ABSTRACT
Deoxynivalenol (DON) is a toxic secondary metabolite produced by Fusarium graminearum. It is one of the most common feed contaminants that poses a serious threat to the health and performance of dairy cows. This study investigated the in vitro cytotoxicity of DON on bovine mammary epithelial cells (MAC-T). DON at different concentrations (0.25, 0.3, 0.5, 0.8, 1 or 2 µg/ml) inhibited the growth of MAC-T cells after 24 hr of exposure (p < .001). DON at 0.25 µg/ml increased lactate dehydrogenase (LDH) leakage (p < .05); decreased glutathione (GSH) levels (p < .001), total superoxide dismutase (T-SOD) activity and total antioxidant capacity (T-AOC; p < .01); and increased malondialdehyde (MDA) concentration (p < .01) in MAC-T cells after 24 hr of exposure. We also observed that DON increased reactive oxygen species (ROS) levels in cells incubated for 9, 15 and 24 hr (p < .001). DON at 0.25 µg/ml triggered oxidative damage in MAC-T cells. Furthermore, it induced an inflammatory response in the cells incubated for 9, 15 and 24 hr (p < .05) by increasing the mRNA expression levels of nuclear factor kappa B, myeloid differentiation factor 88 (MyD88), tumour necrosis factor-α (TNF-α), interleukin-1ß (IL-1ß), IL-6, cyclooxygenase-2 and IL-8. We further examined the effect of DON on apoptosis. DON prevented normal proliferation of MAC-T cells by blocked cell cycle progression in 24 hr (p < .001). In addition, the apoptosis rate measured using annexin V-FITC significantly increased (p < .05) with increase in the mRNA expression level of Bax (p < .01) and increase in the Bax/Bcl-2 ratio (p < .01) in cells incubated for 24 hr. In summary, DON exerts toxic effects in MAC-T cells by causing oxidative stress, inducing an inflammatory response, affecting cell cycle and leading to apoptosis.
