Effect of the potential endocrine disruptor BEH-TEBP on mitochondrial function and oxidative stress during in vitro maturation of porcine oocytes.

Endocrine disruptors represent a diverse group of substances that negatively affect the reproductive health of mammals. Bis(2-ethylhexyl)-2,3,4,5-tetrabromophthalate (BEH-TEBP) is a brominated flame retardant used as a replacement for polybrominated diphenyl ethers, yet its potential effects on reproductive health remain insufficiently investigated. The aim of this thesis was to analyze the effects of the potential endocrine disruptor BEH- TEBP on mitochondrial function, redox balance, and meiotic maturation of porcine oocytes during in vitro maturation. The results demonstrated that BEH-TEBP reduces the ability of oocytes to complete maturation to the metaphase II (MII) stage. At the highest concentration of 100 µM, the maturation rate decreased to 48.97% compared to 91.48% in the control group. Changes were also observed in mitochondrial distribution and the formation of functional clusters typical of competent oocytes. Oocytes exposed to 100 µM BEH-TEBP exhibited predominantly homogeneous mitochondrial distribution as well as changes in the expression of FIS1 and MFN1, suggesting a shift toward increased mitochondrial fission. BEH-TEBP also affected redox balance. At 10 µM, an increase in reactive oxygen species (ROS) production was observed together with an upregulation of SOD2 expression,...