Reproductive organs are essential not only for the life of an individual but also for the survival and development of the species. The response of reproductive organs to toxic substances differs from that of other target organs, and they may serve as an ideal “barometer” for the deleterious effects of environmental pollution on animal and human health. The incidence of infertility, cancers, and associated maladies has increased in the last fifty years or more, while various anthropogenic activities have released into the environment numerous toxic substances, including cadmium, lead, and mercury. Data from epidemiological studies suggested that environmental exposure to cadmium, lead, and mercury may have produced reproductive and developmental toxicity. The present review focused on experimental studies using rats, mice, avian, and rabbits to demonstrate unambiguously effects of cadmium, lead, or mercury on the structure and function of reproductive organs. In addition, relevant human studies are discussed. The experimental studies reviewed have indicated that the testis and ovary are particularly sensitive to cadmium, lead, and mercury because these organs are distinguished by an intense cellular activity, where vital processes of spermatogenesis, oogenesis, and folliculogenesis occur. In ovaries, manifestation of toxicity induced by cadmium, lead, or mercury included decreased follicular growth, occurrence of follicular atresia, degeneration of the corpus luteum, and alterations in cycle. In testes, toxic effects following exposure to cadmium, lead, or mercury included alterations of seminiferous tubules, testicular stroma, and decrease of spermatozoa count, motility and viability, and aberrant spermatozoa morphology.

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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Verbascoside, the main component of Lippia citriodora extract, is one of the most powerful free radical scavengers exhibiting a wide biological activity. In in vivo study 20 adult New Zealand white rabbit bucks were divided into two homogeneous groups, one control (CON) and one verbascoside-supplemented (0.1%) in feed mixture (EXP) and later in vitro effects of verbascoside on the motility aspects of rabbit spermatozoa were analysed. The spermatozoa concentration, ejaculate volume, spermatozoa motility, progressive motility, distance parameters, velocity parameters and type of spermatozoa movement were negatively affected by Lippia citriodora leaves extract after the first 4 weeks of dietary treatment, till the end of experiment (8 weeks). Four weeks after the suspension of feed additive supplementation, all spermatozoa traits values returned to the normality, and in line with CON group. For in vitro findings, ejaculates from 10 male New Zealand white bucks were collected using an artificial vagina. Then it was diluted in physiological saline solution containing different concentrations of verbascoside at the concentration of 0, 0.0024, 0.0219, 0.157, 120.0 mg/ml (Ctrl, VB1, VB2, VB3, VB4 groups, respectively), using a dilution ratio of 1 : 4. The obtained data proved that verbascoside at the concentration of 0.0024 and 0.0219 mg/ml had no adverse effect on spermatozoa. Additionally, we found that verbascoside at higher concentrations (0.157 and 120.0 mg/ml) significantly altered all the motility parameters analysed in the experiment. In conclusion a possible negative effect of verbascoside supplementation into feed mixture (0.1%) on semen quality parameters in rabbit bucks as well as in vitro can be stated, obviously considering that target organs of antioxidant activities of phenylpropanoid glycosides are various. In addition it has to be emphasized that the extract showed a reversible action, since the semen traits of treated animals returned to the normality after the dietary administration period.

Zinc plays a very important role in various biological activities of the body. Multifaceted role of zinc is also known in testes development, spermatogenesis, capacitation and has effect on spermatozoa motility. On the other hand, the growing industry of nanotechnology has created reasonable interest of the risk assessment for nanoparticles. The aim of this study was to evaluate in vitro effect of zinc oxide (ZnO) nanoparticles on rabbit spermatozoa. Fresh semen was collected from sexually mature New Zealand rabbits. Experimental groups were prepared by diluting semen with ZnO nanoparticles in seven different concentrations (6–391 mg/mL). The experimental groups were compared with control group. Semen was assessed using computer assisted semen analysis (CASA) at intervals of 0, 1, 2 and 3 h of incubation. The mitochondrial toxicity assay (MTT) assay was used to determine cell viability. The results of monitored motility parameters in experimental groups showed a decreasing trend during whole experiment. Significant decrease (P < 0.001) of motility and progressive motility was observed after 3 h of incubation in samples cultured with higher ZnO nanoparticles in comparison to the control group. After 3 h of incubation, viability of rabbit spermatozoa showed slightly increased values in group with the lowest concentration of ZnO nanoparticles, but in other groups viability showed non-significant decrease compared to control. Similar tendency was detected for spermatozoa membrane integrity. These original data show the negative dose–dependent effect of ZnO nanoparticles on spermatozoa motility and viability parameters.