JBRA Assisted Reproduction 2025;29(Suppl.2 SBRA 2025):4
Oral Presentation
29^th Annual Congress of the SBRA. São Paulo/SP - Brazil, 2025
doi: 10.5935/1518-0557.20263518

O-04. Cyhalofop-butyl Exposure During Gametogenesis: Embryotoxicity and Histopathological Findings in a Murine Model

Ana Carolina Nogueira Martinhago¹, Carlos Vaz², Maria Eduarda Vieira², Rafael Alonso Salvador², João Paolo Bilibio¹, Martina Cordini¹, Leticia Avi¹, Jose Roberto Santin²

¹ FertiBC Centro de Reprodução Humana - Balneário Camboriú - SC - Brasil
² Universidade do Vale do Itajaí - Itajaí - SC - Brasil

Objective: Cyhalofop-butyl (Cia-b) is a post-emergent herbicide widely used in rice farming. Although its environmental presence is well established, its effects on reproductive and systemic health in mammals remain unclear. This study aimed to evaluate the embryotoxic potential of maternal exposure to Cia-b during gametogenesis and to investigate histopathological changes in major organs in a murine model.
Methods: Sixty female B6D2F1 mice were randomly assigned to four groups (n = 15/group): a control group (Naive) and three treatment groups exposed to Cia-b via oral gavage at concentrations of 0.1 mg/L, 1.0 mg/L, or 10.0 mg/L for 19 consecutive days. After superovulation and mating, two-cell embryos were collected on Day 2 post-coitum and cultured in vitro through Day 5 to assess blastocyst formation rates. Statistical analysis included global chi-square testing and pairwise comparisons adjusted by Bonferroni, Holm-Bonferroni, and Benjamini-Hochberg false discovery rate (FDR). A subset of animals from each group underwent necropsy for histopathological analysis of brain, liver, kidneys, ovaries, and uterine tubes. The study was approved by the institutional Animal Research Ethics Committee (Protocol 009/2024).
Results: Blastocyst formation rates were 100.0% in the control group, 94.9% at 0.1 mg/L, 96.4% at 1.0 mg/L, and 94.1% at 10.0 mg/L, with no statistically significant differences between groups (p=0.124). However, histopathological analysis revealed dose-dependent systemic alterations. In the liver, centrilobular lipid accumulation was observed across all treated groups, with moderate changes at low dose and severe steatosis, megalocytosis, and vascular inflammation at higher doses. Nuclear atypia, including anisokaryosis and macronucleoli, was evident at 1.0mg/L, suggesting possible genotoxicity. Renal sections showed progression from mild tubular degeneration at 0.1 mg/L to glomerular sclerosis, cortical microhemorrhages, and diffuse tubular damage at 10.0 mg/L. In the brain, microhemorrhages and focal microgliosis were noted at 1.0 and 10.0mg/L, indicating discrete neurotoxic activation. Reproductive organs remained functionally preserved; however, all exposed groups exhibited marked vascular congestion in the ovaries and mild submucosal hemorrhage and epithelial shedding in the uterine tubes. These findings are consistent with early inflammatory or irritative responses potentially related to Cia-b exposure.
Conclusion: Although maternal exposure to Cyhalofop-butyl during gametogenesis did not significantly impair blastocyst development under the tested conditions, histopathological analysis revealed a clear dose-dependent pattern of systemic toxicity involving hepatic, renal, and neural tissues. The 1.0mg/L dose was associated with hepatocellular nuclear atypia, while the 10.0mg/L dose resulted in widespread histological alterations without further nuclear damage, suggesting a threshold between genotoxicity and multisystem toxicity. Additionally, all exposed groups presented consistent vascular congestion in the ovaries and epithelial disruption in the uterine tubes, indicating early inflammatory and vascular alterations in the female reproductive tract. These findings suggest that, even in the absence of overt embryonic loss, Cyhalofop-butyl exposure during critical windows of gametogenesis may compromise reproductive health by inducing subclinical damage to reproductive tissues. Further studies are warranted to elucidate the long-term effects on fertility and transgenerational reproductive outcomes.