Platinum nanoparticles exposure: Implications for ejaculated rabbit spermatozoa functionality

Research indicates that environmental contaminants resulting from anthropogenic activities can significantly disrupt the functional attributes of spermatozoa. The environmental burden and anthropogenic emissions of platinum nanoparticles (Pt NPs) are currently rising significantly. Small size (≤ 100 nm) and high surface area allow NPs to cross biological barriers, posing significant environmental and cellular risks. This study aimed to investigate the modulatory effects of Pt NPs on rabbit spermatozoa in vitro. Ejaculates were diluted with selected Pt NPs concentrations (1, 30, 250, and 500 µg/mL) and exposed to these concentrations for 4 h at 37 °C. Spermatozoa motility was analyzed using CASA at time intervals of 0, 2, and 4 h. Following the 4-hour exposure, mitochondrial activity, superoxide radical levels, and ProAKAP4 protein content were assessed. DNA fragmentation was examined using an immunofluorescence method to detect γH2AX, a marker of double-stranded breaks. Results of this study show that spermatozoa motility was adversely affected at all time periods, with motility declining with higher Pt NPs doses. Mitochondrial activity was significantly diminished at peak doses of Pt NPs. A similar effect was observed in the production of intracellular superoxide and the presence of γH2AX. However, this decrease was likely indicative of significant cellular lethality rather than a reduction in free radical production or DNA damage, respectively. ProAKAP4 protein levels, which serve as markers for spermatozoa motility and viability, progressively decreased with increasing Pt NPs concentrations, thereby reflecting a negative impact on spermatozoa motility and fertilization capability at the molecular level.