Impact of glyphosate and its formulation Roundup® on stallion spermatozoa

The growing and widespread use of glyphosate-based herbicides (GBHs) has raised an intense public debate about the impact of environmental contamination on animal and human health, including male fertility. The aim of this study was to deepen the impact of glyphosate (Gly) and GBHs on mammalian sperm investigating the effect of in vitro exposure of stallion spermatozoa to Gly and to its commercial formulation Roundup (R) (R). Spermatozoa were incubated at 37 degrees C with different Gly or R concentrations (from 0.5 to 720 mg/mL Gly or R at the same Gly-equivalent concentrations). After 1 h of incubation motility, viability, acrosome integrity, mitochondrial activity and ROS production were assessed. Gly, at all the concentrations tested, did not induce any detrimental impact on the sperm quality parameters evaluated. Conversely, R starting from 360 mg/mL (Gly-equivalent dose) significantly (P < 0.05) decreased total and progressive motility, viability, acrosome integrity, mitochondrial activity and the percentage of live spermatozoa with intact mitochondria not producing ROS. Our results indicate that the commercial formulation R is more toxic than its active molecule Gly and that the negative impact on stallion sperm motility might be likely due to a detrimental effect mainly at membrane and mitochondrial level and, at least in part, to redox unbalance. Moreover, based on the data obtained, it can be hypothesized a species-specificity in sperm sensitivity to Gly and GBHs as horse spermatozoa were negatively influenced at higher concentrations of R compared to those reported in literature to be toxic for human and swine male germ cells. (C) 2021 Elsevier Inc. All rights reserved.

Automated summary

This study investigated the impact of glyphosate and glyphosate-based herbicides on stallion sperm. The results indicate that the commercial formulation Roundup has a more toxic effect on sperm motility and viability compared to the active molecule glyphosate. The negative impact is likely due to damage to the sperm membrane and mitochondria, as well as redox imbalance. Interestingly, horse sperm appear to be more sensitive to higher concentrations of Roundup compared to other species such as humans and pigs.