Lead does not succumb to biological decomposition, and its ability to accumulate in the body makes it a serious threat to the health of people and animals, while affecting the reproductive function. In most cases, poisoning with lead remains asymptomatic. In a number of studies the authors concluded that in men the level of lead in the blood more than >40 μg/dL leads to the disorder of reproductive functions, such as low libido, a small sperm volume, the amount of spermatozoa, an increase in the abnormal morphology of spermatozoa and decrease in their motility. Male factors are considered the main cause of infertility in 40% of infertile couples and contribute to the emergence of this state in combination with female factors in 20% of cases. The mechanisms of how lead causes male infertility are covered in depth. It is assumed that the basic effect on the reproductive function of men is likely to occur due to changes in the reproductive hormonal axis and hormonal control of spermatogenesis, and not due to direct toxic effects on the seminiferous tubules. The adverse effect of lead on the male reproductive function, especially at low doses (<10 μg/dl), has not been studied properly yet. The risk of lead poisoning is directly connected not only with an increase in concentration, but also with the duration of the impact of metal. There are a number of possible ways of how exposure of lead reduces male fertility. Lead, most likely, impairs the endocrine profile of regulation, mainly through the axis of the hypothalamus-pituitary testosterone, hereafter reduces the production of sperm in the seminiferous tubules of the testicles. At the same time, it acts as an endocrine destroyer, affecting hormones responsible for the production of sperm. In addition to changes in the reproductive hormone axis and hormonal control of spermatogenesis, the activity of enzymes, such as alkaline phosphatase and potassium-sodium ATP-ase, direct toxic effects on the seminiferous tubules, the exposure time of the metal and its dose affect male infertility. Another problem associated with the reproductive toxicity of lead is determined by the excessive generation of the reactive oxygen species. It is known that the oxidative stress caused by lead is involved in the abnormal functions of spermatozoa and male infertility. The possibility to decrease lead level in the body using a number of methods, such as chelatotherapy, nano-encapsulation, use of N-acetylcysteine is considered. Conclusion. Based on animal studies, it seems to be rational to prescribe the corresponding antioxidants to persons suffering from abnormal parameters of spermatozoa and infertility due to the effects of lead. Antioxidants showed a protective effect on spermatogenesis on animal models and reduced reactive oxygen species in sperm and DNA fragmentation in studies in humans. Although there is no final evidence confirming the use of antioxidant additives in men with low fertility to improve fertility rates, it is believed that due to the low cost and a small number of side effects, antioxidants need to be recommended to men with insufficient fertility
Perspectives of Nanoparticles in Male Infertility: Evidence for Induced Abnormalities in Sperm Production
