycopene, and Coenzyme Q10 on Cadmium-Induced Male Infertility

The human exposure to toxic chemicals and heavy metals is one of the main predisposing factors contributing to male infertility. Acute exposure to cadmium chloride results in testicular damage and infertility. The purpose of the present study was to investigate and compare the curative effect of coenzyme Q10 (CoQ10), lycopene, L-carnitine (LC), and zinc sulfate against the cadmium-induced infertility in male Wistar rats. Cadmium chloride (0.4 mg/kg/day) was orally administered to rats for three consecutive days. Then, oral administration of different treatments (i.e., LC 100 mg/kg, CoQ10 20 mg/kg, lycopene 4 mg/kg, zinc sulfate 6 mg/kg, and a combination LC-CoQ10 at 500/50 mg/kg) was carried out for 30 days. The impact of different treatments on semen parameters, such as sperm count and motility, testicular antioxidants, and serum testosterone, was determined. Furthermore, the morphology of epididymis sperms and histopathology of rat testes were also assessed. Cadmium exposure decreased the sperm count, progressive sperm motility, testosterone, superoxide dismutase (SOD), and catalase and reduced glutathione (GSH). It also caused banana sperm tail, bent sperm head, vacuolization of seminiferous tubules, and oligospermia in rat testes. All treatments with nutraceuticals improved sperm count, sperm morphology, serum testosterone, vacuolization of seminiferous tubules, and oligospermia in diseased rats. Treatment with lycopene, LC, and LC-CoQ10 improved progressive sperm motility and other parameters and increased SOD, GSH, and CAT in the rat testes. CoQ10 also increased SOD activity in rat testes' tissue homogenates. It is concluded from the current study that all nutraceuticals partially improved reproductive toxicity of cadmium. The administration of lycopene and a high-dose combination of LC-CoQ10 were more efficacious in treating cadmium-induced infertility than other treatments. Treatment of cadmium-exposed rats with lycopene, LC, CoQ10, and LC-CoQ10 improved sperm count and motility through reduction of testicular oxidative stress and improving serum testosterone.

Addition of l-carnitine to the freezing extender improves post-thaw sperm quality of Okinawan native Agu pig

The objective of the present study was to establish whether the addition of l-carnitine (LC), which exhibits antioxidant activity, to the freezing extender improves the quality of cryopreserved Okinawan native Agu pig sperm. Ejaculated sperm frozen in an extender supplemented with 0, 1, 2.5, or 5 mM LC was thawed, and the integrities of mitochondria and the plasmalemma and other sperm characteristics were evaluated. The treatment with different concentrations of LC effectively improved sperm motility, mitochondrial and plasmalemmal integrities, and the proteolytic activity of acrosomal contents after freeze-thawing (P < 0.05). The proportion of post-thaw sperm possessing intact mitochondria and plasmalemma and higher proteolytic activity of acrosomal contents was markedly higher among sperm frozen in the presence of 2.5 mM LC than among sperm frozen in the extender without LC (P < 0.05). Furthermore, although the addition of LC to the freezing extender had no effect on disturbance of DNA damage and caspase activity, sperm treated with 2.5 mM LC during freezing exhibited significantly higher penetrability into matured oocytes in vitro than untreated sperm. Collectively, these results indicate that the addition of LC to the freezing extender effectively improved the post-thaw quality of Agu pig sperm by preventing mitochondrial dysfunction caused by oxidative stress during cryopreservation.

Role of Klotho as a Modulator of Oxidative Stress Associated with Ovarian Tissue Cryopreservation

Ovarian tissue cryopreservation is the only option for preserving fertility in adult and prepubertal cancer patients who require immediate chemotherapy or do not want ovarian stimulation. However, whether ovarian tissue cryopreservation can ameliorate follicular damage and inhibit the production of reactive oxygen species in cryopreserved ovarian tissue remains unclear. Oxidative stress is caused by several factors, such as UV exposure, obesity, age, oxygen, and cryopreservation, which affect many of the physiological processes involved in reproduction, from maturation to fertilization, embryonic development, and pregnancy. Here, freezing and thawing solutions were pre-treated with N-acetylcysteine (NAC) and klotho protein upon the freezing of ovarian tissue. While both NAC and klotho protein suppressed DNA fragmentation by scavenging reactive oxygen species, NAC induced apoptosis and tissue damage in mouse ovarian tissue. Klotho protein inhibited NAC-induced apoptosis and restored cellular tissue damage, suggesting that klotho protein may be an effective antioxidant for the cryopreservation of ovarian tissue.

The antioxidant roles of L-carnitine and N-acetyl cysteine against oxidative stress on human sperm functional parameters during vitrification

Objective

Amino acids can protect sperm structure in cryopreservation due to their antioxidant properties. Therefore, the present study aimed to investigate the protective effect of L-carnitine (LC) and N-acetyl cysteine (NAC) on motility parameters, plasma membrane integrity (PMI), mitochondrial membrane potential (MMP), DNA damage, and human sperm intracellular reactive oxygen species (ROS) during vitrification.

Methods

Twenty normal human sperm samples were examined. Each sample was divided into six equal groups: LC (1 and 10 mM), NAC (5 and 10 mM), and cryopreserved and fresh control groups.

Results

The groups treated with LC and NAC showed favorable findings in terms of motility parameters, DNA damage, and MMP. Significantly higher levels of intracellular ROS were observed in all cryopreserved groups than in the fresh group (p≤0.05). The presence of LC and NAC at both concentrations caused an increase in PMI, MMP, and progressive motility parameters, as well as a significant reduction in intracellular ROS compared to the control group (p≤0.05). The concentrations of the amino acids did not show any significant effect.

Conclusion

LC and NAC are promising as potential additives in sperm cryopreservation.

Supplementation of Avian Semen Extenders with Antioxidants to Improve Semen Quality-Is It an Effective Strategy?

Oxidative stress in sperm is a phenomenon related to the increasing rate of oxidation of cellular components and the excessive production of reactive oxygen species (ROS). The high content of polyunsaturated fatty acids in bird sperm cell membranes renders these cells particularly susceptible to lipid peroxidation (LPO). Therefore, to ensure the proper functioning of cells, it is necessary to have a balance between the formation of ROS and the protective action of the antioxidant system. This review aims firstly to briefly introduce the antioxidant system characteristics of avian semen. Secondly, we summarize the recent knowledge regarding progress in extender supplementation using antioxidants and other compounds to improve avian semen quality parameters and fertility rates. The review focuses on enzymes, vitamins, amino acids, proteins, some plant extracts, and other compounds that can be used to supplement the extenders to reduce the formation of oxidants in poultry semen and maintain its quality and enhance its fertility.

The Role of the Natural Antioxidant Mechanism in Sperm Cells

Molecular studies of the causes of male infertility revealed a significant contribution of oxidative stress. When excessive amounts of reactive oxygen species (ROS) are produced or antioxidant activity fails, the equilibrium between oxidation and reduction is disrupted, causing oxidative stress (OS). High levels of ROS can have an adverse effect on sperm function through the initiation of DNA damage, lipid peroxidation, loss of membrane integrity and increased permeability, inactivation of cellular enzymes, and cell apoptosis. In addition to endogenous factors such as immature sperm, leukocytes, and varicocele, potential causes of excessive ROS can also be found exogenously in males with testicular hyperthermia or exposed to environmental toxicity. To maintain the optimal functioning of sperm cells, it is, therefore, necessary to balance the redox potential, i.e., to balance ROS by antioxidants. The purpose of this review is to present the antioxidant defense systems in semen.

Protective effects of hesperetin on the quality of sperm, apoptosis, lipid peroxidation, and oxidative stress during the process of cryopreservation: An experimental study

BACKGROUND

Hesperetin is a bioflavonoid compound, largely used in Chinese traditional medicine and found plenty in citrus fruits. Hesperetin has beneficial effects against different diseases. The sperm cryopreservation process is a common method that is used in infertility laboratories. It has been reported that during the cryopreservation process, the quality of sperm is significantly reduced.

OBJECTIVE

To investigate the effect of hesperetin on the quality of human spermatozoa during the cryopreservation process.

MATERIALS AND METHODS

In this experimental study, 22 sperm sample of normozoospermia men who reffered to the infertility department of the Shariati Hospital (Tehran, Iran) Between October and November 2019 were collect and divided in to three groups as: 1) fresh, 2) control (frozen-thawed group without treatment), and 3) treatment group as frozen-thawed samples supplemented with 20 µM hesperetin. Motility, Viability, morphology, Apoptotic-like changes, intracellular H2 O2 , intracellular O2- , and lipid peroxidation (LPO) was measured.

RESULTS

Hesperetin treatment during the cryopreservation process of human sperm significantly improved the viability, motility, and morphology rates of the spermatozoa after frozen-thawed process in control group (p < 0.01). In addition, it significantly reduced the reactive oxygen species (ROS) level, LPO level and increased the percentage of viable sperm cells with intact plasma membrane (p < 0.01) after frozen-thawed process.

CONCLUSION

Hesperetin can improve the quality of human sperm and also protect human sperm against reactive oxygen species, LPO, and apoptosis during the cryopreservation-thawing process.

Testicular transcriptome analysis under the dietary inclusion of l-carnitine reveals potential key genes associated with oxidative defense and the semen quality factor in aging roosters

l-carnitine (LC) has been widely studied as a natural antioxidant molecule for treating low-fertility gametes. However, the molecular mechanism of the effect of LC supplementation on the testes of aging cocks has not been evaluated. Therefore, the objective of this study was to reveal the mechanism of testicular oxidative defense induced by LC supplementation in relation to the semen quality factor (SQF) in the aging cock through a transcriptome study conducted from a new perspective. A total of 24 Jinghong cocks at 55 wk of age were randomly divided into 2 groups (n = 12). All cocks were fed a standard isocaloric and isonitrogenic breeder diet (control, LC-0), and the other group was supplemented with LC at 150 mg/kg/d (treated, LC-150) for 12 wk. Remarkably, seminal characteristics and enzymes, sex hormones, and cock fertility related to testicular oxidative defense were considerably improved by LC supplementation. LC-150 testes showed the differential upregulation and downregulation of 97 and 90 transcripts, respectively, compared with LC-0 testes. Most upregulated transcripts were involved in testicular oxidative defense and spermiogenesis optimization, whereas the downregulated genes were responsible for oxidative stress, in contrast to the SQF. Functional analysis of the transcriptionally altered genes indicated the testicular deregulation of long-chain fatty acid and lipid peroxidation, enhancing fatty acid breakdown to release ATP production via β-oxidation. These findings could lay the foundation for the discovery of new molecular markers of SQF-associated LC supplementation and potential targets for therapeutic intervention to optimize fertility in aging cocks.

l-carnitine and l-acetylcarnitine supplementation for idiopathic male infertility

Fifteen percent of couples are globally estimated to be infertile, with up to half of these cases attributed to male infertility. Reactive oxidative species (ROS) are known to damage sperm leading to impaired quantity and quality. Although not routinely assessed, oxidative stress is a common underlying pathology in infertile men. Antioxidants have been shown to improve semen analysis parameters by reducing ROS and facilitating repair of damage caused by oxidative stress, but it remains unclear whether they improve fertility. Carnitines are naturally occurring antioxidants in mammals and are normally abundant in the epididymal luminal fluid of men. We conducted a systematic review and meta-analysis to evaluate the safety and efficacy of carnitine supplementation for idiopathic male infertility. We searched ClinicalKey, ClinicalTrials.gov, Cochrane Central Register of Controlled Trials (CENTRAL), EMBASE, MEDLINE, PubMed and ScienceDirect for relevant studies published from 1 January 2000 to 30 April 2020. Of the articles retrieved, only eight randomised controlled trials were identified and included. Analysis showed that carnitines significantly improve total sperm motility, progressive sperm motility and sperm morphology, but without effect on sperm concentration. There was no demonstrable effect on clinical pregnancy rate in the five studies that included that outcome, although patient numbers were limited. Therefore, the use of carnitines in male infertility appears to improve some sperm parameters but without evidence of an increase in the chance of natural conception.

Dietary supplements in the management of varicocele-induced infertility: A review of potential mechanisms

Varicocele is a main cause of lower production of spermatozoon and infertility with multiple pathophysiological mechanisms. In the past decades, the use of dietary supplements has significantly increased due to both the modern lifestyle and the food shortages of the industrialised countries. The purpose of this review paper is to collect scientific evidences from basic and clinical studies which support the use of dietary supplements to define the clinical framework for patients with varicocele. In the present review, we used keywords such as dietary supplements, varicocele, male infertility, oxidative stress, DNA fragmentation, sperm parameters to find the proper articles. The standard search biomedical engines were used for seeking the papers. The use of dietary supplements such as minerals, vitamins and antioxidants has an essential role in the prevention and treatment of varicocele by increasing the levels of antioxidant enzymes (e.g. peroxidase, superoxide dismutase and catalase) and decreasing the levels of inflammatory markers (e.g. tumour necrosis factor-α, interleukin-6 and interleukin-1) in testis. According to the results, the dietary supplements may alleviate the spermatogenesis in varicocele patients through different mechanisms such as suppression of stress oxidative and inflammation in testicular tissue.

L-carnitine as primary or adjuvant treatment in infertile patients with varicocele. A systematic review

BACKGROUND

Varicocele has been found to impair the function of the epididymis resulting in subfertility whereas the varicocelectomy can resolve the phenomenon. L-carnitine is regarded as a biomarker for the function of the epididymis and has been found in reduced concentrations in infertile patients of various causes, including infertile men with varicocele. It seems that Lcarnitine and varicocele share clinical significance and the area of research looks promising.

OBJECTIVE

To identify the role of L-carnitine in the treatment of varicocele.

MATERIALS AND METHODS

A systematic search was performed in Pubmed/Medline with the terms (L-carnitine) and (varicocele) and (L-carnitine) and (varicocelectomy). Inclusion criteria were studies reported outcomes of L-carnitine administration alone or in duet, as primary or adjuvant treatment to varicocele. Exclusion criteria were non-English language and animal studies. Studies using L-carnitine as part of a panel of therapeutic agents were avoided.

RESULTS

Only four suitable studies were identified for discussion. In one randomized study, the combination of L-carnitine and cinnoxicam improved semen parameters in patients with non-high-grade varicocele compared to L-carnitine alone and had a favourable effect on pregnancy rates but the effect of grade is unknown. In another study, as an adjuvant treatment to varicocelectomy, L-carnitine showed no clear benefit. Finally, in comparison to surgery, the results are inconclusive; two studies showed some benefit might be expected in low-grade or subclinical varicocele, but surgery appears superior.

CONCLUSIONS

The evidence regarding the role of L-carnitine as a primary or adjuvant treatment of varicocele is sparse. The pathophysiological significance of L-carnitine implicates a potential role of the molecule in the management of varicocele, but the evidence so far is controversial for any recommendations. L-carnitine might be taken into consideration in selected cases; however, further search is needed in order the optimal role of L-carnitine in infertile patients with varicocele to be clarified.

Effects of L-Carnitine on Equine Semen Quality During Liquid Storage

l-Carnitine (LC) plays a key role in sperm metabolism, easily providing energy through β-oxidation, which positively affects motility. The objective of this study was to investigate the association between blood plasma and seminal plasma LC levels, as well as the effect of LC as an additive in a skimmed milk-based extender during sperm storage at 5°C. In the first experiment, semen and blood samples from 14 Quarter Horse stallions were used. The LC content in blood plasma and seminal plasma was determined by spectrophotometry and their relationships with seminal parameters were evaluated. In the second experiment, ejaculates (n = 16) from four Quarter Horses were used. Each ejaculate was split into four treatment groups with different LC concentrations: 0 (control), 0.5, 1.0, and 2.0 mM. Sperm motility, integrity of plasma and acrosomal membranes, intracellular reactive oxygen species content, and plasma membrane stability were evaluated immediately after samples reached 5°C (0 hour) and after 24, 48, and 72 hours. There was a positive correlation (p < 0.05) between LC levels in seminal plasma with both sperm concentration and plasma and acrosomal membrane integrity. Furthermore, the addition of LC (1 and 2 mM) preserved the motility of equine sperm stored at 5°C. It was concluded that the concentrations of LC with seminal plasma present correlate to semen parameters and the addition of LC to skimmed milk-based extender preserves the motility of equine sperm stored at 5°C for up to 48 hours.

The Effects of Calligonum Extract and Low-Intensity Ultrasound on Motility, Viability, and DNA Fragmentation of Human Frozen-Thawed Semen Samples

Background

The study aimed to evaluate the impact of Calligonum extract and US radiation on sperm parameters of cryopreserved human semen samples.

Materials and Methods

In this experimental study, twenty-five semen specimens were obtained from healthy semen donors and incubated in human tubal fluid (HTF) medium supplemented with 10% human serum albumin (HSA) for 45 minutes. Samples were treated with Calligonum extract (10 μg/ml) alone (CGM group) and US radiation (LIPUSexposed group) alone or a combination of both treatments (CGM+LIPUS). The US group received US stimulation (in both continuous and pulsed wave modes) at a frequency of 1 MHZ and intensity of 200 mW/cm2 for 200 seconds. Sperm morphology was assessed by Diff-Quik staining. The DNA fragmentation was evaluated the Halo sperm kit. Sperm parameters was analyzed by a computer-assisted semen analysis system. Reactive oxygen species (ROS) was assessed by flow cytometry.

Results

The results showed that the treatment with Calligonum extract significantly (P<0.05) increased the progressive motility of spermatozoa in the CGM group as compared with the control group. The application of low-intensity US significantly (P<0.05) decreased the motility and viability of spermatozoa in the US group when compared with the control group. Our findings also indicated that the use of both low-intensity US in continuous mode and Calligonum extract slightly increased progressive motility; however, such an increase was not statistically significant. The rate of DNA fragmentation was considerably higher (P<0.05) in control and LIPUS-exposed groups than the other groups.

Conclusion

Treatment of spermatozoa with Calligonum extract slightly improved the sperm parameters due to its antioxidant activity, on the other hand, according to our results, US radiation did not improve sperm parameters which may be due to interference with the motility of sperm, as well as its physical effects on spermatozoa.

Endogenous and Exogenous Antioxidants As a Tool to Ameliorate Male Infertility Induced by Reactive Oxygen Species

Significance: Antioxidants are essential for the maintenance of cellular redox homeodynamics in the male reproductive tract, playing a key role in fertilizing potential. Reactive oxygen species (ROS), at physiological levels, are essential for sperm function and fertilization. Under pathological conditions, abnormal production of ROS may occur. Redox control is primarily regulated by the inner antioxidant system. However, these endogenous antioxidants may be present at abnormal amounts or may be insufficient. Exogenous antioxidants obtained through the diet may have an important role, particularly in specific pathological conditions. This review addresses the regulation of redox homeodynamics in the male reproductive tract by endogenous and exogenous antioxidants and the importance of their cooperation for the maintenance of fertility. Recent Advances: Many studies have shown the importance of antioxidants for the preservation of male fertility, mostly under pathological conditions. Excessive antioxidants can inhibit ROS-induced signaling pathways that are essential for the reproductive system. The challenge is to keep the balance between oxidants and antioxidants to maintain ROS-amount at physiological concentration. Critical Issues: Although antioxidant therapies are gaining popularity and showing promising results in the improvement of male fertility, there is a lack of knowledge regarding the type of exogenous antioxidant, the doses and time to be administered. Future Directions: It would be of great importance to find a way to restore redox homeostasis under stress conditions. Understanding the poorly studied mechanisms by which exogenous antioxidants cooperate with the inner cellular antioxidant system to counteract free radicals may help in the development of new fertility therapies.

Acrosome and chromatin integrity, oxidative stress, and expression of apoptosis-related genes in cryopreserved mouse epididymal spermatozoa treated with L-Carnitine

Oxidative stress is believed to be an important cause of sperm damage during freezing. l-Carnitine (LC) may have the potential to improve sperm quality after frozen-thawed process. The present study aimed to investigate the effect of LC supplementation in cryoprotectant media of mouse epididymal sperm on post-thaw sperm quality and expression of apoptosis-related genes. Male BALB/cJ mice spermatozoa were cryopreserved in a cryoprotectant medium containing 2.5 or 5 mM LC. The untreated group was cryopreserved with the cryoprotectant medium only. Six months following cryopreservation, the samples were thawed and sperm quality parameters, chromatin and acrosome integrity, reactive oxygen species (ROS) and glutathione (GSH) levels, mitochondrial activity, and mRNA expression of Bax and Bcl-2 were assessed. The results demonstrated that the concentration of 5 mM LC in cryoprotectant media exhibited higher values for the sperm quality parameters and integrity of chromatin and acrosome in post-thaw spermatozoa than those of the untreated group. Furthermore, sperm ROS levels decreased while GSH and mitochondrial activity levels increased in 5 mM LC group compared to those in the untreated group (P < 0.01). In 5 mM LC-treated group, Bax was down-regulated (P < 0.05) while Bcl-2 was up-regulated (P < 0.001) compared to the untreated group. Collectively, LC supplementation of cryoprotectant medium improved the quality of frozen-thawed mouse epididymal spermatozoa, as showed reduced ROS level and Bax expression as well as increased GSH, mitochondrial activity, and Bcl-2 expression.

The efficacy of antioxidants in sperm parameters and production of reactive oxygen species levels during the freeze-thaw process: A systematic review and meta-analysis

To investigate the impact of antioxidants in sperm parameters and reduction in reactive oxygen species production during the freeze-thaw process. PubMed, Scopus, Web of Science, Embase and Cochrane central library were systematically searched. Of the 1583 articles, 23 studies were selected for data extraction. Our results show that antioxidants improved sperm progressive motility (standardised mean difference (SMD) = 1; 95% CI: 0.62, 1.38; p < .001) and viability (SMD = 1.20; 95% CI: 0.50, 1.91; p = .001) and reduced sperm DNA fragmentation (SDF) and hydrogen peroxide (H₂ O₂ ) production, but there was no significant improvement in total sperm motility after thawing. Acetyl-l-carnitine/l-carnitine, melatonin and catalase had a significant positive impact on progressive motility. The role of tempol and melatonin in improving viability was significant compared to other antioxidants. Moreover, a significant reduction in SDF was observed after addition of butylated hydroxytoluene, tempol and vitamin E. However, the prevention of H₂ O₂ production was significant only after the addition of tempol. Our overall results displayed the positive impact of antioxidants on progressive sperm motility, viability and reduction in SDF and H₂ O₂ production, but no significant impact of antioxidants on total sperm motility was seen during the freeze-thaw process.

The influence of l-carnitine on the expression of miRNAs in asthenospermia spermatozoa and the network regulation of the associated molecules

l-carnitine is a natural compound that is indispensable for energy metabolism in mammals. The efficiency and safety of l-carnitine in improving sperm activity, enhancing epididymal function and treating male infertility has been widely acknowledged by clinicians. CircRNAs can regulate gene expression at the transcriptional or post-transcriptional level by serving as a molecular sponge of miRNAs with miRNA response elements. However, the detailed mechanism linking miRNA, circRNA and asthenospermia remains unclear. The present study demonstrated that hsa-miR-27b-3p, hsa-miR-151a-5p and hsa-miR-206 play an important role in the effects of l-carnitine treatment of the spermatozoa in asthenospermia patients. Furthermore, the target mRNAs of hsa-miR-206 were analysed by GO and KEGG. The results show that the target mRNAs of hsa-miR-206 may change the activity of ATP synthase and participate in the cAMP signalling pathway and the calcium signalling pathway, which may play an important role in sperm motility.

Cryopreservation of Sperm: Effects on Chromatin and Strategies to Prevent Them

Cryopreservation is a technique that can keep sperm alive indefinitely, enabling the conservation of male fertility. It involves the cooling of semen samples and their storage at -196 °C in liquid nitrogen. At this temperature all metabolic processes are arrested. Sperm cryopreservation is of fundamental importance for patients undergoing medical or surgical treatments that could induce sterility, such as cancer patients about to undergo genotoxic chemotherapy or radiotherapy, as it offers these patients not only the hope of future fertility but also psychological support in dealing with the various stages of the treatment protocols.Despite its importance for assisted reproduction technology (ART) and its success in terms of babies born, this procedure can cause cell damage and impaired sperm function. Various studies have evaluated the impact of cryopreservation on chromatin structure, albeit with contradictory results. Some, but not all, authors found significant sperm DNA damage after cryopreservation. However, studies attempting to explain the mechanisms involved in the aetiology of cryopreservation-induced DNA damage are still limited. Some reported an increase in sperm with activated caspases after cryopreservation, while others found an increase in the percentage of oxidative DNA damage. There is still little and contradictory information on the mechanism of the generation of DNA fragmentation after cryopreservation. A number of defensive strategies against cryoinjuries have been proposed in the last decade. Most studies focused on supplementing cryoprotectant medium with various antioxidant molecules, all aimed at minimising oxidative damage and thus improving sperm recovery. Despite the promising results, identification of the ideal antioxidant treatment method is still hampered by the heterogeneity of the studies, which describe the use of different antioxidant regimens at different concentrations or in different combinations. For this reason, additional studies are needed to further investigate the use of antioxidants, individually and in combination, in the cryopreservation of human sperm, to determine the most beneficial conditions for optimal sperm recovery and preservation of fertility.

The roles of reactive oxygen species and antioxidants in cryopreservation

Cryopreservation has facilitated advancement of biological research by allowing the storage of cells over prolonged periods of time. While cryopreservation at extremely low temperatures would render cells metabolically inactive, cells suffer insults during the freezing and thawing process. Among such insults, the generation of supra-physiological levels of reactive oxygen species (ROS) could impair cellular functions and survival. Antioxidants are potential additives that were reported to partially or completely reverse freeze-thaw stress-associated impairments. This review aims to discuss the potential sources of cryopreservation-induced ROS and the effectiveness of antioxidant administration when used individually or in combination.

Effect of different concentrations of l-carnitine in extender for semen cryopreservation in sheep

This study assessed the effect of l-carnitine (LC) in sheep semen extenders containing or not egg yolk for cryopreservation in sheep. Two extenders (TRIS-egg yolk or the commercial optiXcell™ IMV medium) were used, totaling six groups: IMV - (0, 5 and 10 mM LC) and TRIS - (0, 5 and 10 mM LC). After the freezing-thawing process and throughout incubation at 38 °C for up to 3 h, several parameters were evaluated: sperm kinetics, hypoosmotic, plasma membrane integrity, capacitation status and lipid peroxidation level. The supplementation of either 5 or 10 mM LC randomly affected some parameters and, overall, TRIS was superior (P < 0.05) than IMV extender. In the LC-groups, IMV had greater (P < 0.05) oxidative stress than TRIS. In conclusion, although LC affected isolated parameters, its supplementation in semen extender had no consistently beneficial effect on freezing-thawing ram sperm.

Human Semen Samples with High Antioxidant Reservoir May Exhibit Lower Post-Cryopreservation Recovery of Sperm Motility

Cryopreservation-thawing of human semen was found to reduce the level of antioxidant activity surrounding the sperm, which may negatively affect post-cryopreservation (post-thaw) recovery of sperm motility. Therefore, the current manufactured cryoprotectant media have been supplemented with certain antioxidants to preserve the loss in seminal antioxidant activity. In this study, we aimed to explore the correlation between total antioxidant capacity (TAC) of human semen samples before cryopreservation and the post-thaw recovery of sperm motility. Normal semen specimens (n = 77) were recruited in this study. Sperm motility was measured for each semen sample before and after cryopreservation and the post-thaw recovery of sperm motility was calculated. Seminal TAC was measured spectrophotometrically before cryopreservation for each semen sample using the sensitive cupric ion-reducing antioxidant capacity (CUPRAC) method. The results from this study showed that the post-thaw recovery of sperm motility is negatively correlated (p = 0.0404, p = 0.0402) with the absorbance at 450 nm and the values of seminal TAC in terms of µM Trolox equivalents, as evaluated by CUPRAC, respectively. In conclusion, the total antioxidant reservoir in each ejaculated semen specimen could be a factor in determining the post-thaw recovery of sperm motility toward lower recovery for semen specimens of high antioxidant content.

Sperm cryopreservation: A review on current molecular cryobiology and advanced approaches

The cryopreservation of spermatozoa was introduced in the 1960s as a route to fertility preservation. Despite the extensive progress that has been made in this field, the biological and biochemical mechanisms involved in cryopreservation have not been thoroughly elucidated to date. Various factors during the freezing process, including sudden temperature changes, ice formation and osmotic stress, have been proposed as reasons for poor sperm quality post-thaw. Little is known regarding the new aspects of sperm cryobiology, such as epigenetic and proteomic modulation of sperm and trans-generational effects of sperm freezing. This article reviews recent reports on molecular and cellular modifications of spermatozoa during cryopreservation in order to collate the existing understanding in this field. The aim is to discuss current freezing techniques and novel strategies that have been developed for sperm protection against cryo-damage, as well as evaluating the probable effects of sperm freezing on offspring health.

Recent advances in drug delivery via the organic cation/carnitine transporter 2 (OCTN2/SLC22A5)

INTRODUCTION

Transporters in the plasma membrane have been exploited successfully for the delivery of drugs in the form of prodrugs and nanoparticles. Organic cation/carnitine transporter 2 (OCTN2, SLC22A5) has emerged as a viable target for drug delivery. OCTN2 is a Na⁺-dependent high-affinity transporter for L-carnitine and a Na⁺-independent transporter for organic cations. OCTN2 is expressed in the blood-brain barrier, heart, liver, kidney, intestinal tract and placenta and plays an essential role in L-carnitine homeostasis in the body. Areas covered: In recent years, several studies have been reported in the literature describing the utility of OCTN2 to enhance the delivery of drugs, prodrugs and nanoparticles. Here we summarize the salient features of OCTN2 in terms of its role in the cellular uptake of its physiological substrate L-carnitine in physiological and pathological context; the structural requirements for recognition and the recent advances in OCTN2-targeted drug delivery systems, including prodrugs and nanoparticles, are discussed. Expert opinion: This transporter has great potential to be utilized as a target for drug delivery to improve oral absorption of drugs in the intestinal tract. It also has potential to facilitate the transfer of drugs across the biological barriers such as the blood-brain barrier, blood-retinal barrier, and maternal-fetal barrier.

Effects of L-Carnitine on the sperm parameters disorders, apoptosis of spermatogenic cells and testis histopathology in diabetic Rats

Background

Diabetes mellitus affects male reproductive system that is known to cause male infertility.

Objective

The aim of the present study was to assess the effects of L-carnitine (LC) on sperm parameters, apoptosis of spermatogenic cells and testis histopathology in Streptozotocin-induced diabetic Rats.

Materials and Methods

The study was carried out on 36 male Wistar adult rats (220 ± 30 gr) randomly divided into six groups (n = 6/each). 1 (Control); 2 (LC 100 mg/kg); 3 (Diabetic); 4, 5, and 6 (Diabetic + LC 50 or 100 or 200 mg/kg, respectively). Daily injections were administered intraperitoneally for 48 days. Then, rats were sacrificed, left testis and epididymis were harvested for sperm analysis and histopathology, morphometric and spermatogenesis assessments, and Tunnel assay.

Results

L-carnitine in group 6 significantly decreased blood glucose level (p < 0.01) in comparison with group 3. L-carnitine in groups 5 and 6 significantly (p < 0.001) and dose-dependently increased the count, motility, viability, maturity, and chromatin quality of sperm and decreased the abnormal morphology of sperm in comparison with group 3. In groups 4, 5, and particularly 6, in comparison with group 3, there has been a significant difference in the increase of seminiferous tubule diameter, germinal epithelium height (p < 0.001), maturity quality of the seminiferous tubules (p < 0.001), decrease apoptosis of spermatogenic cells (p < 0.001), and testis tissue histopathological complications.

Conclusion

The data obtained from the present study suggest that in the diabetic rats, LC decreases serum glucose level, improves the diameter and thickness of the epithelium of spermatogenic cells, reduces germ cells' apoptosis, and improves epididymal sperm parameters. Therefore, it seems that LC plays an effective role in diabetes-induced infertility.

Age-dependent changes in metabolic profile of turkey spermatozoa as assessed by NMR analysis

Metabolic profile of fresh turkey spermatozoa at three different reproductive period ages, namely 32, 44 and 56 weeks, was monitored by Nuclear Magnetic Resonance (NMR) spectroscopy and correlated to sperm quality parameters. The age-related decrease in sperm quality as indicated by reduction of sperm concentration, sperm mobility and osmotic tolerance was associated to variation in the level of specific water-soluble and liposoluble metabolites. In particular, the highest levels of isoleucine, phenylalanine, leucine, tyrosine and valine were found at 32 weeks of age, whereas aspartate, lactate, creatine, carnitine, acetylcarnitine levels increased during the ageing. Lipid composition also changed during the ageing: diunsaturated fatty acids level increased from 32 to 56 weeks of age, whereas a reduction of polyunsaturated fatty acids content was observed at 56 weeks. The untargeted approach attempts to give a wider picture of metabolic changes occurring in ageing suggesting that the reduction of sperm quality could be due to a progressive deficiency in mitochondrial energy producing systems, as also prompted by the negative correlation found between sperm mobility and the increase in certain mitochondrial metabolites.

Systematic review of antioxidant types and doses in male infertility: Benefits on semen parameters, advanced sperm function, assisted reproduction and live-birth rate

Objective

To explore the current evidence concerning the effect of oral antioxidant supplementation on various male fertility outcomes, as antioxidants are widely available compounds that are commonly used for the treatment of male infertility.

Materials and methods

PubMed, Medline and Cochrane electronic databases were searched according to a modified Preferred Reporting Items for Systemic Reviews and Meta-Analyses (PRISMA) guidelines looking for studies investigating the effect of antioxidant therapy on infertile men. The studies were explored looking for antioxidants: (i) types and doses; (ii) mechanism of action and rationale for use; and (iii) effect on the different outcome measures reported.

Results

In all, 26 studies reported a significant positive effect of antioxidant therapy on basic semen parameters, advanced sperm function, outcomes of assisted reproductive therapy, and live-birth rate. Vitamin E, vitamin C, carnitines, N-acetyl cysteine, co-enzyme Q10, zinc, selenium, folic acid and lycopene were most commonly used. The vitamins’ mechanism of action and reported doses is presented in Table 1, Table 2.

Conclusion

Antioxidants generally have a favourable effect on male fertility. Further studies are needed to identify the optimal antioxidant regimen that can be used safely and efficiently in clinical practice.

Ameliorative effects of l-carnitine on rats raised on a diet supplemented with lead acetate

Lead intoxication has been a major health hazard in humans. It affects people at all ages. Its toxicity is associated with various organs of the body and affects different metabolic pathways. Based on histological data, l-carnitine reduced the severity of tissue damage produced as a result of exposure of rats to lead acetate. The main objective of this study was to evaluate the underlying mechanism of protection offered by l-carnitine against lead acetate intoxication using male Sprague-Dawley rats. Forty male Sprague-Dawley rats were randomly divided into four groups with ten rats in each. The first group (G1) served as the control group and animals received standard diet only. The second group (G2) received lead acetate in their diet. The third group (G3) was the l-carnitine treated group and received the normal standard diet supplemented with l-carnitine. While the fourth group (G4) had a diet supplemented with both lead acetate and l-carnitine. At the end of each experiment, blood (serum and whole blood) were collected from each animal and analyzed for the following parameters: serum testosterone levels, serum nitric oxide and serum malondialdehyde. This is in addition to looking at the enzymatic activities of two important enzymes (superoxide dismutase and catalase) and on (glutathione reductase) which are indicative of the antioxidant activities in the whole blood. The results indicated that l-carnitine will counteract the undesirable effects of lead intoxication. It exerted its antioxidant potential by reducing the production of ROS and scavenging free radicals by maintaining and protecting the level of the of antioxidant enzymes SOD, CAT and glutathione peroxidase. Conclusion:l-Carnitine may play an important role in reversing the undesirable effects of lead intoxication. Future studies should be conducted to see whether such an effect is applicable in humans exposed to lead poising.