Silver nanoparticles effects on epididymal sperm in rats

Thiol-antioxidants interfere with assessing silver nanoparticle cytotoxicity

Many studies have shown that silver nanoparticles (AgNP) induce oxidative stress, and it is commonly assumed that this is the main mechanism of AgNP cytotoxicity. Most of these studies rely on antioxidants to establish this cause-and-effect relationship; nevertheless, details on how these antioxidants interact with the AgNP are often overlooked. This work aimed to investigate the molecular mechanisms underlying the use of antioxidants with AgNP nanoparticles. Thus, we studied the molecular interaction between the thiol-antioxidants (N-acetyl-L-Cysteine, L-Cysteine, and glutathione) or non-thiol-antioxidants (Trolox) with chemically and biologically synthesized AgNP. Both antioxidants could mitigate ROS production in Huh-7 hepatocarcinoma cells, but only thiol-antioxidants could prevent the cytotoxic effect, directly binding to the AgNP leading to aggregation. Our findings show that data interpretation might not be straightforward when using thiol-antioxidants to study the interactions between metallic nanoparticles and cells. This artifact exemplifies potential pitfalls that could hinder the progress of nanotechnology and the understanding of the nanotoxicity mechanism.

Transfer of orally administered ZnO:Eu nanoparticles through the blood-testis barrier: the effect on kinetic sperm parameters and apoptosis in mice testes

Zinc-based nanoparticles are promising materials for various applications, including in biomedicine. The aim of our study was to determine the effect of fluorescent europium-doped zinc oxide nanoparticles (ZnO:Eu NPs) on sperm parameters, cell apoptosis and integrity of the blood-testis barrier (BTB) in mice. Nanostructures were orally administered to adult mice (n = 34). Animals were sacrificed after 3 h, 24 h, 7 d and 14 d following oral administration. Sperm was collected and analysed for viability and kinetic parameters. Collected testes were quantitatively analysed for accumulation of ZnO:Eu NPs. Microscopic evaluation based on immunofluorescence and histopathological studies were also conducted. Results showed that ZnO:Eu NPs were able to overcome the BTB with their subsequent accumulation in the testis. No toxic or pro-apoptotic effects of nanoparticles on the male reproductive system were observed. The results suggested that ZnO:Eu NPs were able to accumulate in the testis with no negative impact on sperm parameters, tissue architecture or the integrity of the BTB.

Morin ameliorates the testicular apoptosis, oxidative stress, and impact on blood-testis barrier induced by photo-extracellularly synthesized silver nanoparticles

Silver nanoparticles (AgNPs) have been widely produced for different industrial purposes. Recently, biogenic synthesis of AgNPs has emerged although the extent of effects from exposure, oral exposure in particular, to nanomaterials synthesized in such a manner remains elusive. The main objective of this study was to evaluate the effects of oral administration of a dose of 50 mg/Kg body weight AgNPs biosynthesized in baker's yeast (Saccharomyces cerevisiae) over a period of eight weeks on the reproductive performance and the possibility of a protective effect through co-administration of morin. Forty-eight male Sprague-Dawley rats were used in four experimental groups (control, morin-treated group, AgNP-treated, and AgNP + morin co-treatment). AgNPs produced no significant alteration in daily food intake or body weight. Both the absolute and relative testicular weights were significantly reduced but not the epididymal weight. Also, serum levels of urea, creatinine, uric acid, and liver enzymes were significantly elevated. Furthermore, AgNPs significantly downregulated the hypothalamic-pituitary-gonadal axis. This corresponds to lower motility and viability percent, reduced sperm concentration, and a higher abnormality ratio as well as a prominent alteration in the blood-testis barrier (BTB) and testicular histology and induction of testicular apoptosis and oxidative stress. The supplementation of morin evidently restored most of the reproductive characters to its physiological range. We can conclude that exposure to the biologically synthesized AgNPs for an extended period of time has proven to be a health risk that can be ameliorated via oral administration of some bioactive agents including morin.

Silver nanoparticles testicular toxicity in rat

To evaluate the potential testicular toxicity induced by silver nanoparticles (AgNPs) in Sprague Dawley rate. The protocol study was designed as follows: G1: 30 adult male rats were kept as control. G2: 30 adult male rats were administered 5.36 mg/kg of AgNPs orally, twice weekly for six months. G3: 30 adult male rats were administered 13.4 mg/kg of AgNPs orally, twice weekly for six months. The results of hormonal assay revealed that a significant decrease in testosterone level while a significant increase in LH level was obtained. The testicular homogenate showed a significant decrease in SOD activity accompanied by a significant increase in MDA level in both G2 and G3 in comparison with the control in a dose-response relationship. Sperm viability indicates a significant decrease in rats in G2 and G3 groups. A significant decrease in DNA chromatin integrity % was obtained in rats of G3 in comparison with G2 and control. The semithin and TEM sections of the testis of G2 and G3 groups showed Sertoli cells have vacuolations with a disturbance in the arrangement and the staining affinity of spermatogenic cells. The spermatogonia appeared with a moderate electron density of the nucleus and cytoplasm. The acrosome and its cap become oval and light electron dens of spermatid cells.

Ex vivo detection and quantification of gold nanoparticles in human seminal and follicular fluids

Increasing consumption of engineered nanoparticles and occupational exposure to novel, ultrafine airborne particles during the last decades has coincided with deterioration of sperm parameters and delayed fecundity. In order to prevent possible adverse health effects and ensure a sustainable growth for the nanoparticle industry, the ability to investigate the nanosized, mineralogical load of human reproductive systems is becoming a real clinical need. Toward this goal, the current study proposes two methods for the detection and quantification of engineered nanoparticles in human follicular and seminal fluid, developed with the use of well-defined 60 nm Au particles. Despite the complexity of these biological fluids, simple physical and chemical treatments allow for the precise quantification of more than 50 and 70% wt of the spiked Au nanoparticles at low μg ml^-1 levels in follicular and seminal fluids, respectively. The use of electron microscopy for the detailed observation of the detected analytes is also enabled. The proposed method is applied on a small patient cohort in order to demonstrate its clinical applicability by exploring the differences in the metal and particulate content between patients with normal and low sperm count.

Potential adverse effects of nanoparticles on the reproductive system

With the vigorous development of nanometer-sized materials, nanoproducts are becoming widely used in all aspects of life. In medicine, nanoparticles (NPs) can be used as nanoscopic drug carriers and for nanoimaging technologies. Thus, substantial attention has been paid to the potential risks of NPs. Previous studies have shown that numerous types of NPs are able to pass certain biological barriers and exert toxic effects on crucial organs, such as the brain, liver, and kidney. Only recently, attention has been directed toward the reproductive toxicity of nanomaterials. NPs can pass through the blood–testis barrier, placental barrier, and epithelial barrier, which protect reproductive tissues, and then accumulate in reproductive organs. NP accumulation damages organs (testis, epididymis, ovary, and uterus) by destroying Sertoli cells, Leydig cells, and germ cells, causing reproductive organ dysfunction that adversely affects sperm quality, quantity, morphology, and motility or reduces the number of mature oocytes and disrupts primary and secondary follicular development. In addition, NPs can disrupt the levels of secreted hormones, causing changes in sexual behavior. However, the current review primarily examines toxicological phenomena. The molecular mechanisms involved in NP toxicity to the reproductive system are not fully understood, but possible mechanisms include oxidative stress, apoptosis, inflammation, and genotoxicity. Previous studies have shown that NPs can increase inflammation, oxidative stress, and apoptosis and induce ROS, causing damage at the molecular and genetic levels which results in cytotoxicity. This review provides an understanding of the applications and toxicological effects of NPs on the reproductive system.

Potential adverse outcome pathway (AOP) of silver nanoparticles mediated reproductive toxicity in zebrafish

Recently, the augmented utilization of silver nanoparticles (AgNPs) resulted in increasingrates of its release to aquatic environment, which potentially caused adverse effects to aquatic organisms. Therefore, this study investigated - reproductive toxicity and associated potential adverse outcome pathway (AOP) in zebrafish after chronic exposure to AgNPs. To serve the purpose, three-month-old adult zebrafish were exposed to different concentrations (0, 10, 33 and 100 μg/L) of AgNPs for five weeks. Exposure to 33 and 100 μg/L of AgNPs significantly decreased the fecundity in female zebrafish, accompanied by increasing apoptotic cells in the ovarian and testicular tissue using TUNEL assay. Increasing tissue burdens of AgNPs and reactive oxygen species (ROS) production were also found in both ovary and testis after five-week exposure to AgNPs. To explore the mechanism of the apoptotic pathway, the transcription levels of various genes (bax, bcl-2, caspase-3, and caspase-9) associated with the mitochondrion-mediated apoptosis pathway were examined in zebrafish after exposure to AgNPs. The results showed that the expression patterns of all the investigated genes were altered to some extent. These findings demonstrated that AgNPs exposure caused oxidative stress, induced germ cells apoptosis via mitochondrial-dependent pathway, and ultimately impaired the reproduction in zebrafish.

Toxic Effects of Trazodone on Male Reproductive System via Disrupting Hypothalamic-Pituitary-Testicular Axis and Inducing Testicular Oxidative Stress

Depression and anxiety are recognized as public health problems. Epidemiological studies have shown that depression and anxiety often occur during reproductive ages between 20 and 60 years of age in males. Trazodone is one of the most frequently prescribed drugs in the treatment of depression and anxiety. Drugs used in repeated doses also play a role in the etiology of infertility. In our study, it was aimed to identify the possible toxic effects of trazodone on male rats and elucidate the underlying mechanisms. Vehicle or trazodone (5, 10, and 20 mg/kg/day) was administered to rats for 28 consecutive days (n = 8 per group). At the end of that period, sperm concentration, motility, morphology, and DNA damage were determined and testicular morphology was assessed histopathologically in rats. Additionally, we investigated hormonal status by determining serum testosterone, FSH, and LH levels and oxidative stress by determining glutathione and malondialdehyde levels in testicular tissue to elucidate mechanisms of possible reproductive toxicity. According to our results, sperm concentration, sperm motility, and normal sperm morphology were decreased; sperm DNA damage was increased in trazodone-administered groups. Degenerative findings on the testicular structure were observed after trazodone administration in rats. Additionally, serum FSH, LH, and testosterone levels were elevated in the trazodone-administered groups. Increased MDA levels were the signs of enhanced oxidative stress after trazodone administration in testis tissues. Thus, we concluded that trazodone induced reproductive toxicity in male rats; this reproductive toxicity was accompanied by oxidative stress and hormonal changes, which are considered as important causes of reproductive disorders.

Sertraline-induced reproductive toxicity in male rats: evaluation of possible underlying mechanisms

This study was conducted to clarify the toxic effects of sertraline (SRT) on the reproductive system of male rats and to elucidate the underlying mechanisms. Rats were treated orally with SRT at doses of 5, 10, and 20 mg kg-1 for 28 consecutive days. At the end of the treatment period, sperm concentration, sperm motility, and sperm morphology were investigated by computer-assisted sperm analysis system whereas sperm DNA damage was detected by comet assay. The oxidative status of the testes was investigated, and a histopathological examination was conducted. Serum testosterone, follicle-stimulating hormone (FSH), and luteinizing hormone (LH) levels were measured to determine the effects of SRT on the spermatogenesis process. One-way ANOVA, post-hoc Dunnett's T3 test for the sperm comet assay, and post-hoc Tukey's test for the others were performed for statistical analysis. The results showed that SRT caused an increase in sperm DNA damage and induced histopathological lesions in all groups treated with SRT. There was abnormal sperm morphology and increased malondialdehyde (MDA) in the 10 mg kg-1 treatment group. More dramatic changes were observed in the 20 mg kg-1 treatment group. Decreased sperm count was accompanied by a significant increase in abnormal sperm morphology, DNA damage, and degeneration in cellular-tubular structures. Serum LH and testosterone levels were elevated in the 20 mg kg-1 treatment group. Decreased glutathione (GSH) and increased MDA were signs of enhanced oxidative stress (OS). In conclusion, SRT induced testicular toxicity in a dose-dependent manner and OS is suggested as a crucial mechanism.

Comparative effects of zinc oxide, zinc oxide nanoparticle and zinc-methionine on hatchability and reproductive variables in male Japanese quail

The objective was to examine the effect of different dietary zinc sources on reproduction of male Japanese quail. A total of 512 quail chicks (day-old) were divided into four groups with four replications for a period of 42 days. After this period, excess chicks were removed to attain the ratio of one male to three females and 16 quail in each subgroup. At 52 to 60 d of age, the eggs were collected and incubated. The basal diet (control) contained no zinc and the other three experimental diets were supplemented with 25 and 50 mg/kg zinc from zinc oxide (ZnO), zinc oxide nanoparticles (ZnONP) and zinc-methionine (Zn-Met) for 1 to 35 and 36 to 60 days, respectively. On day 42, two males from each replicate were euthanized. Males from the ZnO and Zn-Met treatments had an increase (P < 0.05) in seminiferous tubule diameters (STD) and germinal epithelium thickness (GET) compared with the control and ZnONP treatments. Cloacal gland index (CGI) was greatest (P < 0.05) for the Zn-Met compared with the other groups. Testosterone concentration was greater (P < 0.05) in the ZnO and Zn-Met compared with the other groups. Addition of Zn-Met to the diet enhanced (P < 0.05) fertility, hatchability and hatched chick weight compared with the other groups. Early and late embryonic death was greater (P < 0.05) in the control and ZnONP groups, respectively, compared with the other groups. This study indicated that supplementing diets with the Zn-Met source improves male Japanese quail reproductive performance and hatchability traits while zinc oxide nanoparticles have detrimental effects on male Japanese quail reproduction and reduces hatchability.

Insulin-like 3 expression and fibrosis induction after intra-testicular injection of magnetic nanoparticles in rat testis and the ameliorative role of Echinacea purpurea extract

The World Health Organization has approved magnetic nanoparticles (MNP) for use as a contrast agent for magnetic resonance imaging or tumor hyperthermia treatment. MNP are toxic over time after intra-testicular injection. A clear strategy to ameliorate the toxic side effects of MNP in normal tissues after medical application has not yet been developed. We used an extract of Echinacea purpurea (EP) as a natural source of antioxidant and free radical scavenging product for detoxification of MNP in testicular tissues. MNP localization in the interstitial area of testicular tissue reduced the expression of insulin-like factor 3 (INSL3) proteins as well as serum testosterone levels. Further, MNP caused accumulation of both collagen and elastin in the interstitial area and increased the thickness of the tunica albuginea. Injection of MNP during administration of EP extract for short periods slightly reduced the toxic side effects of MNP. After extended exposure to EP extract, INSL3 expression and testosterone returned to near control levels. Also, collagen and elastin accumulation caused by MNP was reduced after extended exposure to EP extract. We believe that the ameliorative effect of EP extract is due to its antioxidant properties.

Simultaneous size characterization and mass quantification of the in vivo core-biocorona structure and dissolved species of silver nanoparticles

Size characterization of silver nanoparticles with biomolecule corona (AgNP@BCs) and mass quantification of various silver species in organisms are essential for understanding the in vivo transformation of AgNPs. Herein, we report a versatile method that allows simultaneous determination of the size of AgNP@BCs and mass concentration of various silver species in rat liver. Both particulate and ionic silver were extracted in their original forms from the organs by alkaline digestion, and analyzed by size exclusion chromatography combined with inductively coupled plasma mass spectrometry (SEC-ICP-MS). While the silver mass concentrations were quantified by ICP-MS with a detection limit of 0.1μg/g, the effective diameter of AgNP@BCs was determined based on the retention time in SEC separation with size discrimination of 0.6-3.3nm. More importantly, we found that the BC thickness of AgNP@BCs is core size independent, and a linear correlation was found between the effective diameter and core diameter of AgNP@BCs in extracted tissues, which was used to calibrate the core diameter with standard deviations in the range of 0.2-1.1nm. The utility of this strategy was demonstrated through application to rat livers in vivo. Our method is powerful for investigating the transformation mechanism of AgNPs in vivo.

Biogenic synthesis of copper oxide nanoparticles using olea europaea leaf extract and evaluation of their toxicity activities: An in vivo and in vitro study

Copper oxide nanoparticles (CUNPs) were synthesized using Olea europaea leaf extract as reducing and protecting agent. The formation of nanoparticles was observed through a color change from yellowish to brownish black. The CUNPs were confirmed with UV-Vis spectrophotometer, which revealed a peak absorbance at 289 nm. The synthesized CUNPs were characterized by XRD, FTIR, SEM, and TEM. The XRD pattern revealed that CUNPs were crystalline in nature with a diameter around 20 nm. FTIR spectral analysis showed that CUNPs were capped with plant constituents. From SEM and TEM analyses, the CUNPs were generally found to be spherical in shape, and the size range was 20-50 nm. Free radical scavenging potential of CUNPs against DPPH was confirmed by its stable antioxidant effects. In addition, the toxicity of CUNPs in mice was also assessed by body weight and weights of liver, kidneys, spleen, and thymus. The immune response in mice was signaled through an obvious change in spleen and thymus index, with a decrease of ADA enzyme activity in serum, spleen, and thymus after CUNPs treatment. The CUNPs were found to exert cell growth arrest against AMJ-13 and SKOV-3 cancer cells in a dose-dependent manner and induce cell death by apoptosis. Less significant cytotoxic effect was observed in normal dermal fibroblast cells. These findings suggest that CUNPs may have the potential to be anticancer agents. © 2017 American Institute of Chemical Engineers Biotechnol. Prog., 34:218-230, 2018.

In vitro exposure of bull sperm cells to DMSA-coated maghemite nanoparticles does not affect cell functionality or structure

Magnetic nanoparticles can be used in different areas of biology. It is therefore important to know the effects of such nanomaterials on germline cells as they may traverse the blood-testis barrier. This work aimed to evaluate the response of bull sperm after exposure to a magnetic fluid containing DMSA-coated maghemite nanoparticles (MNP-DMSA) in order to determine nanotoxicity. Bull sperm was incubated with MNP-DMSA at final concentrations of 0.06, 0.03 or 0.015 mg Fe/mL. Sperm kinetics, plasma membrane integrity and acrosome reaction were evaluated over a 4 h incubation period. The sperm cells were also evaluated by transmission electron microscopy. Exposure of bull sperm to MNP-DMSA did not affect sperm kinetics or integrity. Neither ultrastructural damage of sperm cells nor uptake of nanoparticles by the spermatozoa was observed. In conclusion, MNP-DMSA does not affect sperm function or structure under the conditions tested.

A re-assessment of the safety of silver in household water treatment: rapid systematic review of mammalian in vivo genotoxicity studies

BACKGROUND

Despite poor evidence of their effectiveness, colloidal silver and silver nanoparticles are increasingly being promoted for treating potentially contaminated drinking water in low income countries. Recently, however, concerns have been raised about the possible genotoxicity of particulate silver.

OBJECTIVES

The goal of this paper was to review the published mammalian in vivo genotoxicity studies using silver micro and nanoparticles.

METHODS

SCOPUS and Medline were searched using the following search string: ("DNA damage" OR genotox* OR Cytotox* OR Embryotox*) AND (silver OR AgNP). Included papers were any mammalian in vivo experimental studies investigating genotoxicity of silver particles. Studies were quality assessed using the ToxRTool.

RESULTS

16 relevant papers were identified. There were substantial variations in study design including the size of silver particles, animal species, target organs, silver dose, route of administration and the method used to detect genotoxicity. Thus, it was not possible to produce a definitive pooled result. Nevertheless, most studies showed evidence of genotoxicity unless using very low doses. We also identified one human study reporting evidence of "severe DNA damage" in silver jewellery workers occupationally exposed to silver particles.

CONCLUSIONS

With the available evidence it is not possible to be definitive about risks to human health from oral exposure to silver particulates. However, the balance of evidence suggests that there should be concerns especially when considering the evidence from jewellery workers. There is an urgent need to determine whether people exposed to particulate silver as part of drinking water treatment have evidence of DNA damage.

Reproductive toxicity after levetiracetam administration in male rats: Evidence for role of hormonal status and oxidative stress

Levetiracetam (LEV) is an antiepileptic drug commonly used in the treatment of epilepsy because of its excellent safety profile in all age groups. It is remarkable that there are no studies evaluating the toxic effects of this drug on the male reproductive system, as it is commonly used in male patients of reproductive age. From this point of view, our aim was to evaluate the possible toxic effects of LEV on the male reproductive system. Therefore, LEV was administered to male rats orally at 50, 150, and 300 mg/kg for 70 consecutive days. At the end of this period, alterations to body and organ weights were calculated, and sperm concentration, motility, and morphology were investigated by a computer-assisted sperm analysis system. Sperm DNA damage was determined by comet assay and histopathological examination of the testes was carried out. Serum testosterone, follicle-stimulating hormone (FSH), and luteinizing hormone (LH) levels were measured by ELISAs to determine the effects of hormonal status, while glutathione, superoxide dismutase, catalase, and malondialdehyde levels in the testes were measured by colorimetric assay kits to determine the role of oxidative status in potential toxicity. According to the results, sperm quality was decreased by LEV treatment in a dose-dependent manner. LEV induced significant DNA damage in the 150 and 300 mg/kg LEV-administered groups. Histopathology of the testes showed that LEV resulted in testicular injury in the 300 mg/kg LEV-administered group. Serum testosterone, FSH, and LH levels were significantly decreased in the 300 mg/kg LEV-administered group. Glutathione, superoxide dismutase, and catalase levels were significantly decreased in all experimental groups while malondialdehyde levels were significantly increased in 150 and 300 mg/kg LEV-administered groups. According to these results, it was determined that LEV administration decreased sperm quality and it was alleged that hormonal alteration and oxidative stress are potential contributors to reproductive toxicity.

Citalopram Induces Reproductive Toxicity in Male Rats

BACKGROUND

Citalopram hydrobromide (CTL) has been shown to cause sexual dysfunction; however, its reproductive toxicity potential has not been sufficiently elucidated in men. Therefore, we aimed to clarify the toxic effects of CTL on the reproductive system of male rats.

METHODS

For this purpose, CTL was administered at 5, 10, and 20 mg/kg/day to rats orally for 28 days. Sperm concentration, motility, and morphology were investigated using a computer-assisted sperm analysis system, and sperm DNA damage was detected using a Comet assay. The testes were histopathologically examined. Serum follicle-stimulating hormone, luteinizing hormone, and testosterone levels were measured and the oxidative status of testes was investigated.

RESULTS

Our results showed that sperm concentration was reduced, and abnormal sperm morphology and sperm DNA damage were increased in CTL-administered groups. Additionally, histopathological changes were observed in the testes of CTL-administered rats. Luteinizing hormone levels were increased in CTL-administered groups, while testosterone levels were increased in the 5 and 10 mg/kg CTL-administered groups. Decreased glutathione signaled enhanced oxidative stress in the 10 and 20 mg/kg CTL-administered groups.

CONCLUSION

Thus, we concluded that CT induced testicular damage in male rats; this testicular damage was accompanied by oxidative stress and hormonal changes, which are considered as the important causes of reproductive disorders. Birth Defects Research 109:475-485, 2017. © 2017 Wiley Periodicals, Inc.

Nano-safety Research: Examining the Associations among the Biological Effects of Nanoparticles and Their Physicochemical Properties and Kinetics

In the past decade, nanotechnology has advanced rapidly, and many products containing nanoparticles are now an important part of our daily lives. Despite our increasing exposure to nanoparticles, however, information regarding the absorption, distribution, metabolism, excretion, and toxicity of nanoparticles remains limited. In this review, we introduce our group's ongoing research into the biological effects and toxicities of nanoparticles, which we broadly refer to as "nano-safety research." In addition to determining the biological effects of nanoparticles and elucidating the underlying mechanisms of those effects, we are also exploring the associations among the physicochemical properties and kinetics of nanoparticles. Furthermore, we are currently developing a battery of biomarkers that we hope will be used to predict the biological effects of nanoparticles during the early stages of development. Our research provides valuable basic information on the safety of nanoparticles. We hope that this information will be used for the development of better assessments of nanoparticles safety and for the creation of more appropriate regulations to ensure not only the safety but also the sustainability of nanotechnology.

A review of reproductive and developmental toxicity of silver nanoparticles in laboratory animals

We summarized significant effects reported in the literature on the reproductive and developmental toxicity of silver nanoparticles (AgNPs) in laboratory animals. AgNPs showed testicular/sperm toxicity in males and ovarian and embryonic toxicity in females. Maternal injection of AgNPs delayed physical development and impaired cognitive behavior in offspring. Ag was accumulated in the testes after administration of AgNPs. AgNPs were identified in the visceral yolk sac after administration during early gestation in mice. Radiolabeled AgNPs were detected in placenta, breast milk, and pre- and postnatal offspring after injection during late gestation in rats. Ag in the ionic form, and possibly also particles, was suggested to be bioavailable. Although this review provides initial information on the potential reproductive and developmental toxicity of AgNPs, data is still very limited. Further studies using state-of-the-art methodologies and the relevant routes and doses for human exposure are required.

Pulmonary exposure to cellulose nanocrystals caused deleterious effects to reproductive system in male mice

Over the past several years there has been an increased number of applications of cellulosic materials in many sectors, including the food industry, cosmetics, and pharmaceuticals. However, to date, there are few studies investigating the potential adverse effects of cellulose nanocrystals (CNC). The objective of this study was to determine long-term outcomes on the male reproductive system of mice upon repeated pharyngeal aspiration exposure to CNC. To achieve this, cauda epididymal sperm samples were analyzed for sperm concentration, motility, morphological abnormalities, and DNA damage. Testicular and epididymal oxidative damage was evaluated, as well as histopathology examination of testes. In addition, changes in levels of testosterone in testes and serum and of luteinizing hormone (LH) in serum were determined. Three months after the last administration, CNC exposure significantly altered sperm concentration, motility, cell morphology, and sperm DNA integrity. These parameters correlated with elevated proinflammatory cytokines levels and myeloperoxidase (MPO) activity in testes, as well as oxidative stress in both testes and epididymis. Exposure to CNC also produced damage to testicular structure, as evidenced by presence of interstitial edema, frequent dystrophic seminiferous tubules with arrested spermatogenesis and degenerating spermatocytes, and imbalance in levels of testosterone and LH. Taken together, these results demonstrate that pulmonary exposure to CNC induces sustained adverse effects in spermatocytes/spermatozoa, suggesting male reproductive toxicity.

Intravenous administration of silver nanoparticles causes organ toxicity through intracellular ROS-related loss of inter-endothelial junction

Background

Administration of silver nanoparticles (AgNPs) to mice could result in their distribution and accumulation in multiple organs, with notable prominence in liver, lungs, and kidneys. However, how AgNPs transport through blood vesicular system to reach the target organs is unclear, and the precise differences in the mechanisms of toxicity between AgNPs and silver ions still remain elusive. In the present research, the pathological changes on these target organs with a focus on inter-endothelial junction was investigated to gain a new insight of AgNPs toxicity by comparing the mechanisms of action of AgNPs and AgNO₃.

Methods

We investigated the in vitro cytotoxicity of either citrated-coated AgNPs (10, 75, and 110 nm) or silver nitrate (AgNO₃) following 24 h incubations (1–40 μg/mL) in the presence of primary human umbilical vein endothelial cells (HUVEC). Meanwhile, we detected the effects of AgNPs on intercellular conjunction and intracellular ROS by VE-cadherin staining and 2′, 7′-dichlorodihydrofluorescein diacetate (DCFH-DA) assay, respectively. To assess in vivo toxicity, we administered single or multiple intravenous injections (25 μg Ag for AgNPs and 2.5 μg Ag for AgNO₃ per dose) to mice.

Results

In the in vitro study, the TEM observation showed that AgNPs were taken up by endothelial cells while AgNO₃ was taken up little. Meanwhile AgNPs incubation induced the elevation of intracellular ROS and down-regulation of VE-cadherin between the endothelial cells and affected the cytoskeleton actin reorganization, which could be rescued by antioxidant N-acetylcysteine. In contrast, AgNO₃ caused direct cell death when the concentration was higher than 20 μg/mL and without ROS induction at lower concentration. The release of AgNPs from leaking vessels induced peripheral inflammation in the liver, lungs, and kidneys, and the severity increased in proportion to the diameter of the AgNPs used.

Conclusion

It is AgNPs but not AgNO₃ that were taken up by vascular endothelial cells and induced intracellular ROS elevated, which was closely related to disruption of the integrity of endothelial layer. The AgNPs-induced leakiness of endothelial cells could mediate the common peripheral inflammation in liver, kidney and lung through intravenous exposure.

Electronic supplementary material

The online version of this article (doi:10.1186/s12989-016-0133-9) contains supplementary material, which is available to authorized users.

Evaluation of in vivo graphene oxide toxicity for Acheta domesticus in relation to nanomaterial purity and time passed from the exposure

Graphene and its oxidized form-graphene oxide (GO) have become exceptionally popular in industry and medicine due to their unique properties. However, there are suspicions that GO can cause adverse effects. Therefore, comprehensive knowledge on its potential toxicity is essential. This research assesses the in vivo toxicity of pure and manganese ion contaminated GO, which were injected into the hemolymph of Acheta domesticus. The activity of catalase (CAT) and gluthiathione peroxidases (GSTPx) as well as heat shock protein (HSP 70) and total antioxidant capacity (TAC) levels were measured at consecutive time points-1h, 24h, 48h and 72h after injection. Neither pure GO nor GO contaminated with manganese were neutral to the organism. The results proved the intensification of oxidative stress after GO injection, which was confirmed by increased enzyme activity. The organism seems to cope with this stress, especially in the first 24h after injection. In the following days, increasing HSP 70 levels were observed, which might suggest the synthesis of new proteins and the removal of old and damaged ones. With that in mind, the potential toxicity of the studied material, which could lead to serious and permanent damage to the organism, should still be taken into consideration.

Testicular biodistribution of silica-gold nanoparticles after intramuscular injection in mice

With the continuing development of nanomaterials, the assessment of their potential impact on human health, and especially human reproductive toxicity, is a major issue. The testicular biodistribution of nanoparticles remains poorly studied. This study investigated whether gold-silica nanoparticles could be detected in mouse testes after intramuscular injection, with a particular focus on their ability to cross the blood-testis barrier. To that purpose, well-characterized 70-nm gold core-silica shell nanoparticles were used to ensure sensitive detection using high-resolution techniques. Testes were collected at different time points corresponding to spermatogenesis stages in mice. Transmission electron microscopy and confocal microscopy were used for nanoparticle detection, and nanoparticle quantification was performed by atomic emission spectroscopy. All these techniques showed that no particles were able to reach the testes. Results accorded with the normal histological appearance of testes even at 45 days post sacrifice. High-resolution techniques did not detect 70-nm silica-gold nanoparticles in mouse testes after intramuscular injection. These results are reassuring about the safety of nanoparticles with regard to male human reproduction, especially in the context of nanomedicine.

Effects of oral exposure to silver nanoparticles on the sperm of rats

It has been demonstrated that exposure to silver nanoparticles (AgNPs) can induce toxicological effects in rodents. In this study, we investigated whether sub-chronic oral exposure to different doses of polyvinil pyrrolidone (PVP)-coated AgNPs (PVP-AgNPs) (50, 100 and 200mg/kg/day) could induce harmful effects on epididymal sperm rat parameters. Sperm motility, viability and morphology were examined. Moreover, a histological evaluation of testis and epididymis was also performed. High doses of PVP-AgNPs showed higher sperm morphology abnormalities, while a progressive, but not significant effect, was observed in other sperm parameters. The current results suggest that oral sub-chronic exposure to PVP-AgNPs induces slight toxicological effects in sperm rat parameters.

Silver nanoparticles disrupt germline stem cell maintenance in the Drosophila testis

Silver nanoparticles (AgNPs), one of the most popular nanomaterials, are commonly used in consumer products and biomedical devices, despite their potential toxicity. Recently, AgNP exposure was reported to be associated with male reproductive toxicity in mammalian models. However, there is still a limited understanding of the effects of AgNPs on spermatogenesis. The fruit fly Drosophila testis is an excellent in vivo model to elucidate the mechanisms underlying AgNP-induced defects in spermatogenesis, as germ lineages can be easily identified and imaged. In this study, we evaluated AgNP-mediated toxicity on spermatogenesis by feeding Drosophila with AgNPs at various concentrations. We first observed a dose-dependent uptake of AgNPs in vivo. Concomitantly, AgNP exposure caused a significant decrease in the viability and delay in the development of Drosophila in a dose-dependent manner. Furthermore, AgNP-treated male flies showed a reduction in fecundity, and the resulting testes contained a decreased number of germline stem cells (GSCs) compared to controls. Interestingly, testes exposed to AgNPs exhibited a dramatic increase in reactive oxygen species levels and showed precocious GSC differentiation. Taken together, our study suggests that AgNP exposure may increase ROS levels in the Drosophila testis, leading to a reduction of GSC number by promoting premature GSC differentiation.

Effects of silver nanoparticles on neonatal testis development in mice

Background

Metal nanoparticles (MNPs) play an important role in consumer products. An increasing use of MNPs has raised concerns about potential risks for human health. Therefore, in vivo tests of MNPs are urgently required. Using mice as a model animal, the aim of the present study was designed to investigate the effect of biologically synthesized silver nanoparticles (AgNPs) on spermatogenesis in neonatal mice.

Methods

AgNPs were synthesized using Bacillus funiculus. The prepared nanoparticles were characterized using various analytical techniques such as UV–visible spectroscopy, X-ray diffraction, Fourier transform-infrared spectroscopy, and transmission electron microscopy. The prepared AgNPs were used to investigate testis development in neonatal mice. Institute of Cancer Research neonatal male mice were used in all experiments and were treated with different doses (0, 1, and 5 mg/kg) of AgNPs five times (interval of 3 days from postnatal day [PND] 8–21) by abdominal subcutaneous injection.

Results

The results showed that the sperm abnormalities such as quality and quantity were significantly increased by the synthesized AgNPs. The diameter of the convoluted tubules shrank significantly in mice treated with AgNPs on PND28 and PND42. The results of reverse transcription-quantitative polymerase chain reaction indicated that the E1f1ay, Gsta4, and Fdx1 genes were up-regulated, and the Amh, Cx43, and Claudin-11 genes were down-regulated in response to AgNPs exposure on PND28; however, these genes recovered at PND60. AgNPs had no effect on the recombination levels of chromosomes in germ cells.

Conclusion

These results demonstrated the adverse effects of AgNPs on the male reproductive tract, particularly spermatogenesis and the quality of sperm. This study suggests that the development of nanomaterials should be safer and non-toxic to the living organisms and the potential reprotoxicity of AgNPs should be investigated more carefully.

Applications of the comet assay in particle toxicology: air pollution and engineered nanomaterials exposure

Exposure to ambient air particles is associated with elevated levels of DNA strand breaks (SBs) and endonuclease III, formamidopyrimidine DNA glycosylase (FPG) and oxoguanine DNA glycosylase-sensitive sites in cell cultures, animals and humans. In both animals and cell cultures, increases in SB and in oxidatively damaged DNA are seen after exposure to a range of engineered nanomaterials (ENMs), including carbon black, carbon nanotubes, fullerene C60, ZnO, silver and gold. Exposure to TiO2 has generated mixed data with regard to SB and oxidatively damaged DNA in cell cultures. Nanosilica does not seem to be associated with generation of FPG-sensitive sites in cell cultures, while large differences in SB generation between studies have been noted. Single-dose airway exposure to nanosized carbon black and multi-walled carbon nanotubes in animal models seems to be associated with elevated DNA damage levels in lung tissue in comparison to similar exposure to TiO2 and fullerene C60. Oral exposure has been associated with augmented DNA damage levels in cells of internal organs, although the doses have been typically very high. Intraveneous and intraperitoneal injection of ENMs have shown contradictory results dependent on the type of ENM and dose in each set of experiments. In conclusion, the exposure to both combustion-derived particles and ENMs is associated with increased levels of DNA damage in the comet assay. Particle size, composition and crystal structure of ENM are considered important determinants of toxicity, whereas their combined contributions to genotoxicity in the comet assay are yet to be thoroughly investigated.

Genotoxicity and gene expression modulation of silver and titanium dioxide nanoparticles in mice

Recently, we showed that silver nanoparticles (AgNPs) caused apoptosis, necrosis and DNA strand breaks in different cell models in vitro. These findings warranted analyses of their relevance in vivo. We investigated the genotoxic potential and gene expression profiles of silver particles of nano- (Ag20, 20 nm) and submicron- (Ag200, 200 nm) size and titanium dioxide nanoparticles (TiO2-NPs, 21 nm) in selected tissues from exposed male mice including the gonades. A single dose of 5 mg/kg bw nanoparticles was administered intravenously to male mice derived from C57BL6 (WT) and 8-oxoguanine DNA glycosylase knock-out (Ogg1(-/-) KO). Testis, lung and liver were harvested one and seven days post-exposure and analyzed for DNA strand breaks and oxidized purines employing the Comet assay with Formamidopyrimidine DNA glycosylase (Fpg) treatment, and sperm DNA fragmentation by the sperm chromatin structure assay (SCSA). Based on an initial screening of a panel of 21 genes, seven genes were selected and their expression levels were analyzed in all lung and testis tissues sampled from all animals (n = 6 mice/treatment group) using qPCR. AgNPs, in particular Ag200, caused significantly increased levels of DNA strand breaks and alkali labile sites in lung, seven days post-exposure. Fpg-sensitive lesions were significantly induced in both testis and lung. The transcript level of some key genes; Atm, Rad51, Sod1, Fos and Mmp3, were significantly induced compared to controls, particularly in lung samples from Ag200-exposed KO mice. We conclude that the Ag200 causes genotoxicity and distinct gene expression patterns in selected DNA damage response and repair related genes.

Perturbation of cellular mechanistic system by silver nanoparticle toxicity: Cytotoxic, genotoxic and epigenetic potentials

Currently the applications of silver nanoparticles (Ag NPs) are gaining overwhelming response due to the advancement of nanotechnology. However, only limited information is available with regard to their toxicity mechanism in different species. It is very essential to understand the complete molecular mechanism to explore the functional and long term applications of Ag NPs. Ag NPs could be toxic at cellular, subcellular, biomolecular, and epigenetic levels. Toxicity effects induced by Ag NPs have been evaluated using numerous in vitro and in vivo models, but still there are contradictions in interpretations due to disparity in methodology, test endpoints and several other model parameters which needs to be considered. Thus, this review article focuses on the progressive elucidation of molecular mechanism of toxicity induced by Ag NPs in various in vitro and in vivo models. Apart from these, this review also highlights the various ignored factors which are to be considered during toxicity studies.

Internalization of silver nanoparticles into mouse spermatozoa results in poor fertilization and compromised embryo development

Silver nanoparticles (AgNPs) have many features that make them attractive as medical devices, especially in therapeutic agents and drug delivery systems. Here we have introduced AgNPs into mouse spermatozoa and then determined the cytotoxic effects of AgNPs on sperm function and subsequent embryo development. Scanning electron microscopy and transmission electron microscopy analyses showed that AgNPs could be internalized into sperm cells. Furthermore, exposure to AgNPs inhibited sperm viability and the acrosome reaction in a dose-dependent manner, whereas sperm mitochondrial copy numbers, morphological abnormalities, and mortality due to reactive oxygen species were significantly increased. Likewise, sperm abnormalities due to AgNPs internalization significantly decreased the rate of oocyte fertilization and blastocyst formation. Blastocysts obtained from AgNPs-treated spermatozoa showed lower expression of trophectoderm-associated and pluripotent marker genes. Overall, we propose that AgNPs internalization into spermatozoa may alter sperm physiology, leading to poor fertilization and embryonic development. Such AgNPs-induced reprotoxicity may be a valuable tool as models for testing the safety and applicability of medical devices using AgNPs.

Toxicogenomic responses of human liver HepG2 cells to silver nanoparticles

The increased use of silver nanoparticles (AgNPs) in foods and cosmetics has raised public safety concerns. However, only limited knowledge exists on the effect of AgNPs on the cellular transcriptome. This study evaluated global gene expression profiles of human liver HepG2 cells exposed to 20 and 50 nm AgNPs for 4 and 24 h at 2.5 µg ml(-1) . Exposure to 20 nm AgNPs resulted in 811 altered genes after 4 h, but much less after 24 h. Exposure to 50 nm AgNPs showed minimal altered genes at both exposure times. The HepG2 cells responded to the toxic insult of AgNPs by transiently upregulating stress response genes such as metallothioneins and heat shock proteins. Functional analysis of the altered genes showed more than 20 major biological processes were affected, of which metabolism, development, cell differentiation and cell death were the most dominant categories. Several cellular pathways were also impacted by AgNP exposure, including the p53 signaling pathway and the NRF2-mediated oxidative stress response pathway, which may lead to increased oxidative stress and DNA damage in the cell and potentially result in genotoxicity and carcinogenicity. Together, these results indicate that HepG2 cells underwent a multitude of cellular processes in response to the toxic insult of AgNP exposure, and suggest that toxicogenomic characterization of human HepG2 cells could serve as an alternative model for assessing toxicities of NPs.

Influence of gold, silver and gold-silver alloy nanoparticles on germ cell function and embryo development

The use of engineered nanoparticles has risen exponentially over the last decade. Applications are manifold and include utilisation in industrial goods as well as medical and consumer products. Gold and silver nanoparticles play an important role in the current increase of nanoparticle usage. However, our understanding concerning possible side effects of this increased exposure to particles, which are frequently in the same size regime as medium sized biomolecules and accessorily possess highly active surfaces, is still incomplete. That particularly applies to reproductive aspects, were defects can be passed onto following generations. This review gives a brief overview of the most recent findings concerning reprotoxicological effects. The here presented data elucidate how composition, size and surface modification of nanoparticles influence viablility and functionality of reproduction relevant cells derived from various animal models. While in vitro cultured embryos displayed no toxic effects after the microinjection of gold and silver nanoparticles, sperm fertility parameters deteriorated after co-incubation with ligand free gold nanoparticles. However, the effect could be alleviated by bio-coating the nanoparticles, which even applies to silver and silver-rich alloy nanoparticles. The most sensitive test system appeared to be in vitro oocyte maturation showing a dose-dependent response towards protein (BSA) coated gold-silver alloy and silver nanoparticles leading up to complete arrest of maturation. Recent biodistribution studies confirmed that nanoparticles gain access to the ovaries and also penetrate the blood-testis and placental barrier. Thus, the design of nanoparticles with increased biosafety is highly relevant for biomedical applications.

In vivo toxicity of orally administrated silicon dioxide nanoparticles in healthy adult mice

The increasing use of silica nanoparticles (SiNPs) in various applications including industrial, agriculture, and medicine has raised concerns about their potential risks to human health. Various nanotoxicity researches have been done on the assessment of SiNPs' toxic effects; however, a few in vivo investigations exist. In this investigation, an in vivo study was done in order to evaluate the oral toxicity of SiNPs. The biochemical levels of 19 different serum parameters were assessed. Moreover, the histopathological changes have been examined as well. We showed that SiNPs with diameters of 10-15 nm in size can cause significant changes in albumin, cholesterol, triglyceride, total protein, urea, HDL, and LDL as well as in alkaline phosphatase and aspartate aminotransferase activity. In addition, histopathological examinations demonstrated that SiNPs have toxic effects on various tissues including liver, kidney, lung, and testis.

Histopathological and ultra structural effects of nanoparticles on rat testis following 90 days (Chronic study) of repeated oral administration

Background

Nanoparticles (Ag NPs) have recently received much attention for their possible applications in biotechnology and biomedical. However, little is known about the toxicity in reproductive organs of animal model following exposure to nanoparticles.

Objective

This study therefore, tried to examine the effects of nanoparticles with a diameter range of 5-20 nm on the histology of the testis of wistar rats and correlate it with Transmission Electron Microscopy results.

Materials and methods

Sixteen wistar rats were randomly divided into two groups of 8 rats each. Each group received the following via gavage technique for 90 days: Control Group (Group-1)-tap water; Experimental group (Group 2) - nanoparticles (20ug/kg/day). After ninety days (chronic study), rats were sacrificed and testis tissues was processed for histology and transmission electron microscopic study.

Results

There was significant difference between the observations of group-1 and group 2. The changes observed in the testis were disarray of the spermatogenic cells and disorientation of the testis. These changes were observed to have been disappearing from normal histological features. Detailed structural damages were observed with TEM analysis, such as depletion of germ cells, germinal cells necrosis, especially in spermatogonia and Leydig cells had an abnormal fibroblast-like appearance, abnormal space between neighboring sertoli cells, mitochondria, lost cristae and vacuolated (none energized) with those animals exposed to nanoparticles.

Conclusion

It seems that nanoparticles have acute and significant effects on spermatogenesis and number of spermatogenic cells. More experimental investigations are necessary to elucidate better conclusion regarding the safety of nanoparticles on male reproduction system.

Engineered nanomaterials: an emerging class of novel endocrine disruptors

Over the past decade, engineered nanomaterials (ENMs) have garnered great attention for their potentially beneficial applications in medicine, industry, and consumer products due to their advantageous physicochemical properties and inherent size. However, studies have shown that these sophisticated molecules can initiate toxicity at the subcellular, cellular, and/or tissue/organ level in diverse experimental models. Investigators have also demonstrated that, upon exposure to ENMs, the physicochemical properties that are exploited for public benefit may mediate adverse endocrine-disrupting effects on several endpoints of mammalian reproductive physiology (e.g., steroidogenesis, spermatogenesis, pregnancy). Elucidating these complex interactions within reproductive cells and tissues will significantly advance our understanding of ENMs as an emerging class of novel endocrine disruptors and reproductive toxicants. Herein we reviewed the recent developments in reproductive nanotoxicology and identified the gaps in our knowledge that may serve as future research directions to foster continued advancement in this evolving field of study.

Sub-acute intravenous administration of silver nanoparticles in male mice alters Leydig cell function and testosterone levels

The aim of this study was to determine whether short-term, in vivo exposure to silver nanoparticles (AgNPs) could be toxic to male reproduction. Low dose (1mg/kg/dose) AgNPs were intravenously injected into male CD1 mice over 12 days. Treatment resulted in no changes in body and testis weights, sperm concentration and motility, fertility indices, or follicle-stimulating hormone and luteinizing hormone serum concentrations; however, serum and intratesticular testosterone concentrations were significantly increased 15 days after initial treatment. Histologic evaluation revealed significant changes in epithelium morphology, germ cell apoptosis, and Leydig cell size. Additionally, gene expression analysis revealed Cyp11a1 and Hsd3b1 mRNA significantly upregulated in treated animals. These data suggest that AgNPs do not impair spermatogonial stem cells in vivo since treatment did not result in significant decreases in testis weight and sperm concentrations. However, AgNPs appear to affect Leydig cell function, yielding increasing testicular and serum testosterone levels.

Long-term effects of silver nanoparticles on reproductive activity of rabbit buck

Using the rabbit as an animal model, this study evaluated the long-term effect of silver nanoparticles (NPs) administered intravenously (0.6 mg/kg bw) on reproductive activity and sperm quality. Semen analysis was performed by optical microscopy and sperm motility evaluation by computer assisted sperm analyzer (CASA). Mitochondria oxygen consumption, light and transmission electron microscopy of rabbit testis and ejaculated sperm were also carried out. Throughout the experiment NP-treated rabbits showed higher seminal reactive oxygen species (ROS), less motile sperm, and lower curvilinear velocity and oxygen consumption than control animals. In contrast, libido, serum testosterone, sperm concentration, and semen volume were hardly affected by NPs. Transmission electron microscopy analysis did not show any evident morphological damage in testes; however, Ag NPs are visible in spermatids and ejaculated sperm. These preliminary results show that Ag NPs can reach the testes, compromising sperm motility, sperm speed, and acrosome and mitochondria shape and function.