Numerous factors affect reproduction, including stress, diet, obesity, the use of stimulants, or exposure to toxins, along with heavy elements (lead, silver, cadmium, uranium, vanadium, mercury, arsenic). Metals, like other xenotoxins, can cause infertility through, e.g., impairment of endocrine function and gametogenesis or excess production of reactive oxygen species (ROS). The advancement of nanotechnology has created another hazard to human safety through exposure to metals in the form of nanomaterials (NMs). Nanoparticles (NPs) exhibit a specific ability to penetrate cell membranes and biological barriers in the human body. These ultra-fine particles (<100 nm) can enter the human body through the respiratory tract, food, skin, injection, or implantation. Once absorbed, NPs are transported to various organs through the blood or lymph. Absorbed NPs, thanks to ultrahigh reactivity compared to bulk materials in microscale size, disrupt the homeostasis of the body as a result of interaction with biological molecules such as DNA, lipids, and proteins; interfering with the functioning of cells, organs, and physiological systems; and leading to severe pathological dysfunctions. Over the past decades, much research has been performed on the reproductive effects of essential trace elements. The research hypothesis that disturbances in the metabolism of trace elements are one of the many causes of infertility has been unquestionably confirmed. This review examines the complex reproductive risks for men regarding the exposure to potentially harmless xenobiotics based on a series of 298 articles over the past 30 years. The research was conducted using PubMed, Web of Science, and Scopus databases searching for papers devoted to in vivo and in vitro studies related to the influence of essential elements (iron, selenium, manganese, cobalt, zinc, copper, and molybdenum) and widely used metallic NPs on male reproduction potential.

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An Overview of Essential Microelements and Common Metallic Nanoparticles and Their Effects on Male Fertility

Various studies have shown that the reproductive organs are highly sensitive to toxic elements found in the environment. Due to technological progress, the use of nanoparticles has become more common nowadays. Nanoparticles are used for drug delivery because their dimensions allow them to circulate throughout the body and enter directly into the cell. Antimicrobial properties are increasingly used in the manufacture of medical devices, textiles, food packaging, cosmetics, and other consumer products. Nanoparticles provide several benefits, but aspects related to their effects on living organisms and the environment are not well known. This review summarizes current in vivo, and in vitro animal studies focused on the evaluation of toxicity of selected metal nanoparticles (Ag, ZnO, TiO2) on male and female reproductive health. It can be concluded that higher concentrations of metal nanoparticles in the male reproductive system can cause a decrease in spermatozoa motility, viability and disruption of membrane integrity. Histopathological changes of the testicular epithelium, infiltration of inflammatory cells in the epididymis, and prostatic hyperplasia have been observed. Nanoparticles in the female reproductive system caused their accumulation in the ovaries and uterus. Metal nanoparticles most likely induce polycystic ovary syndrome and follicular atresia, inflammation, apoptosis, and necrosis also occurred.

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Effects of Selected Metal Nanoparticles (Ag, ZnO, TiO2) on the Structure and Function of Reproductive Organs

Investigation of Trace Elements in Vegan Foods by ICP-MS After Microwave Digestion

The aim of this study was to determine the effect of semen extender supplementation with 25 or 50 μM of zinc nanoparticles (ZnNPs) or manganese nanoparticles (MnNPs) on turkey spermatozoa preserved in a liquid state. Twenty turkey ejaculates were obtained from twenty healthy males. The collected semen was preserved at 4 °C for 48 h with or without NPs. Selected qualitative and quantitative parameters of sperm (motility, plasma membrane activity, mitochondrial membrane potential (MMP) and the percentage of sperm demonstrating NO and SOD activity) were examined after 2, 24 and 48 h of storage. Sperm motility and MMP decreased in semen preserved with ZnNPs at each time point of the analysis. However, all spermatozoa remained viable throughout storage. In contrast, membrane integrity and mitochondria activity (p ≤ 0.05) increased, and the highest SOD activity (p ≤ 0.05) was observed in semen preserved with MnNPs. The addition of MnNPs to the semen extender could potentially improve the parameters of turkey semen during prolonged storage.

Influence of Zinc and Manganese Nanoparticles on Selected Parameters of Turkey Spermatozoa Stored in a Liquid State at 4 °C.

INTRODUCTION
Zinc oxide nanoparticles (ZnO-NPs) are known for their antioxidant effects. In this study, ZnO-NPs were synthesized using aqueous extract of Maclura pomifera fruit; then, their effects on the quality of ram cauda epididymal spermatozoa were evaluated during storage at 4 ºC.


METHODS
ZnO-NPs formation was characterized by ultraviolet-visible spectroscopy (Uv-vis), energy dispersive spectroscopy (EDX), field emission scanning electron microscopes (FE-SEM), and Fourier transform infrared (FTIR) spectroscopy. Cytotoxicity responses were investigated by 3-[4,5-dimethylthiazole-2-yl]-2,5- diphenyltetrazolium bromide (MTT). Cauda epididymal spermatozoa were obtained from testicles collected from abattoir(s). The sperm samples were pooled. The samples were diluted by extender and supplemented with different concentrations of ZnO-NPs (0, 1, 5, and 25 µg/mL) and cooled to 4ºC for 72 h. Total motility, viability, DNA and membrane integrity, morphological abnormality, malondialdehyde (MDA) and antioxidant activities: superoxide dismutase (SOD) and total antioxidant capacity (TAC) of cooled diluted samples were evaluated.


RESULTS
Addition of 1μg/mL of ZnO-NPs increased sperm viability under normal conditions (P<0.05). Extender supplementation with 1μg/mL of ZnO-NPs improved sperm total motility, viability, DNA and membrane integrity during storage periods (P<0.05). Moreover, using 1μg/mL of ZnO-NPs improved (P<0.05) MDA, TAC and SOD activities after 72h compared to other treatments.


CONCLUSIONS
In conclusion, there were some beneficial effects of ZnO-NPs supplementation in ram epididymal sperm extender during oxidative stress conditions and cooled storage.

Klaudia Bułka

Papers

The effect of ZnO nanoparticles on rabbit spermatozoa motility and viability parameters in vitro