Fludioxonil compromises cellular homeostasis in and viability in bovine mammary epithelial cells by inducing mitochondrial dysfunction and calcium dysregulation

Fludioxonil, a fungicide commonly used in agriculture, has been detected in livestock, such as cattle, even though it is primarily intended for use in plants. Unintended exposure to fludioxonil may compromise immune cells, cardiomyocytes, and glioma cells, indicating its potential risk as an environmental hazard. However, research on the detrimental effects of fludioxonil remains scarce, particularly regarding its impact on livestock, which are directly exposed to fludioxonil because of its widespread agricultural use. In this study, we used bovine mammary epithelial (MAC-T) cells to model the effects of fludioxonil and assessed its effects on cell viability, various intracellular mechanisms, and milk production. The viability of MAC-T cells declined due to fludioxonil-induced apoptosis, as shown by a 3.8-fold increase in the number of early apoptotic cells. It also suppressed cell proliferation and induced cell cycle arrest. Furthermore, fludioxonil disrupted mitochondrial function, leading to a 2.6-fold reduction in ATP production and a 2.5-fold increase in mitochondrial membrane potential depolarization. Additionally, it caused the dysregulation of calcium ion levels in both the mitochondria and cytoplasm. Disruptions were also observed in MAPK molecules and AKT, which play critical roles in intracellular signaling. In addition, fludioxonil treatment led to elevated expression levels of inflammatory genes, followed by the downregulation of the expression of essential genes associated with milk composition. These findings indicated that fludioxonil decreased cell viability and proliferation by disrupting various intracellular mechanisms, ultimately impeding lactogenesis in bovine mammary epithelial cells.