Tetrabromobisphenol Exposure Impairs Bovine Oocyte Maturation by Inducing Mitochondrial Dysfunction

Area of Science:

• Reproductive Biology
• Environmental Toxicology
• Cell Biology

Background:

• Tetrabromobisphenol A (TBBPA) is a prevalent brominated flame retardant with known toxicity.
• Its effects on oocyte maturation remain understudied.
• Understanding TBBPA's impact is crucial for reproductive health and environmental safety.

Purpose of the Study:

• To investigate the effects of TBBPA on the maturation of bovine oocytes.
• To elucidate the underlying mechanisms of TBBPA-induced oocyte dysfunction.
• To assess the impact of TBBPA on subsequent embryonic development.

Main Methods:

• Bovine cumulus-oocyte complexes (COCs) were cultured in vitro with varying concentrations of TBBPA.
• Oocyte maturation, meiotic progression, spindle assembly, and chromosome alignment were assessed.
• Oxidative stress markers (SOD2), apoptosis (early apoptosis), and mitochondrial function (membrane potential, ATP levels, mtDNA copy number) were evaluated.
• Embryonic development and blastocyst quality were analyzed post-fertilization.

Main Results:

• TBBPA exposure impaired oocyte maturation, evidenced by disturbed polar body extrusion and reduced cumulus cell expansion.
• Defective spindle assembly and chromosome alignment were observed in TBBPA-treated oocytes.
• TBBPA induced oxidative stress and early apoptosis, mediated by SOD2 expression.
• Mitochondrial dysfunction, including decreased membrane potential, ATP levels, and mtDNA copy number (regulated by PDK3), was prominent.
• Embryonic development and blastocyst quality were significantly reduced following TBBPA exposure.

Conclusions:

• TBBPA exposure adversely affects bovine oocyte maturation and developmental competence.
• The detrimental effects are linked to TBBPA-induced oxidative stress and mitochondrial dysfunction.
• These findings highlight the potential reproductive risks associated with TBBPA contamination.