Mechanism of deoxynivalenol-induced neurotoxicity in weaned piglets is linked to lipid peroxidation, dampened neurotransmitter levels, and interference with calcium signaling.

Deoxynivalenol（DON） has broad toxicity in livestock, but we know little about its neurotoxic mechanisms. We investigated DON neurotoxicity in the cerebral cortex, cerebellum, and hippocampus of "Duroc × Landrace × Yokshire" piglets. Control piglets were fed a basal diet, while those in low- and high-treatment groups were fed diets with 1.3 mg/kg and 2.2 mg/kg DON, respectively. After a 60 d trial, scanning electron microscopy revealed the destruction of hippocampal cell ultrastructure. As DON concentrations increased, oxidative damage also increased in the cerebral cortex, cerebellum, and hippocampus. Norepinephrine and 5-hydroxytryptamine concentrations tended to increase, whereas dopamine and γ-aminobutyric acid concentrations decreased. We also observed an increase in calcium concentration, relative mRNA expression of calcium/calmodulin-dependent protein kinase II (CaMKII), and CaMKII phosphorylation. However, calmodulin (CaM) mRNA and protein content decreased. Overall, our results suggest that DON acts through the Ca2+/CaM/CaMKII signaling pathway to influence cerebral lipid peroxidation and neurotransmitter levels.

Deoxynivalenol Induces Intestinal Damage and Inflammatory Response through the Nuclear Factor-κB Signaling Pathway in Piglets.

Deoxynivalenol (DON) is highly toxic to animals and humans, but pigs are most sensitive to it. The porcine mucosal injury related mechanism of DON is not yet fully clarified. Here, we investigated DON-induced injury in the intestinal tissues of piglet. Thirty weanling piglets [(Duroc × Landrace) × Yorkshire] were randomly divided into three groups according to single factor experimental design (10 piglets each group). Piglets were fed a basal diet in the control group, while low and high dose groups were fed a DON diet (1300 and 2200 µg/kg, respectively) for 60 days. Scanning electron microscopy results indicated that the ultrastructure of intestinal epithelial cells in the DON-treated group was damaged. The distribution and optical density (OD) values of zonula occludens 1 (ZO-1) protein in the intestinal tissues of DON-treated groups were decreased. At higher DON dosage, interleukin (IL)-1ß, IL-6, and tumor necrosis factor-α mRNA levels were elevated in the intestinal tissues. The mRNA and protein levels of NF-κB p65, IκB-α, IKKα/ß, iNOS, and COX-2 in the small intestinal mucosa were abnormally altered with an increase in DON concentration. These results indicate that DON can persuade intestinal damage and inflammatory responses in piglets via the nuclear factor-κB signaling pathway.

Deoxynivalenol induces toxicity and apoptosis in piglet hippocampal nerve cells via the MAPK signaling pathway.

Deoxynivalenol (DON) is a mycotoxin capable of producing a variety of toxic effects in human and animals. In this study, the effect of DON treatment on cytotoxicity and apoptotic pathways in piglet hippocampal nerve cells (PHNCs) was determined. The effects of DON on cellular morphology, cell activity, lactate dehydrogenase (LDH) release, the protein expression of mitogen-activated protein kinase (MAPK) pathway, and the relative expression of key genes related to apoptosis were evaluated. The results indicated that DON significantly inhibited cellular viability and promoted the release of LDH by damaging the membrane integrity of PHNCs, however, the cellular viability was increased and LDH leakage rate were decreased after adding MAPK inhibitors. DON induced PHNCs apoptosis and phosphorylation of MAPK pathway proteins dose-dependently. The ratios of phospho p-JNK/JNK and p-p38/p38 significantly increased with the increase of DON concentration, while the p-ERK/ERK ratio significantly decreased. In addition, DON upregulated the BAX mRNA level, and downregulated the BCL2 mRNA level. Pre-incubation with inhibitors of JNK (SP600125) and p38 (SB202190) significantly decreases the BAX/BCL2 ratio. However, pre-incubation with the inhibitor of ERK (U0126), significantly increased the BAX/BCL2 ratio. These data demonstrated that DON induces toxic effects and apoptosis in PHNCs via the MAPK signaling pathway.

Effects of deoxynivalenol exposure on cerebral lipid peroxidation, neurotransmitter and calcium homeostasis of chicks in vivo.

During current research, the effects of deoxynivalenol (DON) exposure on cerebral lipid peroxidation, neurotransmitter secretion and calcium homeostasis in chicks were evaluated. One hundred and twenty Hailan chicks (male, 1-day-old) were randomly divided into four groups. Chicks in low, medium and high dose groups were fed with 0.27, 1.68 and 12.21 mg/kg-1 DON respectively by gavage according to feed intake. Chicks in control group were fed with physiological saline by gavage. The trials were conducted for 36 d. At the end of the trials, twenty chicks per group were sacrificed, and the cerebra were collected for measuring the brain indices. Compared with the control group, the activities of total superoxide dismutase (T-SOD) and glutathione peroxidase were significantly decreased in treatment groups (P < 0.05), the contents of malondialdehyde in high dose group were increased (P < 0.05), the catalase activities and nitric oxide contents in medium and high dose groups were decreased (P < 0.05), and the activities of T-AOC in high dose group were reduced (P < 0.05). Compared with the control group, the concentrations of norepinephrine and 5-hydroxytryptamine in high dose group were obviously increased (P < 0.05), while the concentrations of dopamine were decreased (P < 0.05). Meanwhile, the concentrations of calcium and calmodulin (CaM) in medium and high dose groups were lower than those of the control group (P < 0.05), and the gene relative expression of CaM mRNA in treatment groups were significantly reduced (P < 0.05), in a dose-dependent manner. These results suggested that DON exposure can affect the cerebral lipid peroxidation, neurotransmitters secretion and the balance of calcium homeostasis in chicks.

Deoxynivalenol induces apoptosis in PC12 cells via the mitochondrial pathway.

Deoxynivalenol (DON) has broad toxicity in animals and humans. In this study the impact of DON treatment on apoptotic pathways in PC12 cells was determined. The effects of DON were evaluated on (i) typical indicators of apoptosis, including cellular morphology, cell activity, lactate dehydrogenase (LDH) release, and apoptosis ratio in PC12 cells, and on (ii) the expression of key genes and proteins related to apoptosis, including Bcl-2, Bax, Bid, cytochrome C (Cyt C), apoptosis inducing factor (AIF), cleaved-Caspase9, and cleaved-Caspase3. DON treatment inhibited proliferation of PC12 cells, induced significant morphological changes and apoptosis, promoted the release of Cyt C and AIF from the mitochondria, and increased the activities of cleaved-Caspase9 and cleaved-Caspase3. Bcl-2 expression decreased with increasing DON concentrations, in contrast to Bax and Bid, which were increased with increasing DON concentration. These data demonstrate that DON induces apoptosis in PC12 cells through the mitochondrial apoptosis pathway.