Fipronil causes toxicity in mouse preimplantation embryos

Area of Science:

• Toxicology
• Developmental Biology
• Reproductive Toxicology

Background:

• Fipronil is a phenylpyrazole insecticide.
• FIPRON spot-on is a commercial ectoparasiticide containing fipronil.
• Preimplantation embryo development is critical for successful reproduction.

Purpose of the Study:

• To evaluate the toxicity of fipronil, FIPRON spot-on, and its secondary ingredients on mouse preimplantation embryos.
• To assess the impact on embryonic developmental capacity and quality.
• To compare in vitro and in vivo effects.

Main Methods:

• In vitro culture of mouse two-cell stage embryos with varying concentrations of fipronil and FIPRON spot-on.
• Stereomicroscopic and fluorescence staining evaluations of embryonic development and blastomere quality.
• In vivo daily oral administration of fipronil to female mice during the preimplantation period.
• Collection and examination of embryos from treated mice.

Main Results:

• Fipronil negatively affected embryonic development at 1 μM and higher concentrations in vitro.
• Reduced blastomere numbers and increased cell death were observed at higher fipronil concentrations.
• FIPRON spot-on caused massive embryo degeneration at a 10 μM fipronil equivalent concentration.
• Secondary ingredients also impaired embryo development and quality.
• In vivo administration of fipronil increased embryo cell death even at the acute reference dose.

Conclusions:

• Fipronil exhibits embryotoxicity, impairing mouse preimplantation embryo development both in vitro and in vivo.
• The commercial product FIPRON spot-on is embryotoxic, with its toxicity potentiated by secondary ingredients.
• These findings highlight potential reproductive risks associated with fipronil exposure.