Investigation of the effects of sub-chronic polyethylene terephthalate nanoplastic exposure on testes and sperm in mice

Infertility, which is defined as the inability to achieve pregnancy after 12 months or more of regular unprotected sexual intercourse, is a disease arising from the male or female reproductive organs. Many genetic and lifestyle factors are thought to be associated with male infertility. It has been reported that exposure to micro and nanoplastics, which is among these lifestyle factors, may also be effective in infertility. In this study, we aimed to investigate the effect of one of the synthetic polymers, polyethylene terephthalate (PET) nanoplastics, on male reproductive health. For this aim, eighteen five-week-old Balb-C type mice were randomly selected and divided into three groups as control group, low-dose PET-NP and high-dose PET-NP administration group (n=6). 100 µL of saline was given to the control group, 0.1 mg/day PET nanoplastic to the low dose group, and 0.5 mg/day PET nanoplastic to the high dose group for 28 days, by oral gavage. Our data revealed that sub-chronic PET nanoplastics exposure did not result in a significant change in testes index compared to the control group (P<0.05), while there was significant decrease in sperm counts in both low and high dose groups compared to that of control group (Pz0.05). Similarly, sperm morphologies of both low and high dose PET-NP exposed animals were significantly changed, while the percentages of sperms with normal morphology significantly decreased compared to that of untreated control (P<0.05). Furthermore, there was a significant increase in sperm neck anomalies in the group exposed to high-dose PET nanoplastics compared to the that of control 10 group (P<0.01). Also, there was a significant increase in the sperm % tail DNA of the groups exposed to PET nanoplastics, which were revealed by COMET analysis, indicating the DNA damage (P<0.05). Lastly, Tubule structures of histological sections taken from testicles were evaluated by Johnsen scoring and a significant change in spermatogenesis was observed in both groups exposed to PET nanoplastic compared to that of control group (P<0.05). In conclusion, sub-chronic PET nanoplastics exposure led to decrease in sperm count, disruption in sperm morphology, induces DNA strand breaks and have a negative impact in the stages of spermatogenesis. As a result of these negative effects, PET nanoplastic negatively affects male reproductive health.