Perfluorooctane sulfonate and perfluorooctanoic acid induce plasma membrane dysfunction in boar spermatozoa during in vitro capacitation.

Spermatozoa require the capacitation, a series of biochemical events, to perform fertilization. Many toxic compounds can interfere in this process, including perfluorooctane sulfonate (PFOS) and perfluorooctanoic acid (PFOA), which belong to the perfluoroalkyl substances (PFAS). Since both substances are found in many everyday materials and are highly persistent, they accumulate in organisms where they have been associated with fertility problems. This study analyzes the effects of PFOS and PFOA on the functionality of boar spermatozoa, and changes in the plasma membrane (PM) during capacitation. The median lethal concentrations (LC50) of PFOS and PFOA were 460 and 1894 µM, respectively, while the mean inhibitory concentrations of capacitation (ICC50) were 274 µM and 1458 µM, respectively. The ICC50 of PFOA was insufficient to reduce the capacitation, but 950 µM (½ LC50) of PFOA and the ICC50 of PFOS significantly reduced the number of capacitated spermatozoa. PFOS and PFOA also impeded the progesterone (P4)-induced acrosomal reaction (iAR). These effects occur despite the accumulation of [Ca2+]i under capacitating conditions. The accumulation of [Ca2+]i produces saturation, which prevents its entry through ionophore A23187 and P4 in the presence of PFOS. Membrane potential (Emv) was deregulated. Both PFAS affected lipid membrane conductance mediated by valinomycin. The spermatozoa presented 49% and 47% of membrane dysfunction with PFOS and PFOA, respectively. By causing membrane damage, both substances prevented the release of cholesterol and altered the organization of membrane microdomains (MMDs). Data indicate that both PFAS caused alterations in PM functionality.

Perfluorooctane Sulfonate (PFOS) and Perfluorohexane Sulfonate (PFHxS) Alters Protein Phosphorylation, Increase ROS Levels and DNA Fragmentation during In Vitro Capacitation of Boar Spermatozoa.

Perfluorooctane sulfonate (PFOS) and perfluorohexane sulfonate (PFHxS) are toxic and bioaccumulative, included in the Stockholm Convention's list as persistent organic pollutants. Due to their toxicity, worldwide distribution, and lack of information in spermatozoa physiology during pre-fertilization processes, the present study seeks to analyze the toxic effects and possible alterations caused by the presence of these compounds in boar sperm during the in vitro capacitation. The spermatozoa capacitation was performed in supplemented TALP-Hepes media and mean lethal concentration values of 460.55 µM for PFOS, and 1930.60 µM for PFHxS were obtained. Results by chlortetracycline staining showed that intracellular Ca2+ patterns bound to membrane proteins were scarcely affected by PFOS. The spontaneous acrosome reaction determined by FITC-PNA was significantly reduced by PFOS and slightly increased by PFHxS. Both toxic compounds significantly alter the normal capacitation process from 30 min of exposure. An increase in ROS production was observed by flow cytometry and considerable DNA fragmentation by the comet assay. The immunocytochemistry showed a decrease of tyrosine phosphorylation in proteins of the equatorial and acrosomal zone of the spermatozoa head. In conclusion, PFOS and PFHxS have toxic effects on the sperm, causing mortality and altering vital parameters for proper sperm capacitation.