Cytotoxic and genotoxic effects of titanium dioxide nanoparticles in testicular cells of male wistar rat

The effect of TiO2 nanoparticles on antral follicles is dependent on the nanoparticle internalization rate

Titanium dioxide nanoparticles (TiO2 NPs) are among the most widely produced metallic NPs due to commercial and industrial applications in products including food, cosmetics, paints, and plastics. TiO2 NPs are released into the environment posing health risks for humans and wildlife. Widespread uses have raised concerns about the potential toxicity of TiO2 NPs in reproduction. The ovary is an important endocrine organ responsible for sex steroid hormone production and folliculogenesis. NPs can reach the ovary, but limited information is available regarding NP toxicity and its effects on ovarian antral follicles. Thus, we tested the hypothesis that exposure to TiO2 NP affects sex hormone synthesis, oxidative stress, and antioxidant response in ovarian antral follicles in vitro. In addition, we characterized the NP internalization in the antral follicles over time to determine any association between NP internalization and effects on the antral follicle. Antral follicles were exposed to vehicle control or TiO2 NPs (5, 25, and 50 µg/ml) for 96 h. The lowest NP concentration (5 µg/ml) showed no internalization and no effects in antral follicles. The 25-µg/ml concentration had the highest internalization rate, leading to increased mRNA ratio of Bax to Bcl2. Interestingly, the highest concentration (50 µg/ml) showed lower internalization compared with the 25 µg/ml, with altered levels of steroidogenic involved genes and increased levels of progesterone and testosterone compared with control. In conclusion, these data suggest that TiO2 NP is internalized in antral follicles as the first step process in impairing follicle functions.

Bio distribution and acute toxicity profiling of Pluronic F127 coated Titanium dioxide nanotubes in adult Wistar rats

Metal and metal oxide nanoparticles are gaining immense attention among researchers owing to their admirable application potentials in various therapeutic events. Titanium dioxide (TiO2) has been recognized as one of the leading candidates in this category and holds wide interest within the scientific community. Among the various morphological nanoforms of TiO2, nanotube is grabbing remarkable attention as they have succeeded as an active vehicle in various medical procedures like intravascular stenting, drug delivery, as biosensors etc. This ultimately demands toxicity profiling of nanotubes in various aspects. Present study elaborates a concept through which acute toxicity profiling of TiO2 nanotubes in adult Wistar rats is presented. TNTs were synthesized via solvo-thermal approach and surface coated with a biocompatible polymer; Pluronic-F127 (P-F127). This step assists in ameliorating the troubles associated with the nanomaterial dispersion stability. The experimental rats were intraperitoneally administered with TNT-P (10 mg/kg) and sacrificed on different time periods (3rd, 7th and 14th days). Biodistribution of the material was tracked in major tissues including brain, liver, spleen and kidneys. A set of acute toxicity studies was performed which comprises hematology evaluation, biochemical studies, antioxidant detection, analysis of urine parameters, immune modulation study and histopathology evaluation. Many of the experiments revealed an unaltered physiological response in rats; except for some biochemical and hematology parameters. Overall study suggests that, TNT-P do not result into a negative response in Wistar rats over 14 days.

Characterization of Food-Additive Titanium Dioxide and Dietary Exposure to Titanium Dioxide Nanoparticles among the Chinese Population

Titanium dioxide (TiO2) is a prevalent food additive, yet comprehensive data on particle size and dietary exposure are lacking in China. Transmission electron microscopy results revealed that the quantitative proportion of nanoparticles (NPs) in food-additive TiO2 was 37.7%, with a mass fraction of 9.89%. Laboratory test results showed that among the domestic products surveyed, candies excluding gum-based candies contained the highest content of TiO2. Using consumption data from the China Health and Nutrition Survey in 2018, the average dietary exposure for TiO2 and TiO2 NPs in the Chinese population were calculated at 34.84 and 3.44 μg/kg bw/day, respectively. The primary dietary sources were puffed food and powdered drinks. Exposure varied significantly across age and region, with children and Inner Mongolia residents having the highest intake. TiO2 NP exposure showed a negative correlation with age. Despite this, the dietary exposure risk of TiO2 NPs for the Chinese population remains deemed acceptable.

The toxicity of superparamagnetic iron oxide nanoparticles induced on the testicular cells: In vitro study

Superparamagnetic iron oxide nanoparticles (SPIONs) have gained significant attention in biomedical research due to their potential applications. However, little is known about their impact and toxicity on testicular cells. To address this issue, we conducted an in vitro study using primary mouse testicular cells, testis fragments, and sperm to investigate the cytotoxic effects of sodium citrate-coated SPIONs (Cit_SPIONs). Herein, we synthesized and physiochemically characterized the Cit_SPIONs and observed that the sodium citrate diminished the size and improved the stability of nanoparticles in solution during the experimental time. The sodium citrate (measured by thermogravimetry) was biocompatible with testicular cells at the used concentration (3%). Despite these favorable physicochemical properties, the in vitro experiments demonstrated the cytotoxicity of Cit_SPIONs, particularly towards testicular somatic cells and sperm cells. Transmission electron microscopy analysis confirmed that Leydig cells preferentially internalized Cit_SPIONs in the organotypic culture system, which resulted in alterations in their cytoplasmic size. Additionally, we found that Cit_SPIONs exposure had detrimental effects on various parameters of sperm cells, including motility, viability, DNA integrity, mitochondrial activity, lipid peroxidation (LPO), and ROS production. Our findings suggest that testicular somatic cells and sperm cells are highly sensitive and vulnerable to Cit_SPIONs and induced oxidative stress. This study emphasizes the potential toxicity of SPIONs, indicating significant threats to the male reproductive system. Our findings highlight the need for detailed development of iron oxide nanoparticles to enhance reproductive nanosafety.

Overview of in vitro-in vivo extrapolation approaches for the risk assessment of nanomaterial toxicity

Nanomaterials are increasingly used in many applications due to their enhanced properties. To ensure their safety for humans and the environment, nanomaterials need to be evaluated for their potential risk. The risk assessment analysis on the nanomaterials based on animal or in vivo studies is accompanied by several concerns, including animal welfare, time and cost needed for the studies. Therefore, incorporating in vitro studies in the risk assessment process is increasingly considered. To be able to analyze the potential risk of nanomaterial to human health, there are factors to take into account. Utilizing in vitro data in the risk assessment analysis requires methods that can be used to translate in vitro data to predict in vivo phenomena (in vitro-in vivo extrapolation (IVIVE) methods) to be incorporated, to obtain a more accurate result. Apart from the experiments and species conversion (for example, translation between the cell culture, animal and human), the challenge also includes the unique properties of nanomaterials that might cause them to behave differently compared to the same materials in a bulk form. This overview presents the IVIVE techniques that are developed to extrapolate pharmacokinetics data or doses. A brief example of the IVIVE methods for chemicals is provided, followed by a more detailed summary of available IVIVE methods applied to nanomaterials. The IVIVE techniques discussed include the comparison between in vitro and in vivo studies, methods to rene the dose metric or the in vitro models, allometric approach, mechanistic modeling, Multiple-Path Particle Dosimetry (MPPD), methods using organ burden data and also approaches that are currently being developed.

Comparative effects of chemical and green zinc oxide nanoparticles in caprine testis: ultrastructural and steroidogenic enzyme analysis

Recent advancements in nanotechnology has opened up enormous possibilities in diverse sectors such as industries, agriculture, environmental remediation, electronics, medicine and varied industries. Among metal oxide nanoparticles zinc oxide nanoparticles has gained considerable attention due to their fascinating physiochemical properties. Rapid growth in the use of zinc oxide nanoparticles (ZnONPs) in daily household products, food and feed additives, biological products, medicine, as antimicrobial agents, electronics and agriculture, creates serious toxic potential risks of these engineered nanoparticles on living organisms. The aim of present study was to assess the effects of synthesized chemical ZnONPs and green ZnONPs on testicular tissue of Capra hircus (goat) in vitro. The reproductive stress was analyzed by ultrastructural damage, change in frequency of apoptotic cells and alteration in steroidogenic enzyme activity. The transmission electron micrographs of testicular cells after treatment with chemical and green ZnONPs at three doses (10 µg/ml, 20 µg/ml and 30 µg/ml) for exposure duration 4 h and 8 h illustrated that chemical nanoparticles induced more alterations, identified as ruptured nuclear membrane, condensation and margination of chromatin material in somatic cells and germ cells in the seminiferous tubules, presence of apoptotic bodies in nucleus of spermatocytes and spermatids, reduction in number of cell organelles, vacuolization and hyalinization of cytoplasm. Maximum damage was observed after treatment of testicular tissues with 30 µg/ml of chemical ZnONPs for 8 h exposure duration. However, the green ZnONPs were found to be less toxic as evidenced by few apoptotic characteristics in testicular cells. The results of fluorescence assay by acridine orange staining showed significant increase in the percentage of apoptotic cells in chemical treated groups as compared to green and control groups. Decreased enzyme activity of 3β-Hydroxysteroid dehydrogenase and 17β-Hydroxysteroid dehydrogenase was assayed in chemical ZnONPs than green ZnONPs treated groups. Our results confirm that chemical ZnONPs are significantly more toxic in comparison to green ZnONPs and adversely affects the male fertility.

The effects of titanium dioxide (TiO2) nanoparticles on physiological, biochemical, and antioxidant properties of Vitex plant (Vitex agnus - Castus L)

Titanium dioxide nanoparticles (TiO2NPs) are widely used in agriculture in order to increase the yield and growth characteristics of plants. This study investigated the effects of TiO2NPs on photosynthetic pigments and several biochemical activities and antioxidant enzymes of the Vitex plant. Different concentrations of nanoparticles (0, 200, 400, 600 and 800 ppm) at five levels were sprayed on Vitex plants on the 30th day of the experiment. TiO2NPs at different concentrations had positive effects on root and shoot dry weight and a negative effect on leaf dry weight. The amount of chlorophyll increased with the concentration of TiO2NPs; however, the amount of chlorophyll b showed a decreasing trend while the total chlorophyll had a constant trend. The highest amount of soluble sugar was obtained in the treatment of 200 ppm nanoparticles. The application of TiO2NPs did not have any effect on the content of proline and soluble proteins of Vitex plant. The effects of foliar TiO2NPs, compared to the control, showed a significant increase in the activity of antioxidant enzymes. In general, TiO2NPs had a favorable effect on dry matter production and some antioxidant and biochemical properties of the Vitex plant.

Toxic effects of titanium dioxide nanoparticles on reproduction in mammals

Titanium dioxide nanoparticles (nano-TiO₂) are widely used in food, textiles, coatings and personal care products; however, they cause environmental and health concerns. Nano-TiO₂ can accumulate in the reproductive organs of mammals in different ways, affect the development of the ovum and sperm, damage reproductive organs and harm the growth and development of offspring. The oxidative stress response in germ cells, irregular cell apoptosis, inflammation, genotoxicity and hormone synthesis disorder are the main mechanisms of nano-TiO₂ toxicity. Possible measures to reduce the harmful effects of nano-TiO₂ on humans and nontarget organisms have emerged as an underexplored topic requiring further investigation.

Nanoparticles Induced Oxidative Damage in Reproductive System and Role of Antioxidants on the Induced Toxicity

Nanotechnology is used in a variety of scientific, medical, and research domains. It is significant to mention that there are negative and severe repercussions of nanotechnology on both individuals and the environment. The toxic effect of nanoparticles exerted on living beings is termed as nanotoxicity. Nanoparticles are synthesized by various methods such as chemical, biological, physical, etc. These nanoparticles’ nanotoxicity has been observed to vary depending on the synthesis process, precursors, size of the particles, etc. Nanoparticles can enter the cell in different ways and can cause cytotoxic effects. In this review, the toxicity caused in the reproductive system and the role of the antioxidants against the nanotoxicity are briefly explained.

The combined effect of titanium dioxide nanoparticles and cypermethrin on male reproductive toxicity in rats

Titanium nanoparticles and pyrethroid pesticides are now being widely used in industrial, agriculture, and biomedical applications. In recent years, their health safety profiles have aroused concerns among health scientists. This study mainly explored the combined effects of titanium dioxide nanoparticles (TiO2NPs) and cypermethrin (CYP) on reproductive toxicity in male rats by gavage for 90 days. Thirty-two male Sprague-Dawley rats were assigned to four groups: the control group, the TiO2NPs group, the CYP group, and the combined titanium dioxide nanoparticles with cypermethrin (TiO2NPs + CYP) group. The results of biochemical analysis on testicular tissue homogenate showed that TiO2NPs and CYP mixtures decreased the activities of glutathione peroxidase (GSH-Px) and catalase (CAT) while increasing the activity of malondialdehyde (MDA) and lactate dehydrogenase (LDH). Meanwhile, the results of two-way factorial analysis of variance (ANOVA) showed a significant effect on GSH-Px, CAT, LDH, testicular cell apoptosis, and sperm quality in rats after exposure. Furthermore, the combined exposure group exhibited apoptosis of testicular cells and DNA damage. The results indicated that exposure to a mixture of TiO2NPs and CYP had adverse effects on the reproductive status of male rats.

Bioinspired engineered nickel nanoparticles with multifunctional attributes for reproductive toxicity

Nickel nanoparticles (Ni-NPs) have potential applications in high-tech sectors such as battery manufacturing, catalysis, nanotube printing and textile. Apart from their increasing utilisation in daily life, there are concerns about their hazardous nature as they are highly penetrable in biological systems. The carcinogenic and mutagenic ability of Ni-NPs is evident but the research gaps are still there concerning the safety evaluation of Ni-NPs regarding male reproductive ability. This controlled randomized research was planned to assess the male reproductive toxicity of Ni-NPs in Sprague Dawley rats. Ni-NPs of spherical shape and mean particle size of 56 nm were used in the study, characterized by SEM, EDS and XRD. The twenty-five healthy rats (200-220 g) were used for toxicity investigation of Ni-NPs and divided into five groups; negative control (0 Ni-NPs), placebo group (0.9% saline) and three Ni-NPs treated groups (@ 15, 30 and 45 mg/kg BW). The results of 14 days of intraperitoneal exposure to Ni-NPs revealed that a higher dose (45 mg/kg BW) of Ni-NPs caused a significant reduction in body weight, serum testosterone, daily sperm production while the testis index and Ni accumulation and histological changes (necrosis in basement membrane and seminiferous tubules, vacuole formation) in testicular tissues increased with increasing dose of Ni-NPs. It can be concluded from the study that Ni-NPs have potential reproductive toxicity. This study provided the baseline data of Ni-NPs toxicity for the male reproductive system and can be applied for risk assessment in Ni-NPs based products.

Impact of Nanoparticles on Male Fertility: What Do We Really Know? A Systematic Review

The real impact of nanoparticles on male fertility is evaluated after a careful analysis of the available literature. The first part reviews animal models to understand the testicular biodistribution and biopersistence of nanoparticles, while the second part evaluates their in vitro and in vivo biotoxicity. Our main findings suggest that nanoparticles are generally able to reach the testicle in small quantities where they persist for several months, regardless of the route of exposure. However, there is not enough evidence that they can cross the blood-testis barrier. Of note, the majority of nanoparticles have low direct toxicity to the testis, but there are indications that some might act as endocrine disruptors. Overall, the impact on spermatogenesis in adults is generally weak and reversible, but exceptions exist and merit increased attention. Finally, we comment on several methodological or analytical biases which have led some studies to exaggerate the reprotoxicity of nanoparticles. In the future, rigorous clinical studies in tandem with mechanistic studies are needed to elucidate the real risk posed by nanoparticles on male fertility.

Impact of chitosan administration on titanium dioxide nanoparticles induced testicular dysfunction

The potential reproductive toxic effects of oral TiO₂ NPs in adult male rats as well as the possible alleviation of chitosan administration was investigated. Animals were allocated to four groups; the first group received deionized water and was assigned as a control group. In the second group, rats received chitosan at a dose of 5 mg/kg BW/day. The third group was designed for administration of TiO₂ NPs at a dose of 150 mg/kg BW/day (1/80 LD₅₀). Rats in the fourth group received both TiO₂ NPs and chitosan. After 14 days, TiO₂ NPs induced testicular lipid peroxidation as well as oxidative stress. Nano-titanium significantly upregulated genes that encode apoptosis and inflammation in testicular tissue. Moreover, it induced histological alteration in the testicular structure with impairment in spermatogenesis via reduction of PCNA immune-staining. Chitosan administration significantly improved the activities of testicular GPx, SOD, and CAT enzymes. In addition, it significantly down-regulated the relative expressions of pro-apoptotic and pro-inflammatory testicular genes. Chitosan was able to improve the testicular architecture as well as spermatogenesis. The current study revealed the capability of chitosan to ameliorate nano-titanium induced testicular toxicity. Thus, attention should be given to the extensive consumption of nano-titanium particles.

Ingestion of titanium dioxide nanoparticles: a definite health risk for consumers and their progeny

Titanium dioxide (TiO₂) is one of the most commonly used nanomaterials in the world. Additive E171, which is used in the food industry, contains a nanometric particle fraction of TiO₂. Oral exposure of humans to these nanoparticles (NPs) is intensive, leading to the question of their impact on health. Daily oral intake by rats of amounts of E171 that are relevant to human intake has been associated with an increased risk of chronic intestinal inflammation and carcinogenesis. Due to their food preferences, children are very exposed to this NP. Furthermore, maternal-foetal transfer of TiO₂ NPs during pregnancy, as well as exposure of the offspring by breastfeeding, have been recently described. In France, the use of E171 in the production of foodstuffs was suspended in January 2020 as a precautionary measure. To provide some answers to this public health problem and help global regulatory agencies finalize their decisions, we reviewed in vitro and in vivo studies that address the effects of TiO₂ NPs through oral exposure, especially their effects on the gastrointestinal tract, one of the most exposed tissues. Our review also highlights the effects of exposure on the offspring during pregnancy and by breastfeeding.

Evaluation of Zebrafish DNA Integrity after Individual and Combined Exposure to TiO2 Nanoparticles and Lincomycin

Environmental contamination by nanoparticles (NPs) and drugs represents one of the most debated issues of the last years. The aquatic biome and, indirectly, human health are strongly influenced by the negative effects induced by the widespread presence of pharmaceutical products in wastewater, mainly due to the massive use of antibiotics and inefficient treatment of the waters. The present study aimed to evaluate the harmful consequences due to exposure to antibiotics and NPs, alone and in combination, in the aquatic environment. By exploiting some of their peculiar characteristics, such as small size and ability to bind different types of substances, NPs can carry drugs into the body, showing potential genotoxic effects. The research was conducted on zebrafish (Danio rerio) exposed in vivo to lincomycin (100 mg/L) and titanium dioxide nanoparticles (TiO₂ NPs) (10 µg/L) for 7 and 14 exposure days. The effects on zebrafish were evaluated in terms of cell viability, DNA fragmentation, and genomic template stability (GTS%) investigated using Trypan blue staining, TUNEL assay, and the random amplification of polymorphic DNA PCR (RAPD PCR) technique, respectively. Our results show that after TiO₂ NPs exposure, as well as after TiO₂ NPs and lincomycin co-exposure, the percentage of damaged DNA significantly increased and cell viability decreased. On the contrary, exposure to lincomycin alone caused only a GTS% reduction after 14 exposure days. Therefore, the results allow us to assert that genotoxic effect in target cells could be through a synergistic effect, also potentially mediated by the establishment of intermolecular interactions between lincomycin and TiO₂ NPs.

Switching to nanonutrients for sustaining agroecosystems and environment: the challenges and benefits in moving up from ionic to particle feeding

The worldwide agricultural enterprise is facing immense pressure to intensify to feed the world's increasing population while the resources are dwindling. Fertilizers which are deemed as indispensable inputs for food, fodder, and fuel production now also represent the dark side of the intensive food production system. With most crop production systems focused on increasing the quantity of produce, indiscriminate use of fertilizers has created havoc for the environment and damaged the fiber of the biogeosphere. Deteriorated nutritional quality of food and contribution to impaired ecosystem services are the major limiting factors in the further growth of the fertilizer sector. Nanotechnology in agriculture has come up as a better and seemingly sustainable solution to meet production targets as well as maintaining the environmental quality by use of less quantity of raw materials and active ingredients, increased nutrient use-efficiency by plants, and decreased environmental losses of nutrients. However, the use of nanofertilizers has so far been limited largely to controlled environments of laboratories, greenhouses, and institutional research experiments; production and availability on large scale are still lagging yet catching up fast. Despite perceivable advantages, the use of nanofertilizers is many times debated for adoption at a large scale. The scenario is gradually changing, worldwide, towards the use of nanofertilizers, especially macronutrients like nitrogen (e.g. market release of nano-urea to replace conventional urea in South Asia), to arrest environmental degradation and uphold vital ecosystem services which are in critical condition. This review offers a discussion on the purpose with which the nanofertilizers took shape, the benefits which can be achieved, and the challenges which nanofertilizers face for further development and real-world use, substantiated with the significant pieces of scientific evidence available so far.

A Perspective on Reproductive Toxicity of Metallic Nanomaterials

Nanotechnological tools have been greatly exploited in all possible fields. However, advancement of nanotechnology has raised concern about their adverse effects on human and environment. These deleterious effects cannot be ignored and need to be explored due to safety purpose. Several recent studies have demonstrated possible health hazard of nanoparticles on organism. Moreover, studies showed that toxicity of metallic nanomaterial could also lead to reproductive toxicity. Various deleterious effects have demonstrated decreased sperm motility, increased abnormal spermatozoa, altered sperm count, and altered sperm morphology. Morphological and ultrastructural changes also have been reported due to the accumulation of these nanomaterials in reproductive organs. Nonetheless, studies also suggest crossing of metallic nanoparticles through blood testes barrier and generation of oxidative stress which plays major role in reproductive toxicity. In the present study, we have incorporated updated information by gathering all available literature about various metallic nanomaterials and risk related to reproductive system.

PHYSIOLOGICAL AND HISTOLOGICAL STUDY OF THE CALCIUM OXIDE NANOPARTICLES EFFECT ON THE TESTIS OF MALE WISTER RATS

OBJECTIVE

The aim: The study carried out to determine the effect of the Calcium Oxide Nano Particles on the male rats. In this study were used calcium oxide nano powder to enhancing apoptosis in germ cells and disrupting hormonal regulation of reproductive processes in the adult male rats.

PATIENTS AND METHODS

Materials and methods: The experiment using nine male rats, were distributed into three groups. Group one A was doses orally of Calcium Oxide Nano Particles 50 mg/kg of body weight, while group two B was doses orally of Calcium Oxide Nano Particles 100 mg/kg of body weight; also, group three C were a control C group treated with 0.9% saline only, these orally doses continuous 10 days. After 10 days blood samples collected and all rats were euthanatized and the weights, histological changes and hormonal analysis were conducted.

RESULTS

Results: Results show a significantly increased at p<0.05 for both groups A & B compare with control C in weight of testis tissue and the level of testosterone hormone, also histology changes in testis of treatment rats include: necrosis of spermatogonia, primary spermoocyte and spermatids in both groups compared to control group.

CONCLUSION

Conclusions: Through the study, it is recommended to use medium or low doses of CaO NPs that can be used as a testicular tonic and urge it to increase production of the Testosterone hormone.

Advances in genotoxicity of titanium dioxide nanoparticles in vivo and in vitro

Titanium dioxide nanoparticles (TiO₂ NPs) are currently one of the most widely used nanomaterials. Due to an increasing scope of applications, the exposure of humans to TiO₂ NP is inevitable, such as entering the body through the mouth with food additives or drugs, invading the damaged skin with cosmetics, and entering the body through the respiratory tract during the process of production and handling. Compared with TiO₂ coarse particles, TiO₂ NPs have stronger conductivity, reaction activity, photocatalysis, and permeability, which may lead to greater toxicity to organisms. Given that TiO₂ was classified as a category 2B carcinogen (possibly carcinogenic to humans), the genotoxicity of TiO₂ NPs has become the focus of attention. There have been a series of previous studies investigating the potential genotoxicity of TiO₂ NPs, but the existing research results are still controversial and difficult to conclude. More than half of studies have shown that TiO₂ NPs can cause genotoxicity, suggesting that TiO₂ NPs are likely to be genotoxic to humans. And the genotoxicity of TiO₂ NPs is closely related to the exposure concentration, mode and time, and experimental cells/animals as well as its physicochemical properties (crystal type, size, and shape). This review summarized the latest research progress of related genotoxic effects through in vivo studies and in vitro cell tests, hoping to provide ideas for the evaluation of TiO₂ NPs genotoxicity.

Advances in endocrine toxicity of nanomaterials and mechanism in hormone secretion disorders

The size of nanoparticles is about 1-100 nm. People are exposed to nanoparticles in environmental pollutants from ancient times to the present. With the maturity of nanotechnology in the past two decades, the production of manufactured nanomaterials is rapidly increasing and they are used in a wide range of aerospace, medicine, food, and industrial applications. However, both natural and manufactured nanomaterials have been proved to pose a threat to diverse organs and systems. The endocrine system is critical to maintaining homeostasis. Endocrine disorders are associated with many diseases, including cancer, reduced fertility, and metabolic diseases. Therefore, we review the literatures dealing with the endocrine toxicity of nanomaterial. This review provides an exhaustive description of toxic effects of several common nanomaterials in the endocrine system; more involved are reproductive endocrinology. Then physicochemical factors that determine the endocrine toxicity of nanomaterials are discussed. Furthermore, oxidative stress, changes in steroid production and metabolic enzymes, organelle disruption, and alterations in signal pathways are introduced as potential mechanisms that may cause changes in hormone levels. Finally, we suggest that a risk assessment of endocrine toxicity based on standard procedures and consideration of endocrine disrupting effects of nanomaterials in the field and its environmental and population effects could be future research directions for endocrine toxicity of nanomaterials.

Titanium dioxide nanoparticles perturb the blood-testis barrier via disruption of actin-based cell adhesive function

As one of the most commonly used nanoparticles, titanium dioxide nanoparticles (TiO₂-NPs) are widely used as coating reagents in cosmetics, medicine and other industries. The increasing risk of exposure to TiO₂-NPs raises concerns about their safety. In this study, we investigated the mechanism by which TiO₂-NPs cross the blood-testis barrier (BTB). TM-4 cells were selected as an in vitro Sertoli cell model of BTB. Cell viability, cell morphological changes, apoptosis, oxidative damage, and the expression levels of actin regulatory and tight junction (TJ) proteins were assessed in TM-4 cells treated with 3-nm and 24-nm TiO₂-NPs. Cells treated with 3-nm TiO₂-NPs exhibited increased cytotoxicity and decreased Annexin II expression, whereas cells treated with 24-nm TiO₂-NPs exhibited increased Arp 3 and c-Src expression. Both TiO₂-NPs induced significant oxidative stress, decreased the expression of TJ proteins (occludin, ZO-1 and claudin 5), damaged the TJ structure, and exhibited enlarged gaps between TM-4 cells. Our results indicated that both TiO₂-NPs crossed the BTB by disrupting actin-based adhesive junctions of TM-4 cells; however, apoptosis was not observed. Our results provide new insights into how TiO₂-NPs cross the BTB.

Inhibition of testosterone synthesis induced by oral TiO2 NPs is associated with ROS-MAPK(ERK1/2)-StAR signaling pathway in SD rat

Titanium dioxide nanoparticles (TiO₂ NPs) have been widely used in food, medical, and other fields; their reproductive toxicity has been reported in numerous studies. However, the relevant toxicity mechanism still requires further exploration. In this paper, the effect of oral exposure to 500 mg/kg TiO₂ NPs (anatase and rutile) in adult male SD rats was studied over 3 and 7 days. Results showed that the total sperm count and testosterone level of 7 days of exposure in serum decreased in the experimental group. Testicular tissue lesions, such as disappearance of Leydig cells, disorder of arrangement of spermatogenic cells in the lumen of convoluted seminiferous tubules, and disorder of arrangement of germ cells, were observed. Meanwhile, the expression of steroidogenic acute regulatory (StAR; the key factors of testosterone synthesis), MAPK (ERK1/2), and phosphorylated ERK1/2 in testes of SD rats after exposure to TiO₂ NPs for 7 days decreased, while the malondialdehyde content increased and superoxide dismutase activity decreased in serum. The present study showed that TiO₂ NPs could cause reproductive toxicity. Notably, anatase is more toxic than rutile. In addition, exposure to 500 mg/kg TiO₂ NPs for 7 days inhibited testosterone synthesis in male rat, which may be related to the reactive oxygen species (ROS)-MAPK (ERK1/2)-StAR signal pathway. Warning that the use of TiO₂ NPs should be regulated.

Metal Oxide Nanoparticles: Evidence of Adverse Effects on the Male Reproductive System

Metal oxide nanoparticles (MONPs) are inorganic materials that have become a valuable tool for many industrial sectors, especially in healthcare, due to their versatility, unique intrinsic properties, and relatively inexpensive production cost. As a consequence of their wide applications, human exposure to MONPs has increased dramatically. More recently, their use has become somehow controversial. On one hand, MONPs can interact with cellular macromolecules, which makes them useful platforms for diagnostic and therapeutic interventions. On the other hand, research suggests that these MONPs can cross the blood–testis barrier and accumulate in the testis. Although it has been demonstrated that some MONPs have protective effects on male germ cells, contradictory reports suggest that these nanoparticles compromise male fertility by interfering with spermatogenesis. In fact, in vitro and in vivo studies indicate that exposure to MONPs could induce the overproduction of reactive oxygen species, resulting in oxidative stress, which is the main suggested molecular mechanism that leads to germ cells’ toxicity. The latter results in subsequent damage to proteins, cell membranes, and DNA, which ultimately may lead to the impairment of the male reproductive system. The present manuscript overviews the therapeutic potential of MONPs and their biomedical applications, followed by a critical view of their potential risks in mammalian male fertility, as suggested by recent scientific literature.

Can nanomaterials induce reproductive toxicity in male mammals? A historical and critical review

The nanotechnology enabled the development of nanomaterials (NMs) with a variety of industrial, biomedical, and consumer applications. However, the mechanism of action (MoA) and toxicity of NMs remain unclear, especially in the male reproductive system. Thus, this study aimed to perform a bibliometric and systematic review of the literature on the toxic effects of different types of NMs on the male reproductive system and function in mammalian models. A series of 236 articles related to the in vitro and in vivo reproductive toxicity of NMs in mammalian models were analyzed. The data concerning the bioaccumulation, experimental conditions (types of NMs, species, cell lines, exposure period, and routes of exposure), and the MoA and toxicity of NMs were summarized and discussed. Results showed that this field of research began in 2005 and has experienced an exponential increase since 2012. Revised data confirmed that the NMs have the ability to cross the blood-testis barrier and bioaccumulate in several organs of the male reproductive system, such as testis, prostate, epididymis, and seminal vesicle. A similar MoA and toxicity were observed after in vitro and in vivo exposure to NMs. The NM reproductive toxicity was mainly related to ROS production, oxidative stress, DNA damage and apoptosis. In conclusion, the NM exposure induces bioaccumulation and toxic effects on male reproductive system of mammal models, confirming its potential risk to human and environmental health. The knowledge concerning the NM reproductive toxicity contributes to safety and sustainable use of nanotechnology.

EFSA Panel on Food Additives and Flavourings (FAF), Younes M, Aquilina G, Castle L, Engel K, Fowler P, Frutos Fernandez MJ, Fürst P, Gundert‐Remy U, Gürtler R, Husøy T, Manco M, Mennes W, Moldeus P, Passamonti S, Shah R, Waalkens‐Berendsen I, Wölfle D, Corsini E, Cubadda F, De Groot D, FitzGerald R, Gunnare S, Gutleb AC, Mast J, Mortensen A, Oomen A, Piersma A, Plichta V, Ulbrich B, Van Loveren H, Benford D, Bignami M, Bolognesi C, Crebelli R, Dusinska M, Marcon F, Nielsen E, Schlatter J, Vleminckx C, Barmaz S, Carfí M, Civitella C, Giarola A, Rincon AM, Serafimova R, Smeraldi C, Tarazona J, Tard A, Wright M. Safety assessment of titanium dioxide (E171) as a food additive

The present opinion deals with an updated safety assessment of the food additive titanium dioxide (E 171) based on new relevant scientific evidence considered by the Panel to be reliable, including data obtained with TiO2 nanoparticles (NPs) and data from an extended one-generation reproductive toxicity (EOGRT) study. Less than 50% of constituent particles by number in E 171 have a minimum external dimension < 100 nm. In addition, the Panel noted that constituent particles < 30 nm amounted to less than 1% of particles by number. The Panel therefore considered that studies with TiO2 NPs < 30 nm were of limited relevance to the safety assessment of E 171. The Panel concluded that although gastrointestinal absorption of TiO2 particles is low, they may accumulate in the body. Studies on general and organ toxicity did not indicate adverse effects with either E 171 up to a dose of 1,000 mg/kg body weight (bw) per day or with TiO2 NPs (> 30 nm) up to the highest dose tested of 100 mg/kg bw per day. No effects on reproductive and developmental toxicity were observed up to a dose of 1,000 mg E 171/kg bw per day, the highest dose tested in the EOGRT study. However, observations of potential immunotoxicity and inflammation with E 171 and potential neurotoxicity with TiO2 NPs, together with the potential induction of aberrant crypt foci with E 171, may indicate adverse effects. With respect to genotoxicity, the Panel concluded that TiO2 particles have the potential to induce DNA strand breaks and chromosomal damage, but not gene mutations. No clear correlation was observed between the physico-chemical properties of TiO2 particles and the outcome of either in vitro or in vivo genotoxicity assays. A concern for genotoxicity of TiO2 particles that may be present in E 171 could therefore not be ruled out. Several modes of action for the genotoxicity may operate in parallel and the relative contributions of different molecular mechanisms elicited by TiO2 particles are not known. There was uncertainty as to whether a threshold mode of action could be assumed. In addition, a cut-off value for TiO2 particle size with respect to genotoxicity could not be identified. No appropriately designed study was available to investigate the potential carcinogenic effects of TiO2 NPs. Based on all the evidence available, a concern for genotoxicity could not be ruled out, and given the many uncertainties, the Panel concluded that E 171 can no longer be considered as safe when used as a food additive.

Nanoparticles in pregnancy: the next frontier in reproductive therapeutics

BACKGROUND

Nanotechnology involves the engineering of structures on a molecular level. Nanomedicine and nano-delivery systems have been designed to deliver therapeutic agents to a target site or organ in a controlled manner, maximizing efficacy while minimizing off-target effects of the therapeutic agent administered. In both reproductive medicine and obstetrics, developing innovative therapeutics is often tempered by fears of damage to the gamete, embryo or developing foetus or of negatively impacting a woman's reproductive potential. Thus, nanomedicine delivery systems may provide alternative targeted intervention strategies, treating the source of the disease and minimizing long-term consequences for the mother and/or her foetus.

OBJECTIVE AND RATIONALE

This review summarizes the current state of nanomedicine technology in reproductive medicine and obstetrics, including safety, potential applications, future directions and the hurdles for translation.

SEARCH METHODS

A comprehensive electronic literature search of PubMed and Web of Science databases was performed to identify studies published in English up until February 2020. Relevant keywords were used to obtain information regarding use of nanoparticle technology in fertility and gene therapy, early pregnancy complications (ectopic pregnancy and gestational trophoblastic disease) and obstetric complications (preeclampsia, foetal growth restriction, preterm birth and gestational diabetes) and for selective treatment of the mother or foetus. Safety of specific nanoparticles to the gamete, embryo and foetus was also investigated.

OUTCOMES

Pre-clinical research in the development of nanoparticle therapeutic delivery is being undertaken in many fields of reproductive medicine. Non-hormonal-targeted nanoparticle therapy for fibroids and endometriosis may provide fertility-sparing medical management. Delivery of interventions via nanotechnology provides opportunities for gene manipulation and delivery in mammalian gametes. Targeting cytotoxic treatments to early pregnancy tissue provides an alternative approach to manage ectopic pregnancies and gestational trophoblastic disease. In pregnancy, nanotherapeutic delivery offers options to stably deliver silencing RNA and microRNA inhibitors to the placenta to regulate gene expression, opening doors to novel genetic treatments for preeclampsia and foetal growth restriction. Restricting delivery of teratogenic drugs to the maternal compartment (such as warfarin) may reduce risks to the foetus. Alternatively, targeted delivery of drugs to the foetus (such as those to treat foetal arrythmias) may minimize side effects for the mother.

WIDER IMPLICATIONS

We expect that further development of targeted therapies using nanoparticles in a reproductive setting has promise to eventually allow safe and directed treatments for conditions impacting the health and reproductive capacity of women and for the management of pregnancy and serious pregnancy complications.

Perspectives of Nanoparticles in Male Infertility: Evidence for Induced Abnormalities in Sperm Production

Advancement in the field of nanotechnology has prompted the need to elucidate the deleterious effects of nanoparticles (NPs) on reproductive health. Many studies have reported on the health safety issues related to NPs by investigating their exposure routes, deposition and toxic effects on different primary and secondary organs but few studies have focused on NPs' deposition in reproductive organs. Noteworthy, even fewer studies have dealt with the toxic effects of NPs on reproductive indices and sperm parameters (such as sperm number, motility and morphology) by evaluating, for instance, the histopathology of seminiferous tubules and testosterone levels. To date, the research suggests that NPs can easily cross the blood testes barrier and, after accumulation in the testis, induce adverse effects on spermatogenesis. This review aims to summarize the available literature on the risks induced by NPs on the male reproductive system.

Alteration of sperm parameters and reproductive hormones in Swiss mice via oxidative stress after co-exposure to titanium dioxide and zinc oxide nanoparticles

In this study, Swiss male mice were intraperitoneally administered with titanium dioxide (TiO₂ ) and zinc oxide (ZnO) nanoparticles (NPs) and their mixture (1:1) at doses between 9.38 and 75 mg/kg for 5 weeks to evaluate reproductive toxicity. Both NPs and their mixture significantly (p < .001) altered sperm motility, reduced sperm numbers and increased abnormalities, while their mixture induced more sperm abnormalities than either TiO₂ NPs or ZnO NPs. Both NPs and their mixture significantly (p < .05) reduced the LH level, while ZnO NPs alone and their mixture (p < .001) increased the testosterone levels at tested doses. The testes of exposed mice showed pathological changes and altered histomorphometrics. TiO₂ NPs and ZnO NPs individually induced a significant (p < .01) reduction in SOD and CAT activities, while the mixture significantly (p < .001) decreased CAT activity and increased SOD activity. TiO₂ NPs alone at 9.38 mg/kg induced a significant (p < .001) reduction in the GSH level, while both NPs and their mixture increased the MDA level significantly (p < .05). The data showed that the mixture had a synergistic interaction to induce testicular damage. Overall, oxidative stress may be involved in the NP-mediated testicular damage observed.

Oxidative Damage Induced by Nano-titanium Dioxide in Rats and Mice: a Systematic Review and Meta-analysis

Nano-titanium dioxide is a kind of widely used nanomaterial that exhibits various adverse outcomes. However, the role of oxidative stress in this regard remains controversial. This study aimed to evaluate whether oxidative stress is one of the toxicity mechanisms induced by nano-titanium dioxide in rats and mice model. In this meta-analysis, 64 relevant publications were included through detailed database search. The pooled results showed that nano-titanium dioxide exposure could promote the expression of oxidants, such as malonaldehyde (MDA), 8-hydroxy-2-deoxyguanosine (8-OHdG), superoxide anion (O₂^-), and hydrogen peroxide (H₂O₂). Meanwhile, the levels of antioxidant-related enzymes and molecules, such as superoxide dismutase (SOD), glutathione (GSH), glutathione peroxidase (GPx), and catalase (CAT), were reduced. Subgroup analysis revealed that different intervention routes, exposure periods, exposure dosages, and sample sources could affect the oxidative stress when exposed to nano-titanium dioxide. It was worth noting that the levels of MDA, 8-OHdG, and GSH significantly increased (P < 0.05) when the particle size of nano-titanium dioxide was < 10 nm, whereas H₂O₂, SOD, and GPx showed the highest effect at 10-40 nm. This study indicated that nano-titanium dioxide could cause oxidative damage by affecting the levels of enzymes and molecules involved in oxidative stress in rats and mice. And these results could provide a reference for studies of the toxicity mechanism induced by nano-titanium dioxide in the future.

Repeated administrations of Mn3O4 nanoparticles cause testis damage and fertility decrease through PPAR-signaling pathway

Potential health hazards of nanomaterials on male reproductive system have received raising concerns. Even though Mn₃O₄ nanoparticles (Mn₃O₄-NPs) is highly effective in clinical diagnostic and therapeutic applications of human disease, its potential toxic effect on the male reproductive system has not been reported. In this study, the testis damage and fertility decrease of male rats were conducted to testify the experimental reproductive injury induced by Mn₃O₄-NPs. After repeated tail vein injection with 10 mg/kg/week Mn₃O₄-NPs for 0, 60 and 120 days, Mn₃O₄-NPs accumulated in the testes resulted in oxidative stress and disorder of normal serum sex hormones. Experiments in vivo and in vitro indicated that mitochondria-mediated cell apoptosis were triggered via oxidative stress, demonstrated by the upregulation of malondialdehyde (MDA) and the depolarization of mitochondrial membrane potential. Notably, Mn₃O₄-NPs significantly resulted in a reduction of the quantity/quality of sperm and finally caused astonishing fertility decrease. Our preliminary result implied that the application of Mn₃O₄-NPs could be a double-edged sword and careful consideration should be given to the clinical uses.

Biodistribution, Clearance And Morphological Alterations Of Intravenously Administered Iron Oxide Nanoparticles In Male Wistar Rats

Introduction

Nanoparticles are used worldwide because of their unique properties, with large-scale application in various fields, such as medicine, cosmetics and industries. In view of their widespread use, the potential adverse effects of nanoparticles have become a significant cause for concern, in terms of not only human health and safety but also the environment. The present investigation focused on establishing the bioaccumulation patterns and ultrastructural changes induced by retained iron oxide nanoparticles (IONPs) in various target organs of rats.

Methods

Twenty-four male Wistar rats were randomly divided into four groups. Experimental animals were intravenously administered different doses of IONPs (7.5 mg/kg, 15 mg/kg and 30 mg/kg) once in a week for 4 weeks. Urine and feces samples were collected on a daily basis to assess nanoparticle clearance and analyzed via atomic absorption spectroscopy (AAS). At the end of the experiment, rats were euthanized and different organs, including spleen, liver, kidney, lung, heart, testis and brain, were dissected. Bioaccumulation of iron in organs and ultrastructural changes induced by IONPs were determined.

Results

The maximal concentration of iron was detected in spleen and minimal concentration in the brain. The level of iron accumulation in organs was as follows: spleen>blood>liver>kidney>lung>heart>testis>brain. The excretion profile in urine revealed maximum excretion on the day following administration that was maintained until day 28, whereas the iron content in feces remained high during the first three days after injection. A similar pattern was observed throughout the duration of the experiment. Ultrastructural alterations were detected in spleen, kidney, lung, heart, testis, brain and liver, indicative of cellular damage induced by accumulating nanoparticles in these organs.

Conclusion

Intravenous administration of IONPs results in ultrastructural changes and dose-dependent bioaccumulation in different organs of rats.

Exposure to PbSe Nanoparticles and Male Reproductive Damage in a Rat Model

PbSe nanoparticles (PbSe-NPs) attract ever-growing interest owing to their great promise in various fields. However, potential toxic effects of PbSe-NPs on male reproductive systems have not been reported. This study aimed to determine whether early-life exposure to PbSe-NPs could affect male reproductive systems and other related health effects in rats. The male rats were intraperitoneally injected with 10 mg/kg/week PbSe-NPs for 60 days followed by a series of reproductive-related analyses. We found that the nanoparticles could accumulate in testes in a size-dependent manner. Furthermore, accumulation of PbSe-NPs resulted in oxidative stress and disorder of normal serum sex hormones. Endoplasmic reticulum and mitochondria-mediated cell apoptosis were triggered via oxidative stress, as shown by upregulation of cytoplasmic Cyt-c, Bax, cleaved Caspase-3, GRP78, and Caspase-12. Notably, PbSe-NP administration led to reduction in the quantity and quality of sperm, which caused a great fertility decrease. In contrast, released Pb²⁺ from PbSe-NPs did not result in any testis toxicity and fertility declines. These results demonstrate that PbSe-NPs could cause severe reproductive toxicity in a size-dependent manner and these toxic effects should be responsible for PbSe-NPs themselves rather than released Pb²⁺. The application of PbSe-NPs might be a double-edged sword, and corresponding measures should be taken before use.

Anticancer properties of green-synthesised zinc oxide nanoparticles using Hyssopus officinalis extract on prostate carcinoma cells and its effects on testicular damage and spermatogenesis in Balb/C mice

The unclear bio-safety issue and potential risk of nanoparticles (NPs) on various organelles can be considered as a major challenge. In the present study, we have assessed the green synthesis of ZnO nanoparticles using Hyssop (Hyssopus officinalis) extract and their effects on PC3 cell line and BALB/c mice model. The cytotoxicity of the ZnO-NPs was assessed on PC3 cell line by MTT test after characterisation. Apoptotic effect of ZnO-NPs was determined by in vitro AO/PI staining. The histopathological assessments and determination of LH and FSH levels carried out as in vivo analysis in BALB/c adult male mice. The expression of major genes involved in spermatogenesis and sperm maturation (Adam3, Prm1, Spata19, Tnp2, Gpx5) were also analysed. The obtained result demonstrated that the IC₅₀ for PC3 cell line treated with green-synthesised ZnO-NPs during 24 and 48 hr was reported 8.07 and 5 µg/ml respectively. Meanwhile, the induced apoptosis was recorded 26.6% ± 0.05, 44% ± 0.12 and 80% ± 0.07 of PC3 cells. The results of gene expression analysis revealed that the increase in the concentration of ZnO-NPs significantly (p < .05) down-regulated the Adam3, Prm1, Spata-19, Tnp2 and Gpx5 genes. The overall results of this research elucidated that ZnO-NPs impaired spermatogenesis, sperm maturation process and sperm motility.

Amelioration of titanium dioxide nanoparticle reprotoxicity by the antioxidants morin and rutin

The present study aimed to examine the ameliorative effects of morin and rutin on the reproductive toxicity induced by titanium dioxide nanoparticles (TiO₂NPs) in male rats. A total of seventy adult male Sprague-Dawley rats were randomly divided into seven groups, each comprising ten rats. Nanoreprotoxicity was induced by treating rats with TiO₂NPs at a dosage of 300 mg/kg body weight for 30 days. Morin (30 mg/kg body weight) and rutin (100 mg/kg body weight) were co-administered with or without TiO₂NPs to rats either individually or combined. Only distilled water was administered to the control group. The results showed that TiO₂NPs enhanced oxidative stress, indicated by reduced levels of antioxidants such as superoxide dismutase (SOD), catalase (CAT), and glutathione (GSH) in testicular tissues, and increased levels of the lipid peroxidation marker malondialdehyde (MDA). TiO₂NPs significantly reduced the levels of sex hormones (testosterone, FSH, and LH), reduced sperm motility, viability, and sperm cell count, and increased sperm abnormalities, in addition to damaging the testicular histological architecture. TiO₂NPs resulted in the downregulation of 17β-HSD and the upregulation of proapoptotic gene (Bax) transcripts in the testicular tissues. Conversely, morin and/or rutin had a protective effect on testicular tissue. They effectively counteracted TiO₂NP-induced oxidative damage and morphological injury in the testis by conserving the endogenous antioxidant mechanisms and scavenging free radicals. Thus, we suggest that morin and rutin could be used to alleviate the toxicity and oxidative damage associated with TiO₂NP intake.

Titanium dioxide nanoparticles induce COX-2 expression through ROS generation in human periodontal ligament cells

Titanium dioxide nanoparticles (TiO₂-NPs) are used to improve the aesthetic of toothpaste. While TiO₂-NPs have been used safely in toothpaste products for a long time, there haven't been studies to determine whether absorption of TiO₂-NPs by the mucous membranes in the mouth induces pathogenic conditions. Here, we assessed whether TiO₂-NPs induce cyclooxygenase-2 (COX-2) and investigated the molecular mechanisms underlying the pro-inflammatory effect of TiO₂-NPs on human periodontal ligament (PDL) cells. Treatment of PDL cells with TiO₂-NPs led to induction of both COX-2 mRNA and protein expression. TiO₂-NPs stimulated the nuclear translocation of nuclear factor-kappaB (NF-κB) as well as its DNA binding by inducing phosphorylation and subsequent degradation of the inhibitory protein IκBα in PDL cells. TiO₂-NPs treatment resulted in rapid activation of extracellular signal-regulated kinase (ERK)1/2 and Akt, which could be upstream of NF-κB. Treatment of PDL cells with both the MEK1/2 inhibitor U0126 and the PI3K inhibitor LY294002 strongly attenuated TiO₂-NPs-induced activation of NF-κB, and also the expression of COX-2. PDL cells treated with TiO₂-NPs exhibited increased accumulation of intracellular reactive oxygen species (ROS). Pretreatment of cells with ROS scavenger N-acetyl cysteine (NAC) abrogated the stimulatory effect of TiO₂-NPs on p65, p50, and COX-2 expression. In conclusion, ROS, concomitantly overproduced by TiO₂-NPs, induce COX-2 expression through activation of NF-κB signaling, which may contribute to the inflammatory effect of PDL cells.

Airway exposure to TiO2 nanoparticles and quartz and effects on sperm counts and testosterone levels in male mice

Several types of engineered nanoparticles (ENP) have been shown to adversely affect male reproduction in rodent studies, but the airway route of exposure has been little investigated. This precludes adequate risk assessment of ENP exposure in occupational settings. Titanium dioxide nanoparticles (TiO₂ NP) have been shown to affect total sperm count in adult male mice after intravenous and oral administration. This study aimed to investigate whether also airway exposure would affect sperm counts in male mice. Mature C57BL/6J mice were intratracheally instilled with 63 μg of rutile nanosized TiO₂, once weekly for seven weeks. Respirable α-quartz (SRM1878a) was included at a similar dose level as a positive control for pulmonary inflammation. BALF cell composition showed neutrophil granulocyte influx as indication of pulmonary inflammation in animals exposed to TiO₂ NP and α-quartz, but none of the particle exposures affected weight of testes or the epididymis, sperm counts or plasma testosterone when assessed at termination of the study.

Reduction of the Cytotoxicity of Copper (II) Oxide Nanoparticles by Coating with a Surface-Binding Peptide

Copper (II) oxide nanoparticles (CuO-NPs) have been studied as potential antimicrobial agents, similar to silver or platinum nanoparticles. However, the use of excess NPs is limited by their safety and toxicity in beneficial microflora and human cells. In this study, we evaluated the cytotoxicity of CuO-NPs by coating with a novel cyclic peptide, CuO binding peptide 1 (CuBP1), cyclic-SCATPFSPQVCS, which binds to the surface of CuO-NPs. CuBP1 was identified using biopanning of a T7 phage display system and was found to promote the aggregation of CuO-NPs under mild conditions. The treated CuO-NPs with CuBP1 caused the reduction of the cytotoxicity against Escherichia coli, Lactobacillus helveticus, and five other microorganisms, including bacteria and eukaryotes. Similar effects were also demonstrated against human embryonic kidney (HEK293) cells in vitro. Our findings suggested that the CuO-NPs coated with a surface-binding peptide may have applications as a safe antimicrobial agent without excessive cytotoxic activity against beneficial microflora and human cells. Moreover, a similar tendency may be achieved with other metal particles, such as silver or platinum NPs, by using optimal metal binding peptides.

NiO-nanoparticles induce reduced phytotoxic hazards in wheat (Triticum aestivum L.) grown under future climate CO2

Due to industrialization and expansion of nanotechnology, ecosystem contamination by nanoparticles is likely. Overall, nanoparticles accumulate in environmental matrices and induce phytotoxicity, however future climate (elevated CO₂ (eCO₂)) may affect the distribution of nanoparticles in ecosystems and alter their impact on plants. In the current study, nickel oxide nanoparticles (NiO-NPs) with an average diameter of 54 nm were synthesized by chemical pericipitation method using Triton X-100 and characterized by scanning electron microscopy (SEM), UV-VIS spectroscopy and Fourier transform infrared spectroscopy (FTIR). We have investigated the impact of NiO-NPs at a concentration of 120 mg kg^-1 soil, selected based on the results of a preliminary experiment, on accumulation of Ni ions in wheat (Triticum aestivum L.) and how that could influence plant growth, photosynthesis and redox homeostasis under two CO₂ scenarios, ambient (aCO_2, 400 ppm) and eCO₂ (620 ppm). NiO-NPs alone reduced whole plant growth, inhibited photosynthesis and increased the levels of antioxidants. However, improved defense system was not enough to lessen photorespiration induced H₂O₂ accumulation and oxidative damage (lipid and protein oxidation). Interestingly, eCO₂ significantly mitigated the phytotoxicity of NiO-NPs. Although, eCO₂ did not affect Ni accumulation and translocation in wheat, it promoted photosynthesis and inhibited photorespiration, resulting in reduced ROS production. Moreover, it further improved the antioxidant defense system and maintained ASC/DHA and GSH/GSSG redox balances. Organ specific responses to NiO-NPs and/or eCO₂ were indicated and confirmed by cluster analysis. Overall, we suggest that wheat plants will be more tolerant to NiO-NPs stress under future climate CO₂.

In vitro genotoxic effects of titanium dioxide nanoparticles (n-TiO2 ) in human sperm cells

Titanium dioxide nanoparticles (TiO₂ -NPs) are one of the most widely engineered nanoparticles used. The study has been focused on TiO ₂ -NPs genotoxic effects on human spermatozoa in vitro. TiO ₂ -NPs are able to cross the blood-testis barrier induced inflammation, cytotoxicity, and gene expression changes that lead to impairment of the male reproductive system. This study presents new data about DNA damage in human sperms exposed in vitro to two n-TiO ₂ concentrations (1 µg/L and 10 µg/L) for different times and the putative role of reactive oxygen species (ROS) as mediators of n-TiO ₂ genotoxicity. Primary n-TiO ₂ characterization was performed by transmission electron microscopy. The dispersed state of the n-TiO ₂ in media was spectrophotometrically determined at 0, 24, 48, and 72 hr from the initial exposure. The genotoxicity has been highlighted by different experimental approaches (comet assay, terminal deoxynucleotidyl transferase dUTP nick end labeling [TUNEL] test, DCF assay, random amplification of polymorphic DNA polymerase chain reaction [RAPD-PCR]). The comet assay showed a statistically significant loss of sperm DNA integrity after 30 min of exposure. Increased threshold of sperm DNA fragmentation was highlighted after 30 min of exposure by the TUNEL Test. Also, the RAPD-PCR analysis showed a variation in the polymorphic profiles of the sperm DNA exposed to n-TiO ₂ . The evidence from the DCF assay showed a statistically significant increase in intracellular ROS linked to n-TiO ₂ exposure. This research provides the evaluation of n-TiO ₂ potential genotoxicity on human sperm that probably occurs through the production of intracellular ROS.

Perspectives of nanotechnology in male fertility and sperm function

Recent advances in nanotechnology have tremendously expanded its possible applications in biomedicine. Although, the effects of nanoparticles (NPs) at cellular and tissue levels have not been fully understood, some of these biological effects might be employed in assisted reproduction to improve male fertility particularly by enhancing sperm cell quality either in vivo or in vitro. This review summarises the available literature regarding the potential applications of nanomaterials in farm animal reproduction, with a specific focus on the male gamete and on different strategies to improve breeding performances, transgenesis and targeted delivery of substances to a sperm cell. Antioxidant, antimicrobial properties and special surface binding ligand functionalization and their applications for sperm processing and cryopreservation have been reviewed. In addition, nanotoxicity and detrimental effects of NPs on sperm cells are also discussed due to the increasing concerns regarding the environmental impact of the expanding use of nanotechnologies on reproduction.

Suppression of testosterone production by nanoparticulate TiO2 is associated with ERK1/2-PKA-PKC signaling pathways in rat primary cultured Leydig cells

Background

Nanoparticulate titanium dioxide (nano-TiO₂) enters the body through various routes and causes organ damage. Exposure to nano-TiO₂ is reported to cause testicular injury in mice or rats and decrease testosterone synthesis, sperm number, and motility. Importantly, nano-TiO₂ suppresses testosterone production by Leydig cells (LCs) and impairs the reproductive capacity of animals.

Methods

In an attempt to establish the molecular mechanisms underlying the inhibitory effect of nano-TiO₂ on testosterone synthesis, primary cultured rat LCs were exposed to varying concentrations of nano-TiO₂ (0, 10, 20, and 40 µg/mL) for 24 hours, and alterations in cell viability, cell injury, testosterone production, testosterone-related factors (StAR, 3βHSD, P450scc, SR-BI, and DAX1), and signaling molecules (ERK1/2, PKA, and PKC) were investigated.

Results

The data show that nano-TiO₂ crosses the membrane into the cytoplasm or nucleus, triggering cellular vacuolization and nuclear condensation. LC viability decreased in a time-dependent manner at the same nano-TiO₂ concentration, nano-TiO₂ treatment (10, 20, and 40 µg/mL) decreased MMP (36.13%, 45.26%, and 79.63%), testosterone levels (11.40% and 44.93%), StAR (14.7%, 44.11%, and 72.05%), 3βHSD (26.56%, 50%, and 79.69%), pERK1/2 (27.83%, 63.61%, and 78.89%), PKA (47.26%, 70.54%, and 85.61%), PKC (30%, 50%, and 71%), SR-BI (16.41%, 41.79%, and 67.16%), and P450scc (39.41%, 55.26%, and 86.84%), and upregulated DAX1 (1.31-, 1.63-, and 3.18-fold) in primary cultured rat LCs.

Conclusion

Our collective findings indicated that nano-TiO₂-mediated suppression of testosterone in LCs was associated with regulation of ERK1/2–PKA–PKC signaling pathways.

Acute Heat Stress Changes Protein Expression in the Testes of a Broiler-Type Strain of Taiwan Country Chickens

Heat stress leads to decreased fertility in roosters. This study investigated the global protein expression in response to acute heat stress in the testes of a broiler-type strain of Taiwan country chickens (TCCs). Twelve 45-week-old roosters were randomly allocated to the control group maintained at 25°C, and three groups subjected to acute heat stress at 38°C for 4 h, with 0, 2, and 6 h of recovery, respectively. Testis samples were collected for hematoxylin and eosin staining, apoptosis assay, and protein analysis. The results revealed 101 protein spots that differed significantly from the control following exposure to acute heat stress. The proteins that were differentially expressed participated mainly in protein metabolism and other metabolic processes, responses to stimuli, apoptosis, cellular organization, and spermatogenesis. Proteins that negatively regulate apoptosis were downregulated and proteins involved in autophagy and major heat shock proteins (HSP90α, HSPA5, and HSPA8) were upregulated in the testes of heat-stressed chickens. In conclusion, acute heat stress causes a change in protein expression in the testes of broiler-type B strain TCCs and may thus impair cell morphology, spermatogenesis, and apoptosis. The expression of heat shock proteins increased to attenuate the testicular injury induced by acute heat stress.