Tetraconazole interrupts mitochondrial function and intracellular calcium levels leading to apoptosis of bovine mammary epithelial cells

Tetraconazole is a type of fungicide that eliminates pathogens in plants and fruit. To date, studies have focused on the direct exposure of plants and fruits to residual tetraconazole, but no studies have been conducted on the indirect effects of tetraconzaole. Given the importance of cows as milk-producing animals and their potential exposure to pesticides via plant consumption, we analyzed the mechanism by which tetraconazole influences milk production. Here, we confirmed that tetraconazole-induced apoptosis and inhibited cell viability and proliferation by regulating the cell cycle in bovine mammary epithelial cells (MAC-T). In addition, Ca²⁺ homeostasis in mitochondria was disrupted by tetraconazole, leading to the depolarization of mitochondrial membrane potential. Consistent with the proliferation-related findings, tetraconazole downregulated AKT, ERK1/2, P38, and JNK signaling pathways and proliferation-related proteins such as CCND1 and PCNA in MAC-T cells. Meanwhile, it upregulated cleaved caspase 3, BAX, and Cytochrome c under the same conditions in MAC-T cells. Furthermore, MAC-T exposed to tetraconazole causes a failure of proper autophagy functioning. In summary, the results of this study indicated that tetraconazole exposure may lead to a failure of milk production from bovine mammary epithelial cells by disrupting calcium homeostasis and mitochondrial function.