Zearalenone Triggers Programmed Cell Death and Impairs Milk Fat Synthesis via the AKT-mTOR-PPARγ-ACSL4 Pathway in Bovine Mammary Epithelial Cells

Zearalenone (ZEN), a mycotoxin from Fusarium fungi, impairs fertility and milk production in female animals, however, the mechanisms remain poorly understood. Using the bovine mammary epithelial cells (MAC-T) as the model, this study investigated the impacts of ZEN on programmed cell death (PCD) and milk fat synthesis, and explored the underlying mechanism. We found that 10 ng/mL prolactin (PRL) notably enhanced the differentiation of MAC-T cells, promoting the expression of genes related to the synthesis of milk fat, protein, and lactose. Next, the toxic effects of different doses of ZEN on the differentiated MAC-T with PRL treatment were determined. 10 μM and 20 μM ZEN significantly reduced cell viability, induced oxidative stress, and triggered PCD (e.g. apoptosis and necrosis). Notably, ZEN exposure downregulated the mRNA/protein levels of critical factors involving in milk fat synthesis by disrupting the AKT-mTOR-PPARγ-ACSL4 pathway. Interestingly, melatonin (MT), known for its antioxidant properties, protected against the above ZEN-induced effects by enhancing the binding of PPARγ to the promoter regions of ACSL4, which led to the upregulated expression of ACSL4 gene. These results underscored the potential of MT to mitigate the adverse effects of ZEN on mammary cells, highlighting a way for potential therapeutic intervention.