Selenium supplementation in the form of selenium nanoparticles and selenite sodium improves mature male mice reproductive performances

Selenium-Enriched Aspergillus oryzae A02 Enhances Testicular Antioxidant Capacity in Mice by Regulating Intestinal Microbiota and Serum Metabolite

Selenium (Se) is a trace element that is essential for health. Organic Se created by Se-enriched microorganisms has the characteristics of low toxicity, high bioavailability, and regulation of physiological functions. Here, the regulatory effect of Se-enriched Aspergillus oryzae A02 on the reproductive function of male mice and its potential molecular mechanism was studied. Specifically, twenty-four male mice were randomly divided into a control group and a Se-enriched A. oryzae A02 (Nano-Se) (daily gavage of 0.5 mg/kg, dissolved in saline) for an 8-week experiment. The results showed that Nano-Se intervention did not affect body weight and testicular index, but increased sperm concentration and seminiferous epithelium height in experimental mice, indicating that Nano-Se has the potential to improve the reproductive performance of male mice. Mechanistically, Nano-Se intervention increased the levels of antioxidant-related indicators catalase (CAT) and glutathione peroxidase (GSH-Px) in mouse serum, and increased the relative mRNA expression of GSH-Px, heme oxygenase-1 (HO-1), and NADPH quinine oxidoreductase-1 (NQO-1) in testicular tissues. We identified 9,10,13-trihydroxyoctadecenoic acids (TriHOMEs), stearidonic acid and selenomethionine linked with alpha-linolenic acid metabolism, selenocompound metabolism, folate biosynthesis, ubiquinone, and other terpenoid-quinone biosynthesis and biosynthesis of cofactors. In addition, Nano-Se did not influence the fecal bacterial alpha and beta diversity (P > 0.05), but increased the abundance of the Actinobacteriota and Proteobacteria phyla and the Staphylococcus and Corynebacterium genera, and lowered the abundance of the Bacteroidota phylum and the Lactobacillus and norank_f_Muribaculaceae genera. Nano-Se is considered a novel and promising nutritional regulator to improve reproductive function.

Selenium Improves Arsenic-Induced Male Reproductive Dysfunction by Regulating H3K14ac Level

Arsenic exposure has been known to be associated with male reproduction injury. Exploring the antidote of arsenic and ascertaining proper dose of antidote are important for detoxifying the male reproductive toxicity of arsenic. Selenium, which is essential for the male reproduction and spermatogenesis, can alleviate the toxicity of many environmental toxins, such as metals, and fluoride (F). Selenium relieves arsenic-induced reductions in spermatogenesis index and testicular function marker enzymes via promoting the antioxidative ability of rats. Our previous study has found that arsenic can induce male reproductive toxicity by affecting the level of H3K14ac in the testis, so we further investigate whether selenium can antagonize arsenic-induced male reproductive toxicity through the H3K14ac pathway and ascertain the appropriate dose of selenium. The results show that selenium intervention reduces the accumulation of arsenic in rat testis probably attributing to promote the excretion of arsenic from rat, then improves the testis injury induced by arsenic. Selenium intervention enhances sperm quality, testosterone level, and expression of steroidogenic genes by regulating H3K14ac level and expression of its associated enzymes (KAT2A, BAZ2A, and HDAC6), and thus alleviates the male reproductive toxicity of arsenic, and the proper dose of Se for mitigating arsenic male reproductive toxicity is 1 mg/kg.

A comprehensive review on potential role of selenium, selenoproteins and selenium nanoparticles in male fertility

Selenium (Se), a component of selenoproteins and selenocompounds in the human body, is crucial for the development of male reproductive organs, DNA synthesis, thyroid hormone, metabolism, and defence against infections and oxidative damage. In the testis, it must exceed a desirable level since either a shortage or an overabundance causes aberrant growth. The antioxidant properties of selenium are essential for preserving human reproductive health. Selenoproteins, which have important structural and enzymatic properties, control the biological activities of Se primarily. These proteins specifically have a role in metabolism and a variety of cellular processes, such as the control of selenium transport, thyroid hormone metabolism, immunity, and redox balance. Selenium nanoparticles (SeNPs) are less hazardous than selenium-based inorganic and organic materials. Upon being functionalized with active targeting ligands, they are both biocompatible and capable of efficiently delivering combinations of payloads to particular cells. In this review, we discuss briefly the chemistry, structure and functions of selenium and milestones of selenium and selenoproteins. Next we discuss the various factors influences male infertility, biological functions of selenium and selenoproteins, and role of selenium and selenoproteins in spermatogenesis and male fertility. Furthermore, we discuss the molecular mechanism of selenium transport and protective effects of selenium on oxidative stress, apoptosis and inflammation. We also highlight critical contribution of selenium nanoparticles on male fertility and spermatogenesis. Finally ends with conclusion and future perspectives.

In Vitro and In Vivo Studies on the Efficacy of Zinc-Oxide and Selenium Nanoparticle in Cryopreserved Goat (Capra hircus) Spermatozoa

Different nanoparticles (NPs) are currently being investigated for their potential role as cryoprotectant during semen cryopreservation in several mammalian species. It may be possible to improve semen quality following cryopreservation by supplementation of NPs in the freezing extenders. The present study was carried out in semen collected from four (4) Assam Hill Goat bucks (10 ejaculates per buck) to investigate the effect of supplementing zinc oxide (ZnO) and selenium (Se) NPs in Tris-citric acid-fructose yolk (TCFY) extender on in vitro sperm quality and in vivo fertility rate after freeze-thawing. The size morphology and zeta potential of ZnO and Se NPs were evaluated prior to its incorporation in the freezing extender. Qualified semen samples (> 70% progressive motility) were divided into five (5) aliquots and then diluted in TCFY extender containing ZnO and Se NP supplementation at different concentrations (T0, control; T1, 0.1 mg/mL ZnO NPs; T2, 0.5 mg/mL ZnO NPs; T3, 0.5 µg/mL Se NPs; and T4, 1 µg/mL Se NPs). Diluted semen was packed in 0.25 mL straws and then stored in liquid nitrogen. After thawing, post-thaw in vitro sperm attributes were evaluated. Finally, the effect of NPs on in vivo fertility rate was checked in heat-synched does (n = 70) by artificial insemination (AI) using straws that showed superior results during the in vitro study. Results showed that ZnO and Se NPs were poly-crystalline in nature with particle size below 100 nm (nm). The evaluated post-thaw sperm in vitro attributes were significantly (p < 0.001) higher in T1 in comparison to T0. The antioxidant enzyme activities were significantly (p < 0.001) higher in T1. Lipid peroxidation (LPO) profile was significantly (p < 0.001) lower in T1. Sperm motility and mitochondrial membrane potential (MMP) had a highly significant (r = 0.580, p < 0.05) association in T1. No significant (p > 0.05) differences in pregnancy rates were recorded after AI in the different treatments. In conclusion, extender supplemented with 0.1 mg/mL ZnO NPs improved post-thaw semen quality of goat spermatozoa consequently by increasing activities of endogenous antioxidant enzymes thereby lowering LPO levels. However, improved in vitro outcomes might not correspond to improved field fertility outcomes.

Bisphenol-S Influence on Oxidative Stress and Endocrine Biomarkers of Reproductive System: A Systematic Review and Meta-Analysis

Background

Bisphenol-S (BPS), as a new human public health concern, was introduced to the plastic industry by BPA-free labeled products following the restrictions of Bisphenol-A (BPA) as a safe alternative. However, recent research has revealed a controversial issue. In this regard, the present study aimed to review the relationship between BPS exposure and reproductive system dis/malfunction.

Methods

PubMed and other databases were searched up to January 2021. The standard mean difference (SMD) with a 95% confidence interval (CI) was calculated for the main parameters using the random-effects model. Finally, 12 studies with 420 subjects were included in this research. Forest plot, meta-regression, and non-linear dose-response effect were calculated for each parameter by random-effects model.

Results

Based on the results of in vitro assessment, a significant increase was found in the oxidative stress parameters, including superoxide dismutase (SMD: 0.63, 95% CI: 0.321, 0.939), thiobarbituric acid reactive substances (SMD: 0.760, 95% CI: 0.423, 1.096), and reactive oxygen species (SMD: 0.484, 95% CI: 0.132, 0.835). In addition, the hormonal assessment revealed a significant decrease in male testosterone concertation (SMD: -0.476, 95% CI: -0.881, -0.071). Moreover, in vivo examination revealed a significant decrease in hormonal parameters, such as female testosterone (SMD: -0.808, 95% CI: -1.149, -0.467), female estrogen (SMD: -2.608, 95% CI: -4.588, -0.628), female luteinizing hormone (SMD: -0.386, 95% CI: -0.682, -0.089), and female follicle-stimulating hormone (FSH) (SMD: -0.418, 95% CI: -0.716, -0.119). Besides, linear and non-linear correlations were detected in the main parameters.

Conclusion

In conclusion, based on the current meta-analysis, BPS was suggested to be toxic for the reproductive system, similar to the other bisphenols. Moreover, a possible correlation was indicated between oxidative and hormonal status disruption induced by BPS in male and female reproductive systems dis/malfunction.

Comprehensive review on the positive and negative effects of various important regulators on male spermatogenesis and fertility

With the increasing global incidence of infertility, the influence of environmental factors, lifestyle habits, and nutrients on reproductive health has gradually attracted the attention of researchers. The quantity and quality of sperm play vital roles in male fertility, and both characteristics can be affected by external and internal factors. In this review, the potential role of genetic, environmental, and endocrine factors; nutrients and trace elements in male reproductive health, spermatozoa function, and fertility potency and the underlying mechanisms are considered to provide a theoretical basis for clinical treatment of infertility.

Testicular Effect of Selenium Nanoparticles on Monosodium Glutamate Induced Alteration in Male Albino Rats

<b>Background and Objective:</b> The flavor enhancer Monosodium Glutamate (MSG) is mostly utilized in Asian and West African cuisines, especially in West African and Asian dishes. However, due to its availability, largely without labeling, in many food products, unintentional overuse of this food additive may occur. The objective of this study was to find out how selenium nanoparticles affected the toxicity of MSG in male albino rats' testicles. <b>Materials and Methods:</b> As 35 Wistar male rats partitioned into 5 groups: G1: Control rats, G2: Received Se-NPs at 0.4 mg kg¹ b.wt., orally, G3: Injected with MSG at a daily dose of 4 g kg¹ b.wt., intraperitoneally (IP), G4: Ingested a daily oral dose of Se-NPs for 7 successive days and on the 7th day, received the first dose of MSG IP 4 g kg¹ b.wt., then received both treatments till the end of the study and G5: Administered a daily oral dose of 4 g kg¹ MSG, followed by Se-NPs at a daily dose of 0.4 mg kg¹ b.wt., the experiment continued for 28 days. Serum testosterone hormone, Follicle Stimulating Hormone (FSH), Luteinizing Hormone (LH), the levels of serum lipid peroxidation (MDA), reduced Glutathione (GSH), Glutathione Peroxidase (GSH-Px), superoxide dismutase (SOD) and Lactate Dehydrogenase (LDH) were estimated and samples from testis were separated for histological analysis. <b>Results:</b> The MSG treatment induced a significant decline in the values of serum testosterone, FSH, LH, GSH, GSH-Px and SOD. It also increased the values of serum MDA and LDH and spermatic arrest. While, the administration of Se-NPs orally before MSG treatment resulted in a decline in the values of serum MDA and LDH, an elevation in the values of serum GSH, GSH-PX and SOD, testosterone, FSH, LH and reappearance of sperm. <b>Conclusion:</b> The use of Se-NPs as a protector exhibited more improvement in values of estimated hormones and oxidative stress markers than using it as a therapy.

Long-term intake of aspartame-induced cardiovascular toxicity is reflected in altered histochemical parameters, evokes oxidative stress, and trigger P53-dependent apoptosis in a mouse model

Aspartame (ASP) is probably the best known artificial sugar substitute that is used widely in food. Many experimental studies have reported the toxicity of long-term administration of ASP in various organ tissues. However, there is little evidence available about the nature and mechanisms of the adverse effects of long-term consumption of ASP on the cardiovascular system. This study was conducted to evaluate the possible effects of ASP on heart tissue. For this study 36 mature male mice were divided into one control group and three groups which received respectively 40 mg/kg, 80 mg/kg and 160 mg/kg ASP orally, for 90 days. ASP at the doses of 80 and 160 mg/kg increased the serum content of malondialdehyde (MDA), but decreased serum nitric oxide (NO), creatine kinase (CK) and CK-MB, as well as blood superoxide dismutase (SOD) levels. Serum level of total anti-oxidant capacity (TAC) in blood was also reduced in serum at the dose of 80 mg/kg. Histochemical staining, including Periodic acid-Schiff, Masson's trichrome and Verhoeff-van Gieson staining, indicated that ASP at doses of 80 and 160 mg/kg reduced glycogen deposition and decreased the number of collagen and elastic fibres in the cardiac tissue. The cardiac expression of pro-apoptotic genes, including P53, Bax, Bcl-2 and Caspase-3, was modulated at the dose of 160 mg/kg. Moreover, transcription of Caspase-3 was up-regulated at the dose of 80 mg/kg. In conclusion, long-term consumption of ASP any higher than the acceptable daily intake (40 mg/kg) appears to act by promoting oxidative stress, has the potential to alter both histopathological and biochemical parameters, and induces P53-dependent apoptosis in cardiac tissue.

The Effect of Selenium Nanoparticles versus Royal Jelly against Cisplatin-Induced Testicular Toxicity in Adult Male Albino Rats: A Light and Transmission Electron Microscopic Study

Background and Aim

Cisplatin (Cis) is a highly effective chemotherapeutic agent. However, it produces severe testicular toxicity. It was reported that some antioxidants could overcome this toxicity. Selenium nanoparticles and royal jelly (RJ) were among these reported antioxidants. Therefore, this study was designed to compare these two antioxidants in protecting the testes against Cis-induced toxicity.

Materials and Methods

This study was conducted on sixty healthy adult male albino rats (weight: 200-220 g) randomized into six groups, ten animals each. Group I (control), Group II (animals received intragastric Nano Selenium), Group III (animals received intragastric RJ), Group IV (animals received an IP injection of Cis 7 mg/kg), Group V (animals received intragastric Nano Selenium, and Cis injection), and Group VI (animals received intragastric RJ and Cis injection). After 10 days, the animals were sacrificed by cervical decapitation. The testes were weighted, and specimens from the left testis were processed for histological and immunohistochemical techniques, whereas specimens from the right testes were prepared for transmission electron microscopic examination.

Results

Cis-treated animals had significantly reduced weight of their testes. Light microscopic examination revealed severe histopathological changes in the germinal epithelium and Leydig cells, confirmed with electron microscopic examination. There was a significant increase in the color area percentage of Caspase-3 immunostaining of the germinal epithelium and Leydig cells, compared to that of the control group. Group II and III were similar to control group. Both Groups V and VI revealed significant preservation compared to the Cis group.

Conclusion

Selenium nanoparticles and RJ partially improved testis from Cis-induced toxicity, However, there was no significant difference between both groups.

Comparison of Selenium Nanoparticles and Sodium Selenite on the Alleviation of Early Atherosclerosis by Inhibiting Endothelial Dysfunction and Inflammation in Apolipoprotein E-Deficient Mice

Atherosclerosis and related cardiovascular diseases represent the greatest threats to human health, worldwide. Previous animal studies showed that selenium nanoparticles (SeNPs) and Na₂SeO₃ might have anti-atherosclerotic activity, but the underlying mechanisms are poorly elucidated. This study compared the anti-atherosclerotic activity of SeNPs stabilized with chitosan (CS-SeNPs) and Na₂SeO₃ and the related mechanism in a high-fat-diet-fed apolipoprotein E-deficient mouse model of atherosclerosis. The results showed that oral administration of both CS-SeNPs and Na₂SeO₃ (40 μg Se/kg/day) for 10 weeks significantly reduced atherosclerotic lesions in mouse aortae. Mechanistically, CS-SeNPs and Na₂SeO₃ not only alleviated vascular endothelial dysfunction, as evidenced by the increase of serum nitric oxide level and the decrease of aortic adhesion molecule expression, but also vascular inflammation, as evidenced by the decrease of macrophage recruitment as well as the expression of proinflammatory molecules. Importantly, these results were replicated within in-vivo experiments on the cultured human endothelial cell line EA.hy926. Overall, CS-SeNPs had a comparable effect with Na₂SeO₃ but might have more potential in atherosclerosis prevention due to its lower toxicity. Together, these results provide more insights into the mechanisms of selenium against atherosclerosis and further highlight the potential of selenium supplementation as a therapeutic strategy for atherosclerosis.

Role for Selenium in Metabolic Homeostasis and Human Reproduction

Selenium (Se) is a micronutrient essential for life. Dietary intake of Se within the physiological range is critical for human health and reproductive functions. Selenium levels outside the recommended range have been implicated in infertility and variety of other human diseases. However, presently it is not clear how different dietary Se sources are processed in our bodies, and in which form or how much dietary Se is optimum to maintain metabolic homeostasis and boost reproductive health. This uncertainty leads to imprecision in published dietary guidelines and advice for human daily intake of Se and in some cases generating controversies and even adverse outcomes including mortality. The chief aim for this review is to describe the sources of organic and inorganic Se, the metabolic pathways of selenoproteins synthesis, and the critical role of selenprotenis in the thyroid gland homeostasis and reproductive/fertility functions. Controversies on the use of Se in clinical practice and future directions to address these challenges are also described and discussed herein.

Production and Use of Selenium Nanoparticles as Fertilizers

The synergy problem was discussed linking Se nanoparticles and different soil fertility agents. Se zero-valent-state nanoparticles were investigated as fertilizers and antioxidants. A technology was proposed for producing Se zero-valent-state nanoparticles. Se nanoparticles were obtained by laser ablation of Se in water using a fiber ytterbium laser, with a wavelength between 1060 and 1070 nm, a pulse repetition rate of 20 kHz, a pulse duration of 80 ns, and an average power of 20 W, and a copper vapor laser with wavelengths of 510.6 and 578.2 nm and an average power of 8 W. The main particle mass part shifted from 800 nm to a size less than 100 nm, corresponding to the increase in the laser fragmentation time. The resulting nanoparticles were monodisperse in size and mass. The Se nanoparticle water suspension was introduced into the soil. The soil Se nanoparticle concentrations were about 1, 5, 10, and 25 μg kg-1. An experiment was carried out in a climate chamber in two series: (1) growing plants in soil imitating the standard organogenesis environment conditions such as illumination of 16 h per day, temperature of 22 °C, soil humidity of 25% SDW, and an experiment duration of 30 days and (2) growing plants in soil under changing environmental conditions of organogenesis. The standard environmental conditions for the first 10 days are illumination of 16 h day-1, temperature of 22 °C, and soil humidity of 25% SDW. The plant stress for 5 days is hyperthermia of 40 °C. The standard environmental conditions for the next 15 days are illumination of 16 h day-1, temperature of 22 °C, and soil humidity of 25% SDW. At standard organogenesis, the plant leaf plate surface area was 30 ± 2 cm2 in the control option, and the Se nanoparticle doses were correspondingly 1 μg kg-1 for 32 ± 3 cm2, 5 μg kg-1 for 37 ± 2 cm2, 10 μg kg-1 for 38 ± 3 cm2, and 25 μg kg-1 for 28 ± 4 cm2. Hyperthermia stressed plant growth was studied. The highest plant growth rate was in Se nanoparticle concentrations of 5 and 10 μg kg-1. The eggplant growth on the soil with the Se nanoparticle addition at a concentration of 10 μg kg-1 of leaf plate surface area was twice compared to the eggplant growth in untreated soil. The same was for tomato plants. The leaf plate surface area of the cucumber plant grown using Se nanoparticles was 50% higher compared to the control option. The Biogeosystem technique methodology of 20-45 cm soil-layer intrasoil milling for soil multilevel aggregate system formation and intrasoil pulse continuous-discrete watering for soil water regime control was proposed for the Se nanoparticles for better function in the real soil, providing a synergy effect of soil mechanical processing, nanoparticles, humic substances, and polymicrobial biofilms on soil fertility.

Long-Term Effect of Aspartame on Male Reproductive System: Evidence for Testicular Histomorphometrics, Hsp70-2 Protein Expression and Biochemical Status

Background

Aspartame is one of the most commonly consumed artificial sweeteners that is widely used in foodstuffs. There are many debatable reports about aspartame toxicity in different tissues; however, on the subject of its effects on the reproductive system, few literatures are available. The present study was carried out for evaluating effects of aspartame on the reproductive system in male mice.

Materials and Methods

In this experimental study, a total of 36 adult male mice were randomly divided into four groups of nine animals each. Three groups received aspartame at doses of 40, 80 and 160 mg/kg (gavage) for 90 days; also, a control group was considered. Twenty-four hours after the last treatment, animals were sacrificed. Then, body and testis weights, sperm parameters, serum testosterone concentration, total antioxidant capacity, and malondialdehyde (MDA) levels, antioxidant enzymes [superoxide dismutase (SOD), catalase (CAT) and glutathione peroxidase (GSH-Px)] activities in blood, histomorphometrical indices and histochemical changes in testis were evaluated; also, mRNA and immunohistochemical expression of Hsp70-2 was measured in testis tissue.

Results

The results revealed remarkable differences in sperm parameters, testosterone and oxidative stress biomarkers levels, and histomorphometrical indices, between the control and treatment groups. Also, in 80 and 160 mg/kg aspartametreated groups, expression of Hsp70-2 was decreased. Besides, in the aspartame receiving groups, some histochemical changes in testicular tissue were observed.

Conclusion

The findings of the present study elucidated that long-term consumption of aspartame resulted in reproductive damages in male mice through induction of oxidative stress.

Comparison between the Effects of Adding Vitamins, Trace Elements, and Nanoparticles to SHOTOR Extender on the Cryopreservation of Dromedary Camel Epididymal Spermatozoa

Simple Summary

This is a comprehensive study to compare between the effects of different supplements (vitamins C and E, trace elements Na₂SeO₃ and ZnSO₄, and nanoparticles of zinc oxide and selenium) to the semen extender of camel epididymal spermatozoa during cooling and freezing/thawing cryopreservation. Supplementation of the semen SHOTOR extender with zinc oxide and selenium nanoparticles lead to improved progressive motility, vitality, and anti-oxidative defense, and reduced the ultrastructural abnormalities in camel epididymal spermatozoa.

Abstract

There are several obstacles in camel semen cryopreservation; such as increasing semen viscosity and the reduction in motile spermatozoa after ejaculation. Epididymal spermatozoa offer an efficient alternative to overcome these problems and are well-suited for artificial insemination in camels. In the current study, we compared the effects of supplementation with vitamin C, E, inorganic trace elements of selenium (Na₂SeO₃) and zinc (ZnSO₄), and zinc and selenium nanoparticles (ZnONPs and SeNPs, respectively) on the cryopreservation of dromedary camel epididymal spermatozoa. When the SHOTOR extender was supplemented with ZnONPs and SeNPs; the sperm showed increased progressive motility; vitality; and membrane integrity after cooling at 5 °C for 2 h; when compared to the control and vitamin-supplemented groups. Moreover, the ZnONPs and SeNPs supplementation improved the progressive motility, vitality, sperm membrane integrity, ultrastructural morphology, and decreased apoptosis when frozen and thawed. SeNPs significantly increased reduced glutathione (GSH), superoxide dismutase (SOD), and decreased lipid peroxide malondialdehyde (MDA) levels. The advantageous effects of the trace elements were potentiated by reduction into a nano-sized particle, which could increase bioavailability and reduce the undesired liberation of toxic concentrations. We recommend the inclusion of SeNPs or ZnONPs to SHOTOR extenders to improve the cryotolerance of camel epididymal spermatozoa.

Role of Selenium and Selenoproteins in Male Reproductive Function: A Review of Past and Present Evidences

Selenium (Se) is an important trace mineral having many essential roles at the cellular and organismal levels in animal and human health. The biological effects of Se are mainly carried out by selenoproteins (encoded by 25 genes in humans and 24 in mice). As an essential component of selenoproteins, Se performs structural and enzymic roles; in the latter context it is well known for its catalytic and antioxidative functions. Studies involving different animal models have added great value to our understanding regarding the potential implications of Se and selenoproteins in mammalian fertility and reproduction. In this review, we highlight the implications of selenoproteins in male fertility and reproduction followed by the characteristic biological functions of Se and selenoproteins associated with overall male reproductive function. It is evident from observations of past studies (both animal and human) that Se is essentially required for spermatogenesis and male fertility, presumably because of its vital role in modulation of antioxidant defense mechanisms and other essential biological pathways and redox sensitive transcription factors. However, bearing in mind the evidences from mainstream literature, it is also advisable to perform more studies focusing on the elucidation of additional roles played by the peculiar and canonical selenoproteins i.e., glutathione peroxidase 4 (GPX4) and selenoprotein P (SELENOP) in the male reproductive functions. Nevertheless, search for the elucidation of additional putative mechanisms potentially modulated by other biologically relevant selenoproteins should also be included in the scope of future studies. However, as for the implication of Se in fertility and reproduction in men, though a few clinical trials explore the effects of Se supplementation on male fertility, due to inconsistencies in the recruitment of subjects and heterogeneity of designs, the comparison of such studies is still complicated and less clear. Therefore, further research focused on the roles of Se and selenoproteins is awaited for validating the evidences at hand and outlining any therapeutic schemes intended for improving male fertility. As such, new dimensions could be added to the subject of male fertility and Se supplementation.